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- MARYLAND GEOLOGICAL SURVEY LOWER CRETACEOUS | |
MARYLAND peOlPOGICAL SURVEY
LOWER CRETACEOUS
BALTIMORE THE JOHNS HOPKINS PRESS
1911
| me
TBe Lord Baltimore Press
BALTIMORE, MD., U. &. A.
mMCcZ | IBRARY AUG 14 1996
HARVARD UNIVERSITY
COMMISSION
AUSTIN L. CROTHERS, : : : : 3 PRESIDENT.
GOVERNOR OF MARYLAND.
CHARLES H. STANLEY,
COMPTROLLER OF MARYLAND.
TRA REMSEN, : : 3 : x EXECUTIVE OFFICER.
PRESIDENT OF JOHNS HOPKINS UNIVERSITY.
R. W. SILVESTER, 5 Bieta : : : SECRETARY.
PRESIDENT OF MARYLAND AGRICULTURAL COLLEGE.
SCIENTIFIC STAFF
WM. BULLOCK CLARK, ‘ : : ; STATE GEOLOGIST.
SUPERINTENDENT OF THE SURVEY.
EDWARD B. MATHEWS, d . ASSISTANT STATE GEOLOGIST. CHARLES K. SWARTZ, ; : ; GEOLOGIST. EDWARD W. BERRY, : : : : : GEOLOGIST. B. L. MILLER, i : ‘ E ; : : GEOLOGIST.
A. B. BIBBINS, : : ; é E : GEOLOGIST.
LETTER OF TRANSMITTAL
To His Excellency Austin L. CroruErs,
Governor of Maryland and President of the Geological Survey Com- mission,
Sir:—I have the honor to present herewith the fourth volume of a series of reports dealing with the systematic geology and paleontology of Maryland. The preceding volumes have dealt with the Tertiary and Quaternary deposits and the remains of animal and plant life which they contain. ‘The present volume treats of the Lower Cretaceous deposits and their contained life, a knowledge of which is very important from an educational and scientific standpoint. I am,
Very respectfully, WM. BULLOCK CLARK, State Geologist.
JOHNS HOPKINS UNIVERSITY, BALTIMORE, September, 1911.
pig At
i ‘
CONTENTS
PAGE
SEERA HVA OH erste peeps ease caccken cancers sks ceilenateyetcastatia Te" ch stele ol obe whcDeuasa ahd oie: Geta su ayaneen chanson a Ly
THE LOWER CRETACEOUS DEPOSITS OF MARYLAND. By Wm.
BULLOCK CLARK, ARTHUR B. BIBBINS, AND EDWARD W. BerRRY...... 23
LEN PROD CULO Nectar retake, Ghersisle tere. sresrel ol ete aleustere ial shee de oue el etalione) oudioha sittehen eile, ates 23 THM RP EBV SLOGR AD ED Vey. vhs syeysuc endis.-sietoveso ee os arabes slaiecerel clstiole eleveehovs hess basi etene 23 TELE ECHO LO Cavemen tanetetay actlehs ta sichiche te vercre ovale seis) des, s Sah eiel Shekeveverere leveloherel olorehoase 26 CRELUCCOUSH Are Papel aero a ae deh hha ee aS ne beer te ates diate hae 28
MOwer: CTETACEOUSH s.onare citicreiess sans c ecoreloms ee wo sic terctorsyeails 28
(WippeTa CNELACCOUSS cose cicisileteia: save aaeteiehonanare crewereiercleiaic eran 29
TETViGnye an eens. (RI SOC OND O ORS CIRCE ERRORS MRR O IO ORT CAC ORTOD 30
EOC MUO eiyaetees eye vaya estas ate lous. oh ole uarlehal shee telortre: eaias ov coke her leit lod eoee 3
VET OC OTIC REM es retenaees choot Geavol ates avails shebbie ets eyeiai' Slopenene reece eintaee 3
IEINVOXOSR INE) ooo SG aicioss 6 Cela Lid ROA SEE CIRO LON role roe ns tei 32 OOK EIE KON FUT =. Bp RTE ry eh nS ERO) Cee AER ROR EE REED EE REE Se aS aE 32
EL EVISI ROY GLEN Tey Goran, o Ge Git PIER aE TE AERIS aa a creed CclIS Oe 32
TES ECEXSTONLE SS ate ISOS a CUI GH OR rR Ee EE aD BR Oe 33
PDE S EO RA GAM EC EN VALUER Vaart slave dey c) cr WMaueHn ve Go iat cfiaue wie.e she a va tehe Poco ob nine, Giersiey che else 34 IESG ICAO YEA. eA ING. Ae Sy ay os ere Reel Coepey reek oe i OREM TER RTE ioe ee I A i ce 47 STRATIGRAPHIC AND PALEONTOLOGIC CHARACTERISTICS. .......-.-++-+--- 56 TEE ROT OMIA ON GROW Pb seou at ane essai els) eile te: diiuikelled @ cite iethve, aS, oye 1giw 6! oie were esr ehele ete 57 EV CORBOMEL CHLRHORTUUELO Nave niet oid oie toa oes cic ae eae ee 58
Name andy SyNomyMiyas sc. ccm os saiveieiee ee aes cielele = 58
AT CALADISERTDULLOMN as: caic ars cee ag cle 510 3 erat yeaa nordic, aralare s 58
Mithologice Character sacs: cree Asien ee cea eee 58
Strike, Dip, and Thickness..................-..---- 60 Stratigraphic and Structural Relations............. 61
OUSAMIC MRM Sis Sie ssere ois cco eles ta ereuelis Ie lzps eo: =) Samper ees 63
LER ERATALNG CURE OTIVUGLEOM ea crs slo site es aie eetoncts @ aye) =) cates ieileaiteis) sists 64 Naimekamdl Sy mom yayin < yantec «ccc v0 - <lehel «rele si erdisielacls 64
3 Areal MOIST Uilel ONE eh is esc rerovmteierne ersle & cache crore eretens 64 it OlositEwChHaraGhens \. 58 s.cc-urste stscs «casks Suet setaue <istene Grams 64 Strike, Dip, and Thickness........................ 65 Stratigraphic and Structural Relations............. 66
Orgzamic REMAINS: wWoawscis-te lave) s accion soa osieic elawmrie oer 66
RCE GLEDS COMFOGINGLLON 9 re weenie ie ccke cies heres uclere clair erie 67
Namie rand Sy mOmy Myc. cscs scte.e o chevelere eins eles ever 67
ANVIL IDNR OU ATONY Riggs ooo dob os Boo oe GeiGdacin coc 68
itholozic Character is Hee cersns tse ele se) ste oe ees 68
Strike wbDip, sands Dhickness\. 54... s2se ce es celeeertaele © 69
; Stratigraphic and Structural Relations............. 70 Onezamic RVEMAING ris hoa vereue co cher ola ie: diel scoters eisai ate avehe 71
TOC OUMS CCELONS wa sors ew URED ire ard asl STO CaS Biba evan ae ele ener ee 72
14 CONTENTS
PAGE INTERPRETATION OF THE POTOMAC DEPOSITS..........0ceccccccccccscee 80 Surface Configuration of Crystalline Floor and Its Rela- tion to Potomac Basin of Deposition........... 86 Surface Configuration of Potomac Deposits and Its Pos- Sible ‘Interpretation: < 5.062. oe ote oe oes 87 DISTRIBUTION OF TEER ATT IAG AUNT) -EUTORAG date pecciuystenet cy che mises teee ce terse oh aren 89 "TEE GEOLOGIC: PROVINCE. 2 °2 Sie sscahc jets SRS es eee ave eee sO ee ee 96 THE LOWER CRETACEOUS FLORAS OF THE WORLD. By Epwarp WAMBERRY cc artee eter eer r ree Pe RO Cal ets Sete Se eer 99 TE NHOCOMDAN, FS PAGE sro arcusne she aiera nisi Sore ee eee eee ae ere 101 TW EBABRENETAIN | SIPA GENS ia 5 oaaca noe aie rhs OLeee Lele ae ree ate eee Sesh eae ee 127 ST ELEY CADP TEAC TA GIRS ep her Ses cane vivaetite ay eters eee ay a al SUAS Ce DS i amare eee 135 TET AUER TAG, GTAGH sa etaca cit «, ooctsue Arcade abaieneee Braces eie Hapa im omeeane na ain area 141 GENERAL) CHARACTER AND) DISTREB UDTLON|: sn cis cle sieve: cueyenn sos ohn sie are oer 146 CORRELATION OF THE POTOMAC FORMATIONS. By Epwarp W. PREERRYe "Stas ance eee ete Oe at feet © aie tera ey bs ane anes Toe ee Sev nee ERS oe Ore CTS 153 THE MUROPBAN TE FEORAS S06 24 aie.s oo siam. ol seuss. cue hte elsud era seneners eveyone cetera 159 THEL TRINITY, HRORACON DERAS. . foc fac. ce sale eee oes ee 161 THE LAKOTA FLORA OF THE BLACK HILLS.........0000-ceceecceeets 162 TM EUSON LORAS OF AEH BLACK HULES = .j5 <6 42) cere ee eee ee 162 THE LICOOTANDEM DORA Aele coat dicta dale SiS oed Tae LAER One eee 162 THM EPP Hs KN ORV LlcEs RILORAL aiea eae cto chars sinicl chore iopal serene ee eae ee 164 TEE HORS WTO WIN cLOBAS, S05, .2. 5.508 ot aioe ieucrneeensrerece evens hese eee eee 164 GENGBAT CONSIDERATIONS) 5.05.5 to e.aciieen ars ee teas Se aoe 165 THE REPTILIA OF THE ARUNDEL FORMATION. By RicHarp Swann PARAS S50 wie eheves wate ie aoe died, Sree tustes sree Sane Sele ies era teregerSTIG Re on Renae oS irs SYSTEMATIC PALEONTOLOGY, LOWER CRETACEOUS.............. 181 VERTEBRATA. RICHARD= SWANN Ui. 2.5. <esses 2s) ele sielsts eye clematis 183 MOLGUSCA. Wit~ BULLOCK (CLARK: .2..cios sowie woe aie e rae coat Dio eae 211 PTERIDOPHYTA. “EDWARD WILBER @BERRY «5 -/22)s janice ee eee eno 214 CYCADOPHYias> “HIpWARD sW.LLBER CBERRY:,,5 os. <0 stem cis ekeeieeuior ieee eltenere 313 GYAENOSPER Ma, | LD WABD:) WILBER BERRY:.(<...<))s5 10m aceite olen eee 370 MONOCOLYERDONGE. HDWABD) WEERER (BERRY. ceca. osisoeroe eee nice 452 DICOLYaMMONz. SL DWARD | WAlGRERY MRR Y 2... se © oie elisa om Seen 457 GEE NEY EVA TG IN IDRIS fave sic ore cers eye saci tes ce oceania, Sree eon ee eee a eee 597
PAT HON TOLOGIC AGS LIND BX woe soplore ele tencicnstetwelckeieke oi heberey-senevorcesyseseenetee 605
PLATE
III.
IV.
VI.
VII.
VIII.
IX.
ILLUSTRATIONS
FACING PAGE
Map showing Distribution of Potomac Deposits in Maryland...... Fig. 1—View showing basal conglomerate of the Patuxent over- lying the Piedmont Crystallines at Roland Park, Baltimore City Fig. 2.—View showing Patuxent arkosic sands and gravel in B. & O. R. R. cut at Savage, Anne Arundel County................. Fig. 1—View showing coarse, highly inclined and cross-bedded Patuxent sands near Homestead, Baltimore City.............. Fig. 2.—View showing kaolin in the Patuxent formation in cut on P. B. & W. R. R. near Perryville, Cecil County................. Fig. 1—View showing eroded upper surface of the Patuxent over- lain by Sunderland deposits, Belt Line cut near Charles Street, IBAlcinvOree Cue yiee sicts wana cletech ace coey alc iseatele a) Sr ureitans. sluie sre tduepsvetonn eiakaletets Fig. 2—View showing Patuxent-Arundel contact south shore of Spring Gardens, the probable locality where Tyson collected the historic Johns Hopkins cycad stump, Baltimore County.... Fig. 1.— View showing indurated ledges in the Patuxent formation, W Street near 12th Street, Washington, D. C................. Fig. 2.—View showing flooded iron mine in the Arundel formation near Muirkirk, Prince George’s County....................-- Fig. 1—View showing the Patuxent-Arundel contact in Belt Line cut near the eastern boundary of Baltimore City.............. Fig. 2—View showing erosion of old iron mine in the Arundel formation, Schoolhouse Hill, Baltimore County............... Fig. 1—View showing erosion of Arundel clays, Hartke Iron Mine near Hanover, Howard County................002cccceeeeces Fig. 2.—View showing Reynolds Iron Mine in the Arundel forma- tion 1 mile south of Hanover, Anne Arundel County...........
‘Near view of layers of carbonate of iron nodules in the Arundel
clays, Reynolds Iron Mine, 1 mile south of Hanover, Anne ATU CE Le © OUT Vestry se eee ees, See el roel are we Sha Ta even e san sie eRe Paaicless Fig. 1.—View showing Patapsco sands overlying Arundel clays, Cedar Hill Mine, Timberneck, 1 mile southwest of Hanover.... Fig. 2—View showing ledges of indurated sand in the Patapsco formation which is overlain by greensands of the Aquia Eocene in cut of R. F. & P. R. R. near Aquia Creek, Virginia........... Fig. 1—View showing massive variegated clay of the Patapsco formation, near Hawkins Point, Anne Arundel County........ Fig. 2.—View showing Patapsco sands and clays overlain by Pleis- tocene sands, B. & O. R. R. cut, Rosedale Hill, Baltimore County
23
32
32
40
40
60
60
80
84
84
88
88
16 ILLUSTRATIONS
PLATE FACING PAGE TSK FD EN OSA UTI oie ce ievs, Seavzye tre wc certo ase ante Pn cl eae tan ner me Oe 510-518 XEX, Dinosauria-Crocodilias : 2 ca css. he Neero ace et ete Coetetereiio ecu eeeaone be ere eee 519 EXON \ AMTO UNIS Ca ire esac soy obs Sees ero a eM OSTST EG Me Here GILG betas ic uRT eT Me Fe apie WA NTCAC eS oer 520 XOX TTX sPteridoplty tals cba es eruceaccta ein ta haere tera ears oe ae lees ea ees 521-540 RG MELVULT, — Cy cadophy:tee neat. coscs te ticsuokess woe cece eae neo siete Lone ee 541-557 DEXED XE VIELE (Gym nospertnee <5 ivecr ces selena etcvere con sseiotoe Cree Ee veinieete Grate 558-517 FEXeX EX EXO, “Monocotyledones cs ieee aac Ene eee 578, 579 DTAXOXEXIEX CVG. Dicotyledones: ess ees eee ea ee IR TRE ETE 580-596 FIGURE PAGE 1. Sketch map of the world showing the approximate location of out- crops containing Lower Cretaceous plants.................+eeee0% 150. 2. Restoration of a frond of Schizwopsis americana Berry, about four- GOH Gr) Susie oye A EDN Geel east As yore ees neem eye ict earonaat ur ta oh A eRe Aaa eA) Near a SURG 218 38. Sketch map of the world showing the Mesozoic and existing distri- butionyoL.the tannillyeVatoniaceeenace asec nese eee 234 4, Restoration of Sagenopteris elliptica, about natural size............ 288 5. Transverse section of a partly emergent but still folded frond of Cycadeoidea ingens deeply embedded. in ramentum, X 4........... 314 6. Sketch map of the world showing the approximate distribution of the CXISEINE ICV CASH Sacco stances cits ais cua eecca heme Tahal aucade NaRgie: Seton MAEM ee 315
7. Restoration of an unexpanded bisporangiate strobilus of Cycadeoidea with some of the bracts removed, about one-fourth natural size.... 317 8. A. Radial longitudinal section of an ovulate strobilus of Cycadeoidea,
somewhat -reduced: weiss we cles sos ele cee are a iete opie es oe RS locet ene 318
B. Semi-diagrammatic longitudinal section of a bisporangiate stro- bilus of Cycadeoidea, about one-half natural size.................. 318
9. Two views of the type of Williamsonia virginiensis, one-half natural SsizexGafter “Montaime diate cece meee ee he eee een eet Sao ely 10. Cuticle of Dioonites Buchianus viewed from within, X 385.......... 334
11. Cross-sections of fronds of Nilsonia densinerve. A, showing method of fossilization of specimen shown on Plate lvii, Fig. 1, natural size. B, diagrammatic cross-section of specimen shown on Plate Iviii, Fig.
Pe NATUTAT IS TAO aa, Ma hcg asa eee SN RINSE Me Rapa re Perot aioe soles ate nee aeectaecneen 363 12. Sketch map of the world showing the approximate distribution of
theviexistini: Mamacess: 25.2 sianh oo St ee it Se re cetera eee oa etn dee 376 13. View showing the whole midrib and the cuticle of one-half the lamina
ChE OG KHOLEROSOS TOCnniOwi, S< We sonccksdecanasognnanocoracs 378
14. View of a preparation of the epidermis of Frenelopsis ramosissima.. 423
15. Sketch map of the world showing the segregation of the existing Actinostrobine and the Mesozoic occurrences of Frenelopsis and Widdringtoniies liad. 0s Se ee ee BARI read aero: 427
PREFACE
The present volume is the fourth of a series of reports dealing with the systematic geology and paleontology of Maryland, the Eocene, Mio- cene, and Plio-Pleistocene deposits having already been fully described.
The Lower Cretaceous deposits which form the subject-matter of the present volume are more fully developed in the Maryland-Virginia area than anywhere else in eastern North America and the Maryland section is the type for the whole Atlantic coastal plain. Similarly the faunas and floras of the Lower Cretaceous are much more fully represented than elsewhere in this general region, the flora in particular being the richest known flora of this age.
The vertebrate fauna of the Arundel formaticn collected by Mr. John B. Hatcher and studied by the late Professor O. C. Marsh of Yale Uni- versity is of interest, since it is the only Lower Cretaceous vertebrate fauna known east of the Mississippi River, and it was upon these materials that Professor Marsh based his opinion that the Potomac was of late Jurassic age. This fauna has been thoroughly revised and elaborated in the light of additional collections by Professor R. S. Lull of the same institution. His results are in agreement with the evidence of the fossil plants, that these deposits are of Lower Cretaceous age.
The invertebrate faunas, while meagre and poorly preserved, are of great interest, since they constitute the only known representation in eastern North America of the estuarine and fluviatile invertebrate life of the Lower Cretaceous. This fauna has been described by Professor W. B. Clark of the Johns Hopkins University.
The fossil floras have been restudied by Mr. E. W. Berry of the Johns Hopkins University. The difficulties in the way of an adequate study of the Potomac flora are very great. The material, with the exception of silicified wood, lignite, and the silicified trunks of Cycadeoidea, is all
18 PREFACE
in the form of impressions, and these, while abundant and diverse, are with some notable exceptions poorly preserved as well as fragmentary, much more so than the diagrammatic figures built up from various frag- ments by previous students would lead one to suspect. The silicified wood and lignite, while abundant, has for the most part undergone so much decay before fossilization that the bulk of it is worthless. In addition to the sections made by Dr. F. H. Knowlton and forming the basis of his paper on the Fossil Wood and Lignite of the Potomac, a large number of sections have been studied by Mr. Berry, most of which proved unidentifiable, because of the extreme stage of decay before fossilization. The most perfectly preserved show only the comparatively unimportant features of the secondary wood. The petrified Cycadeoidea trunks were also found to be poorly preserved, constituting in this respect a remarkable contrast with those from the Black Hills area and elsewhere.
The necessity of some sort of systematic treatment of the maze of described forms in the literature of the Potomac which would enable the geologist or the botanist to obtain some idea of the flora has long been felt. The pre-existing multiplicity of species has made it necessary to retain a number of extremely doubtful forms. Many have, however, disappeared by reduction to synonymy, and some basis for the correlation of a number of genera with their living representatives has become apparent during the progress of the work.
Certain important forms known only from the continuation of the Maryland deposits in the Virginia area have been included, while others upon which no new light could be shed have been omitted. These latter will be discussed on a subsequent occasion in a work devoted to the Virginia area and in course of preparation for the Geological Survey of that state. Mr. Berry is indebted to various friends and colleagues both at home and abroad for assistance during the progress of the work. He is under especial obligations to the U. 8. National Museum and Dr. F. H. Knowlton for facilities in the study of the large Lower Cretaceous collections of that institution as well as for many other courtesies. The British Museum through Dr. A. Smith Woodward rendered invaluable
PREFACE 19
assistance in contributing a large number of English Wealden plants for comparison, and Professor Yokoyama of Tokio kindly forwarded Japanese material of Onychiopsis. Dr. Albert Mann of the Department of Agriculture and Doctors F. H. Blodgett and W. Ralph Jones have con- tributed photo-micrographs or camera lucida drawings.
The U. 8. Geological Survey has cooperated in furnishing a large number of the illustrations and in various other ways.
Finally any student of Lower Cretaceous floras must acknowledge his great indebtedness to previous workers who have contributed to our knowledge of these floras, more especially to Professor Seward in England, the late Marquis Saporta in Portugal, the late Professor Os- wald Heer in the Arctic regions, and Professors Ward and Fontaine in this country.
ie LOWER CRE PACEOUS: DEPOSITS OF MARYLAND
BY
WILLIAM BULLOCK CLARK
ARTHUR B. BIBBINS . AND
EDWARD W. BERRY
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE |.
SHOWING THE DISTRIBUTION OF THE
LOWER CRETACEOUS FORMATIONS
OF
MARYLAND
MARYLAND GEOLOGICAL SURVEY WM. BULLOCK CLARK, State Geotoaist
SCALE
One inch equals five miles
1: 812,600
+oo—_
1911
LEGEND
Patapseo Formation POTOMAC Arundel Formation
_ ae Patuxent Formation *
Fossil Localities MF $ £ 3 } tN we / Se) ey ew HATH pws
GROUP
i-xxul Location of Sections
y (rae .
I
WV YG allenic 14
t >, * Ne ja en NF) SASL NN o/*
JO ~ . wogdralabury YS cy.
CA ote hes ON be | “ oe ee ] Yy “yma \ (i \
Athen k Con bith Bialtinssre Mle
tine LOWER. CRETACEOUS DEPOSITS OF MARYLAND
BY
WM. BULLOCK CLARK, ARTHUR B. BIBBINS, . AND EDWARD W. BERRY
INTRODUCTION
A knowledge of the Lower Cretaceous deposits of Maryland can only be secured through an understanding of the physiography and geology of the broad province of which the State of Maryland forms a part. The physical features which characterize this area may be traced for varying distances into adjoining regions, some being recognized as far as the New England coast on the north, and others as far as the Gulf Region on the south.
THE PHYSIOGRAPHY
The region here considered forms a portion of the Atlantic slope, which stretches from the crest of the Alleghanies to the sea, and which is divided into three more or less sharply defined regions known as the Coastal Plain, the Piedmont Plateau, and the Appalachian Region. These three districts follow the Atlantic border of the United States in three belts of varying width from New England southward to the Gulf. Maryland is, therefore, closely related in its physiographic fea- tures to the States which he to the north and south of it, while its central location on the Atlantic border renders it perhaps the most char- acteristic in this broad tract. In crossing the three districts from the ocean border the country rises at first gradually, and then more rapidly, ‘until it culminates in the highlands of the western portion of the State.
24 THe Lower CrEtTAcEOUS DEpPosIts oF MARYLAND
The Coastal Plain is the name applied to the low and partially sub- merged surface of varying width extending from Cape Cod southward through Florida, and confined between the Piedmont Plateau on the west and the margin of the continental shelf on the east. The line of demarkation between the Coastal Plain and the Piedmont Plateau is sinuous and ill-defined, for the one passes over into the other oftentimes with insensible topographic gradations, although the origin of the two districts is quite different. A convenient, although somewhaé arbitrary boundary between the two regions in the Maryland area is furnished by the Baltimore and Ohio Railroad in its extension from Wilmington southwestward through Baltimore to Washington. The eastern limit of the Coastal Plain is at the edge of the continental shelf. This is located about 100 miles off shore at a depth of 100 fathoms beneath the surface of the Atlantic Ocean. It is in reality the submerged border of the North American continent, which extends seaward with a gently sloping surface to the 100-fathom line. At this point there is a rapid descent to a depth of 3000 fathoms, where the continental rise gives place to the oceanic abyss.
The Coastal Plain, therefore, falls naturally into two divisions, a sub- merged or submarine division and an emerged or subaerial dwision. The seashore is the boundary line which separates them. This line of de- markation, although apparently fixed, is in reality very changeable, for during the past geologic ages it has migrated back and forth across the Coastal Plain, at one time occupying a position well over on the Pied- mont Plateau, and at another far out at sea. At the present time there is reason to believe that the sea is encroaching on the land by the slow subsidence of the latter, but a few generations of men is too short a period in which to measure this change.
The subaérial division is itself separable in Maryland into the Hastern Shore and the Western Shore. These terms, although first introduced to designate the land masses on either side of Chesapeake Bay, are in reality expressive of a fundamental contrast in the topography of the Coastal Plain. This difference gives rise to an Hastern Shore and a Western Shore type of topography. Chesapeake Bay and Elk River sepa-
MARYLAND GRHOLOGICAL SURVEY 25
rate the two. Areas showing the Hastern Shore type are found along the margin of the Western Shore at intervals as far south as Herring Bay, and again from Point Lookout northwestward along the margin of the Potomac River. On the other hand, an outlier of the Western Shore type of topography is found at Grays Hill, in Cecil County, at the northern margin of the Hastern Shore. The Eastern Shore type of topography consists of flat, low, and almost featureless plains, while the Western Shore is a rolling upland, attaining four times the elevation of the former, and resembling the topography of the Piedmont Plateau much more than that of the typical Eastern Shore. It will be seen later that these two topographic types, which at once strike the eye of the physiographer as being distinctive features, are in reality not as simple as they first appear, but are built up of a complex system of terraces dissected by drainage lines.
The Coastal Plain of Maryland, with which most of the State of Delaware is naturally included, is separated from that of New Jersey by the Delaware River and Delaware Bay, and from that of Virginia by the Potomac River, but these drainage ways afford no barriers to the Coastal Plain topography, for the same types with their systems of ter- races exist in New Jersey and Virginia as well as in Maryland.
The Chesapeake Bay, which runs the length of the Coastal Plain, drains both shores. From the Western Shore it receives a number of large tributaries which are in the process of developing a dendritic type of drainage, and which have cut far deeper channels than have the rivers of the Eastern Shore. If attention is now turned to the character of the shore-line, it will be seen that along Chesapeake Bay it is extremely broken and sinuous. A straight shore-line is the exception, and in only one place, from Herring Bay southward to Drum Point, does it become a prominent feature. These two classes of shore correspond to two types of coast. Where the shore is sinuous and broken, it is found that the coast is low or marshy, but where the shore-line is straight, as from Herring Bay southward to Drum Point, the coast is high and rugged, as in the famous Calvert Cliffs which rise to a height of 100 feet or more above the Bay. The shore of the Atlantic Ocean is composed of a
—
ee
26 THE Lower CRETACEOUS DEPOSITS OF MARYLAND
long line of barrier beaches which have been thrown up by the waves and enclose behind them lagoons flushed by streams which drain the seaward slope of the Eastern Shore. |
It was stated in the early part of this chapter that the topography of the Coastal Plain is in reality more complex than at first appears, and that this complexity is due to a system of terraces out of which the region is constructed. ‘The subaérial division of the Coastal Plain con- tains four distinct terraces and part of another, while the submarine contains one only. This makes for the Coastal Plain, as a whole, a group of five terraces. These terraces, beginning with the highest, are known by the names of Lafayette, Sunderland, Wicomico, Talbot, and Recent. All five of the subaérial terraces are found on the Western Shore, while only three of them occur on the Eastern Shore. These terraces wrap about each other in concentric arrangement, and are de- veloped one above another in order of their age, the oldest standing © topographically highest.
THE GEOLOGY
The area of low land and shallow sea floor which borders the Piedmont Plateau on the east and passes with constantly decreasing elevation east- ward to the margin of the continental shelf has been described under the name of the Coastal Plain. It is made up of geological formations of late Mesozoic and Cenozoic age. These later formations stand in marked contrast to the older strata to the westward, in that they haye been but slightly changed since they were deposited. Laid down one above another upon the eastern flank of the Piedmont Plateau, when the sea occupied the present area of the Coastal Plain, these later beds form a series of thin sheets that are inclined at low angles seaward, so that successively later formations are encountered in passing from the inland border of the region toward the coast. Oscillation of the sea floor, with some variation both in the angle and direction of tilting, went on, however, during the period of Coastal Plain deposition. As a
result the stratigraphic relations of these formations, which have gen-
MARYLAND GEOLOGICAL SURVEY
raw) ~
erally been held to be of the simplest character, possess in reality much complexity along their western margins, and it is not uncommon to-find - that intermediate members of the series are lacking, as the result of transgression, so that the discrimination of the different horizons, in the absence of fossils, often requires the utmost care.
The Coastal Plain sediments were laid down after a long break in time following the deposition of the red sandstones and shales (Newark formation) of late Triassic age, which overlie the crystalline rocks of the western division of the Piedmont Plateau, and complete the sequence of geological formations found represented in Maryland and Delaware. From the time deposition opened’in the coastal region during early Cretaceous time to the present, constant sedimentation has apparently been going on, notwithstanding the fact that frequent unconformities appear along the landward margins of the different formations.
The formations consist of the following:
FORMATIONS OF THE COASTAL PLAIN.
Cenozoic. Quaternary. Recent. Pleistocene....... Rone aren Mal bourse Ment Wicomico.......... ! = Columbia Group. Sunderland......... Tertiary. : P Pliocene (7?) ..........6. Lafayette. IMM OECENER Hai aan rma sone Sty Maryiseos-riaecin. Choptank........... = Chesapeake Group. Calvienrbecsciec stone: IO COMCR ear eetis seaner a cia anesete Nanjemoy Weebl ieee i =ayprinitiicar Sete NGQUIB SE HSSh Ras weer Mesozoic. Cretaceous. Upper Cretaceous........ Rancocas. , Monmouth. Matawan. Magothy. Raritan. Lower Cretaceous........ IPATADSGOS,.\a'eres sen i
Arundel............ = Potomac Group.
———
———— Oe ae ee SO
- mag ee
28 THE Lower CRETACEOUS DEPOSITS OF MARYLAND
CRETACEOUS Lower Cretaceous
The Lower Cretaceous is represented by the Potomac Group, which consists of the Patuxent, Arundel, and Patapsco formations, deposits laid down under estuarine and fluviatile conditions. The three forma- tions have only been recognized in their full development in Maryland, the lowermost Patuxent formation not being found to the north of Maryland but extending southward as the basal division of the Coastal Plain series through the south Atlantic States to eastern Alabama, while the uppermost Patapsco formation extends northward into Pennsylvania and disappears southward in central Virginia. The Arundel formation has been recognized in Maryland alone.
The three formations are unconformable to each other and the under- lying and overlying formations. They consist chiefly of sands and clays, the former frequently arkosic, while gravel beds are found at certain points where the shoreward accumulations are still preserved. The deposits of the Patuxent formation consist mainly of sand, often arkosic, and at times argillaceous, while clay beds at times appear. The Arundel formation consists largely of clays, frequently dark coiored, and affording in places large amounts of nodular carbonate of iron. At times the deposits are very carbonaceous. ‘The Patapsco materials consist largely of highly colored and variegated clays which grade over into lighter colored sandy clays and also at times into sands.
The organic remains consist largely of fossil plants although the Arundel formation has afforded representatives of several orders of Reptilia together with a few invertebrate fossils. The fossil plants in the Patuxent and Arundel formations consist chiefly of ferns, cycads, and conifers, while the Patapsco formation contains a considerable rep- resentation of dicotyledonous types. Messrs. Berry and Lull, who have studied the plant and animal remains regard them as characteristic of the Lower Cretaceous. The fossil plants of the Patuxent and Arundel are strongly Neocomian-Barremian in character, while those of the
Patapsco are distinctly Albian.
MARYLAND GEOLOGICAL SURVEY 29
The total average thickness of the Lower Cretaceous formations in Maryland is between 600 and 700 feet, and they show an average dip of about 40 feet in the mile to the southeast.
Upper Cretaceous
The deposits referred to the Upper Cretaceous comprise the Raritan, Magothy, Matawan, Monmouth, and Rancocas formations. The two lower formations are estuarine and fluviatile in origin, while the over- lying formations are distinctly marine. All of these formations can be traced to the northward into Delaware and New Jersey, where they attain an even larger development than in Maryland. To the southward they are gradually overlapped, one after the other, by the Tertiary formations and are unknown in Virginia. Similar deposits are found in North Carolina and the States which lie to the south of it but are known under other formational names. |
The four upper formations form an apparently conformable series resting unconformably upon the Raritan formation, which in turn over- lies the Patapsco formation unconformably. A slight unconformity may perhaps exist between the Magothy and the Matawan, although a fuller study of the relation of these formations indicates that they are prob- ably conformable over the greater portion of the area of outcrop. The deposits consist chiefly of sands and clays, with some gravels in the two lower formations, while the three higher formations consist more par- ticularly of clays and sands, the latter often somewhat glauconitic, although much less so than similar deposits in New Jersey. The Rari- tan formation consists chiefly of thick-bedded and light-colored sands with some gravels. Clays generally light in color occur in the lower portion of the formation. The Magothy formation is made up of sands and clays that change rapidly both horizontally and vertically, finely laminated clays with sand layers and more or less carbonaceous often appearing. The Matawan formation is composed of micaceous, sandy clays somewhat more sandy at times in the upper portion and more argillaceous in the lower portion of the formation. The Monmouth formation consists of reddish and pinkish sands more or less glauconitic
30 THe Lower CRETACEOUS DEPOSITS OF MARYLAND
in character. The Rancocas formation, which outcrops in Delaware near the Maryland line, consists of greensand marls which are fre- quently highly calcareous.
The organic remains consist chiefly of fossil plants in the Raritan and Magothy formations, and of fossil invertebrates in the. Matawan, Monmouth, and Rancocas formations. The flora consists largely of dico- tyledonous types those forms found in the Raritan formation being dis- tinctly Cenomanian in character while those of the Magothy are ap- parently Turonian in age, which is apparently also the age of the Matawan invertebrates. The Monmouth fauna, corresponding to the Ripley fauna of the Gulf, is universally regarded as of Senonian age, while the overlying Rancocas fauna has been referred to the Danian.
The total average thickness of the Upper Cretaceous formations of Maryland is about 400 feet. They show a dip of from 20 to 35 feet in the mile to the southeast.
TERTIARY Hocene
The Eocene is represented by the Pamunkey Group, which consists of the Aquia and N anjemoy formations. The deposits are of marine origin and comprise part of a geologic province embracing Virginia, Maryland, and Delaware.
The two formations constitute a conformable series which overlies the Upper Cretaceous deposits in Maryland unconformably while in Virginia it has transgressed the latter and is found overlying the Lower Cre- taceous strata unconformably. The deposits consist chiefly of green- sands which are often calcareous in the Aquia formation and argillaceous in the Nanjemoy formation.
The fossils consist mainly of animal remains and comprise an ex- tensive fauna, embracing particularly the group of Mollusca and Anthozoa, which shows a faunal relationship with the Wilcox and probably with the lower Claiborne beds of the Gulf.
The total thickness of the Eocene deposits in Maryland is about 225
MARYLAND GEOLOGICAL SURVEY 31
feet, and they show an average dip of 124 feet in the mile to the southeast.
Miocene
The Miocene deposits of Maryland are represented by the Chesapeake Group, which is made up of the Calvert, Choptank, and St. Mary’s formations.t These formations are of marine origin. They attain a very extensive development in the drainage basin of Chesapeake Bay, both in Maryland and Virginia, from which area they can be traced southward into North Carolina and northward into Delaware and New Jersey. To the south of the Hatteras axis the conditions change materially, and other formations presenting faunal affinities more or less close are found.
The several formations comprising the Miocene are apparently slightly unconformable to each other, although this unconformity is oftentimes not apparent, the Choptank in some areas being apparently conformable to the Calvert, while the St. Mary’s seemingly presents the same rela- tions to the Choptank. The deposits of the Chesapeake Group consist largely of sands, clays, and marls. The Calvert is in part sandy and in part clayey, with extensive deposits of diatomaceous earth in the lower or Fairhaven member, and numerous marl beds packed with mol- lusean shell remains in the upper or Plum Point member. The Chop- tank formation is essentially sandy, although clays and marls also occur. The St. Mary’s formation is decidedly clayey with sands or sandy clays, the latter typically greenish-blue in color and often containing large quantities of fossils.
The organic remains consist largely of fossil invertebrates, by far the most common group being the mollusca. Diatoms are very common, and remains of land plants are not rare in the basal strata, while corals, bryozoans, and echinoderms are not infrequent. Many cetacean forms have been found at some localities.
The thickness of the Miocene deposits is between 450 and 500 feet, and the strata have an average dip of 10 feet in the mile to the southeast.
1 Another formation, the Yorktown, occurs at the summit of the Chesapeake Group in Virginia and North Carolina.
3
32 Tuer Lower Cretaceous Drposits oF MARYLAND
Pliocene ( ?)
The supposed Pliocene is represented by the Lafayette formation which has been considered as extending from the Gulf along the Atlantic border region as far northward as Pennsylvania, where the last remnants are found. The Lafayette formation is chiefly developed as a terrace. lying irregularly and unconformably on whatever older formation chances to be beneath it whether along the margin of the Piedmont Plateau or the Coastal Plain.
Few fossils have been found in the Lafayette, and those not sufficiently distinctive to determine its age. We simply know that it is younger than the latest Miocene on which it rests and older than the oldest Pleistocene beds found in its immediate vicinity. It may be either Ter- tiary or early Quaternary in age, although most authors hitherto have regarded it as probably Pliocene in age. Doubtless materials of very different ages have been referred by various students to the Lafayette. The type section in Lafayette County, Mississippi, has recently been shown to be of Hocene age.*
The materials comprising the Lafayette formation consist of clay, loam, sand, and gravel which are often highly ferruginous, the iron being often present in the deposits in sufficient amount to act as a cement. These materials are generally very imperfectly sorted. The deposits rarely exceed 50 feet in thickness, while the southeasterly dip is only a few feet in the mile.
QUATERNARY Pleistocene
The Pleistocene deposits consist of a series of surficial materials known under the name of the Columbia Group, which has been divided in Maryland and adjacent States into the Sunderland, Wicomico, and Talbot formations. They consist mainly of a series of terraces which wrap about the Lafayette and the lower portions of the older formations, and hence extend as fluviatile deposits up the stream courses. 3
1 Berry, Journ. Geol., vol. xix, 1911, pp. 249-256.
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE I!
Fic. I.—VIEW SHOWING BASAL CONGLOMERATE OF THE PATUXENT OVERLYING THE PIEDMON CRYSTALLINES AT ROLAND PARK, BALTIMORE CITY.
Fic. 2.—VIEW SHOWING PATUXENT ARKOSIC SANDS AND GRAVEL IN B. & OF RR CUA SAVAGE, ANNE ARUNDEL COUNTY.
Go
MARYLAND GEOLOGICAL SURVEY 3
Fossils have been found particularly in the latest, or Talbot forma- tion, where extensive shell beds of estuarine and marine origin are known. Fossil plants have been found in all the formations. Their general similarity has made it impossible to establish distinctive floras as a basis for the correlation of the several formations, which has been based mainly on physiographic grounds.
The materials consist of clay, loam, sand, gravel, peat, and ice-borne boulders. These do not as a rule occur in very definite beds, but grade into each other both vertically and horizontally. The coarser materials are often cross-bedded, and are for the most part distinctive over the lower portion of each of the formations, while the finer materials, par- ticularly the loam, are commonly found in the upper part of the forma- tions, although these conditions are by no means universal. Each of the ‘formations rarely exceeds 25 or 30 feet in thickness, although under exceptional conditions a thickness of two or three times that amount occurs.
Recent
The Recent deposits embrace chiefly those being laid down to-day over the submarine portion of the Coastal Plain, and along the various estu- aries and streams. ‘T’o these must also be added such terrestrial deposits as talus, wind-blown sand, and humus. In short, all deposits which are being formed under water or on the land by natural agencies belong to this division of geological time.
The Recent terrace now in process of formation along the ocean shore-line and in the bays and estuaries is the most significant of these deposits, and is the latest of the series of terrace formations which began with the Lafayette, the remnants of which to-day occupy the highest levels of the Coastal Plain, and which has been followed in turn by the Sunderland, Wicomico,.and Talbot.
A deposit of almost universal distribution in this climate is the humus or vegetable mold, which being mixed with the weathered surface of the underlying rocks forms our agricultural soils. The intimate relation- ship therefore of the soils and underlying geological formations is evi- dent.
34 THE Lower CRETACEOUS DEPOSITS OF MARYLAND
Other accumulations in water and on land are going on about us all the time, and with those already described represent the formations of Recent time.
HISTORICAL REVIEW
The more detailed and specific discussions of the Potomac Group and its contained fossils, as is usually the case, were preceded by a long period during which the geological and lithological relations chiefly at- tracted attention, and this in turn was preceded by a still longer period during which the subjects were still more general, and only passing reference was made to the series of strata since designated the Potomac Group.
The earliest definite reference to rocks of this age is contained in two papers by B. H. Latrobe, the first of which dates back to 1799 and refers to the use of “ Rappahannoc freestone” in the construction of the lighthouse at Cape Henry. The second paper, published in 1809, de- scribes this rock and its uses, and mentions the presence of the contained wood and lignite from the vicinity of Fredericksburg, Virginia.
The paper by John Finch, read before the Philadelphia Academy in 1823, and so often cited in historical discussions of Coastal Plain geology, mentions the organicaremains in the clay underlying the diluvial gravel at Washington, and although not altogether unequivocal probably refers to Potomac strata. Morton’s paper of 1829, which was based on the notes of Vanuxem, describes the lignite and charred wood of these rocks, which they include in their “ Secondary formation.”
The first intimation of the wide extent of the Potomac formations is contained in an early report of Edward Hitchcock, published in 1833, in which he mentions the probable distribution of deposits of this age from Cape Cod to the Gulf of Mexico.
In a paper published by Thomas G. Clemson in 1835 there is a good description of the Potomac material near Fredericksburg with its fossil wood and lignites, and with the first reference to impressions of plants which he says are finely preserved in blue argillaceous fissile beds from six inches to a foot in thickness.
MARYLAND GEOLOGICAL SURVEY 35
Richard C. Taylor, in a paper immediately following that of Mr. Clemson devotes six pages and a folded plate to the description and illustration of these plants, which he identified as Lycopodiolithes ? sp., Lepidodendron sp., Sphenopteris sp., Pecopteris ?sp., and Thuites ? sp., and which are the remains of Frenelopsis, Sphenolepis, Cladophlebis, ete. These he saw bore no relation to the plants from the Richmond coal field, which were attracting considerable attention at that time and he infers that the containing rocks are of Secondary age, perhaps co-eval with the oolites.
The year 1835 also marks the beginning of the important series of reports on the geology of Virginia by William B. Rogers, State Geologist of that State, the first describing the Potomac sandstones along the “ Fall-line ” and mentioning the presence of siljcified wood, lignite, and plant impressions. In his report for 1839 the same author traces his “ Sandstone formation ” as far south as Bollings Bridge on the Nottaway River in southern Virginia. In his next report, that for 1840, he desig- nates this formation the “Upper Secondary,” and traces its extent northward from Petersburg to the Potomac River. Later reports also frequently refer to these rocks, which he regarded as Upper Oolite in age.
Richard C. Taylor returns to this subject in his work on the Statistics of Coal, published in 1848, and compares the organic remains to those from the Portland of southern England.
With the appointment of Philip T. Tyson to be State Agricultural Chemist of Maryland, the latter State enters the literature. The map accompanying his first report enumerates twenty-four formations, of which the Cretaceous includes two, the first “a thick group of sands and clays of various colors.” “In some localities it abounds in lignite derived from coniferous plants.” “The bluish-gray varieties derive their color from the carbonaceous remains of plants ”; the second, or Iron-ore clays, “a series of beds of fine gray and lead-colored clays containing several courses of carbonate of iron in flattened masses and nodules.” “The color of these clays is due to carbonaceous matter.”
Tyson early discovered a saurian tooth in the latter beds, which was described under the generic name Astrodon by Christopher Johnston in
36 THe Lower CRETACEOUS DEPposiIts oF MARYLAND
1859, and more fully described by Professor Joseph Leidy in 1865. From the same bed which yielded the tooth Tyson records “a new genus of Cycas of large dimensions,” “ silicified coniferous wood,” and “ lignites (coniferous).” In his next report, published in 1862, Tyson discusses these iron-ore clays and says he is disposed to place them as low as the oolitic, which view is concurred in by Agassiz, to whom he had showed a photograph of the cycad trunk. Tyson found a number of these cycad trunks and sent pictures of them to various geologists. ‘They are men- tioned by Professor Dana in the first edition of his Manual, with the comment that P. T. Tyson observes that they may be Upper Jurassic. One trunk was presented to Professor Dawson and is still at Montreal, another was presented to Professor Marsh and is now in the Yale College collection, while a third turned up recently at the South Carolina Col- lege at Columbia, probably a gift by Tyson to Professor Le Conte, who at that time was located at Columbia. The others were for a long time in the possession of the Maryland Academy of Sciences, which institution eventually turned them over to the Johns Hopkins University where they are at the present time. Professor Dawson sent one of Tyson’s photo- graphs to Carruthers, who refers to it in a postscript to his memoir “ On Fossil Cycadean Stems from the Secondary Rocks of Britain,” pub- lished in 1870.
Professor Cope in a paper read before the Philadelphia Academy in 1868, sketches the geology of the Cretaceous as developed from New Jersey to Virginia, mentioning the cycadaceous plants of Tyson, and also referring to the clays along the Rappahannock from which Professor Uhler has obtained the “ remains of some six species of plants, in beau- tiful preservation, of the order Cycadacee ?, Gnetacee, and Filices.” This was probably the Fredericksburg plant locality which afterward re- warded Professor Fontaine’s efforts with such a great variety of speci- mens. Professor Cope states that it is extremely probable that these Virginia beds are the continuation of those of Maryland and Alexandria, and he proceeds to sketch the conditions of deposition comparing them to the conditions which prevailed to the westward in Triassic times. He says further: “The age is therefore probably truly Wealden or Neo- comian.”
MARYLAND GEOLOGICAL SURVEY 37
Among other “Geological Notes” presented to the Boston Society of Natural History in 1875 by W. B. Rogers is a paper “ On the Gravel and Cobblestone Deposits of Virginia and the Middle States,” in which he clearly distinguishes the surficial gravels of the Lafayette and Colum- bia from those of the older Potomac. “In the belt partially occupied by the surface deposit here referred to there is exposed another group of strata with which, at first view, the sandy and argillaceous layers of this formation might readily be confounded. These are the silicious, argillaceous, and pebbly beds, which, underlying the Tertiary in Virginia, and the well-marked Cretaceous formation farther north, have, in the latter region, been regarded as belonging to the base of the Cretaceous series of the Atlantic States. In Virginia the formation consists typically of a rather coarse and sometimes pebbly sandstone, in which the grains of quartz and feldspar are feebly cemented by kaolin, derived from the decomposition of the latter, and of argillaceous and silicious clays vari- _ ously colored and more or less charged with vegetable remains, either silicified or in the condition of lignite. These constitute the group of beds designated in the Virginia geological reports as the Upper Second- ary sandstone, and referred by me long since (1542) to the upper part of the Jurassic series, corresponding probably to the Purbeck beds of British geologists. From the Potomac northward this group of deposits, as exposed in the deep railroad cuts between Washington and Baltimore and on to Wilmington, is made up of variegated, soft, argillaceous, and silicious beds, which, from the preponderance of ferruginous coloring toward the Delaware, has been called by Professor Booth the red clay formation. At a few points only toward the bottom of the deposit it brings to view a bed of the felspathic sand, or crumbling sandstone, above referred to. Traced transversely, it is seen to dip beneath the Cretaceous greensand at various points in New Jersey, Delaware, and Maryland, but in Virginia disappears in its eastward dip beneath the Eocene Ter- tiary.
“How far we may consider this group of sediments in Maryland, Delaware, and New Jersey as merely a continuation of the Virginia for- mation above described can be determined only by further investigation.
38 THe LoweR CRETACEOUS Deposits oF MARYLAND
But the discovery in them at Baltimore, by Professor Tyson, of stumps of cycads would seem to bring them into near relation with the formation at Fredericksburg containing similar remains, and to favor their being referred, at least in part, to the horizon of the upper Jurassic rocks. Possibly we may find here a passage group analogous to the Wealden of British geology. Whatever may be the result of further discovery, it would seem to be premature at this time to assume the whole of these deposits from the Potomac northward as belonging to the Cretaceous series.
“‘ Where the Tertiary or Cretaceous rocks are present in this belt there is, of course, no danger of confounding the superficial gravel and cobble- stone deposit with the formation just described, but in their absence, which is usual in the river valleys, this deposit rests immediately on the broken and denuded surface of the Secondary, and by the inter- mixture of materials makes it more difficult to discriminate between them.
* Excellent opportunities for observing the contact of the superficial — deposit with the denuded and much older formation below are presented in the neighborhood of Washington, among which may be specially men- tioned the vertical cut at the extremity of Sixteenth street, at the base of the hill occupied by Columbian College, and also the continuation of Fourteenth street, ascending the same hill. At the former locality the crumbling felspathic sandstone, or slightly adhering sand, is exposed to a height of about 35 feet, with a very gentle eastern dip, and having the color, composition, and diagonal bedding characteristic of the Fredericks- burg and Aquia Creek sandstone. The gravel and cobblestone deposit lying upon it descends with the slope of the hill to the general plain below, resting at a somewhat steep angle against the denuded edges of the underlying beds. From this and other localities it becomes obvious that the latter formation has been deeply and extensively denuded before and during the deposition of the surface strata, which form the chief subject of this communication.”
Professor Fontaine commenced his work on the Potomac at about ie time, publishing during 1879 a series of three articles in the American
MARYLAND GEOLOGICAL SURVEY 39
Journal of Science entitled Notes on the Mesozoic of Virginia, and in- eluding the Triassic in his discussion. The flora received considerable attention and the materials were grouped into the “ Fredericksburg belt ” and the “ Petersburg belt,” the one corresponding with what he after- ward called the Fredericksburg beds and the other answering to the James River beds, both in large part referable to the Patuxent forma- tion. It was in the part published in the February number of the Ameri- can Journal of Science that the “ archaic dicotyledons” of the Potomac were first mentioned in the following language: “ With the plants above named, I find certain netted veined leaves, which by their nervation can- not be distinguished from Angiosperms. Had they been found with Cretaceous or Tertiary plants I think no one would hesitate to consider them as such. As, however, they occur with a well-marked upper Juras- sic flora, I hesitate to pronounce them to be Angiospermous plants with- out a more careful study and extended comparison than I have as yet been able to make. They are certainly not ‘ Dictyophyllum,’ which is the genus of fossil ferns that stands nearest to them. But when we find such a development of undoubted Angiosperms in the lowest Cretaceous beds of New Jersey and of the west, we should expect to find at least their ancestors in the Jurassic flora.” Further along he speaks of the evidence as to the age of the iron-ore clays as pointing strongly to the conclusion that they were Wealden.
In a lecture by Professor Uhler, an abstract of which was published in 1883, considerable space was given to what is now regarded as part of the Potomac Group, and which he calls Upper Jurassic or Wealden, giving it a thickness of 500 feet in the Baltimore region.
In the spring of 1884 Professor Ward prepared a short paper on Mesozoic Dicotyledons, in which he mentions Fontaine’s archaic dicotyle- dons, which he states are from the Upper Jurassic of Virginia, and ex- presses the hope that the problem of the origin of this group is at last approaching solution. About this time Professor Fontaine joined the staff of the U. S. Geological Survey, his first administrative report ap- pearing in 1885 in the Sixth Annual Report.
In 1886 the name Potomac formation first appeared in print in a paper
40 THe Lower CRETACEOUS Deposits oF MARYLAND
contributed by W J McGee to the Report of the Health Officer of the District of Columbia for 1885. In 1887 Professor Fontaine submitted a paper embodying his results to the American Association for the Ad- vancement of Science, a brief abstract of which was published in 1888, from which the following is quoted: “The name Potomac formation has been applied to a series of newer Mesozoic sands, gravels, and clays, sometimes cemented into sandstones and conglomerates, which appear along the inner margin of the Coastal Plain, forming the basal member of the undisturbed Mesozoic and Cenozoic formations of the eastern United States, in Virginia, Maryland, Delaware, and perhaps other States. It comprises two members—an upper, consisting generally of variegated clays which are well exposed about Baltimore, and a lower, consisting predominantly of sands and gravels, well exposed in the bluffs of the Potomac River below Washington. The upper member is known only north of Fredericksburg, and the lower is best developed from Washington to Richmond. ~
“ The age of the formation, as indicated by its flora, appears to coin- cide approximately with that of the Lower and Middle Neocomian [| mis- printed Neuronian] of Greenland and Europe.”
It was in December, 1887, that Mr. J. B. Hatcher, under instructions from Professor O. C. Marsh, collected a considerable number of verte- brate bones from an iron mine near Muirkirk, Md. He also found in the same beds some small cones representing the genus Sequoia, and much silicified wood and lignite. The bones were described by Professor Marsh and the results published at once. As to the geological signifi- cance of these forms, Professor Marsh says:
“The fossils here described, and others from the same horizon, seem to prove conclusively that the Potomac formation in its typical localities in Maryland is of Jurassic age, and lacustrine origin. There is evidence that some of the supposed northern extensions of this formation, even if of the same age, are of marine or estuary origin.”
The next year Professor Uhler read a paper before the American Philosophical Society in which the name Baltimorean was proposed for the lower beds and Albirupean for the upper, which, however, included
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE III
Fic. I.—VIEW SHOWING COARSE, HIGHLY INCLINED AND CROSS-BEDDED PATUXENT SANDS NEAR HOMESTEAD, BALTIMORE CITY.
FIG. 2.—VIEW SHOWING KAOLIN IN THE PATUXENT FORMATION IN CUT ON P. B. & W.R. R. NEAR PERRYVILLE, CECIL COUNTY.
MARYLAND GEOLOGICAL SuRVEY 41
strata younger than the Potomac. He enumerated the various types of _ plant remains which he had collected from the different horizons.
The same year McGee published his paper entitled “ Three Formations of the Middle Atlantic Slope,” devoting much of his space to the Po- tomac formation, erroneously referring the Bryn Mawr gravels, the
”” east
“yellow rocks,” above Trenton, New Jersey, and the “sand hills of Princeton, New Jersey, to the Older Potomac. |
At the meeting of the National Academy of Sciences held in the spring of 1888 Professor Ward prepared a paper on the “ Evidence of the fossil plants as to the age of the Potomac formation,” which was published in the August number of the American Journal of Science, from which the following may be quoted:
““On numerous occasions, dating as far back as 1878, I have expressed the opinion that the dicotyledons could not have had their origin later than the middle Jura, and it will not surprise me if the final verdict of science shall place the Potomac formation, at least the lower member in which the plants occur, within that geologic system. While the re- maining types point strongly in this direction, I do not regard the dicotyledons as at all negativing, but even more strongly suggesting, this view.
“Still, it may be admitted that, according to the ordinary modes of arguing from similar statistics, the sum of all the facts here presented would make the Potomac, considered from the view of the flora aloue, homotaxially equivalent to the Wealden of England and north Germany, now usually included in the Cretaceous system. If the vertebrate re- mains are Jurassic and the flora Cretaceous we only have here another confirmation of a law exemplified in so many other American deposits, that, taking European faunas and their correlated floras as the standard of comparison, the plant life of this country is in advance of the animal life. This law has been chiefly observed in our Laramie and Tertiary deposits, but is now known to apply even to Carboniferous and De- vonian floras. It is therefore to expected that we shall find it to prevail during the Mesozoic era. If, therefore, it be really settled that the fauna of the Potomac series is homotaxially Jurassic, and we take our
42 THE Lower CRETACEOUS DeEposiTs oF MARYLAND
starting point from the Old World geology, there will be no more ob- jection to regarding the Potomac flora as Jurassic than there is now in contemplating the Laramie flora as Cretaceous. In fact, so far as the character of the flora is concerned, there is much less difficulty in the ease of the Potomac than in that of the Laramie, since, as I have shown, the Potomac flora, viewed in all its bearings, cannot be said positively to negative the reference of the formation to the Jurassic upon the evi- dence of the plants alone.
“T do not, however, desire to be understood as arguing for the Juras- sic age of the Potomac formation. The most that it is intended to claim is that, if the stratigraphical relations and the animal remains shall finally require its reference to the Jurassic, the plants do not present any serious obstacles to such reference.”
European paleobotanists having manifested much interest in the Potomac flora, a statement was prepared by Professor Fontaine for Feist- mantel, the celebrated Bohemian savant who made it the subject of a paper which appeared in the proceedings of the Royal Bohemian Society in 1889. This same year saw the appearance of Dr. Knowlton’s long- delayed work on the fossil wood and lignites of the Potomac formation, a summary of which he had already contributed to the 1888 meeting of the American Association for the Advancement of Science, an abstract also appearing in the American Geologist. Professor Uhler also pub- lished two additional papers at this time announcing the finding of his Albirupean formation at Ft. Foote and on Piscataway Creek.
In 1890 Professor Fontaine’s Monograph was issued. In it are de- scribed and illustrated 365 species, so called, of fossil plants, including 75 more or less nominal species of dicotyledons. The age is assumed to be Neocomian, under which term are included the Wealden, Urgonian, and Aptian groups of European geologists. _
In Professor Clark’s account of the “Third Annual Geological Expe- dition into Southern Maryland and Virginia,” published in 1890, the Albirupean is recognized as distinct from the underlying Potomac. The same year N. H. Darton discussed the Potomac in a paper read before the Geological Society of America, and the literature to date was passed
MARYLAND GEOLOGICAL SURVEY 43
in review by Dr. C. A. White in his Correlation Paper on the Cretaceous, published in 1891.
Nearly twenty years after Tyson’s discovery of cycad trunks in the iron-ore beds of Maryland, Mr. Arthur B. Bibbins took up the quest, and during the next few years succeeded in obtaining from the inhabitants of the region a very large number of trunks and fragments. These were submitted for critical study to Professor Ward, who in 1894 published a revision of the genus Cycadeoidea, to which all of the Maryland forms belonged. Mr. Bibbins continued to collect more material, and in 1897 Professor Ward published descriptions of seven species from Maryland.
In a paper entitled “ Albirupean Studies,” and published in 1892, Professor Uhler makes further contributions to the knowledge of the Potomac, but his stratigraphic conclusions are, according to Professor Ward, set forth in a rather ambiguous manner.
In a paper in Science, published in 1894, Professor Ward makes an interesting comparison between the Potomac flora and that from the Mesozoic of Portugal made known by the Marquis Saporta. He suggests the following long-range correlations: James River beds=Infra Valan- ginian, Fredericksburg beds= Valanginian, Mount Vernon beds=Ur- gonian, Brooke beds= Aptian, and Raritan beds=Albian. In the same number of Science appeared a note by F. A. Lucas on the Vertebrate re- mains from the Maryland Potomac, Allosaurus, Pleuroccelus, Priconodon and Astrodon being the forms enumerated. The same year Mr. Bibbins published a summary of his Potomac studies, and the Fredericksburg folio of the U. 8. Geological Survey by N. H. Darton was issued. It included a large area of the Virginia Potomac, which was described and mapped as a single unit, however.
A number of important papers appeared during 1896. Among these are Professor Ward’s elaborate discussion entitled: “'The Potomac For- mation,” in which he subdivides it into The James River Series, The Rappahannock Series, The Mount Vernon Series, The Aquia Creek Series, The Iron Ore Series, The Albirupean Series, and the Island Series. The flora of each is discussed and considerable space is devoted to the newly discovered flora of the clays on the Mt. Vernon estate.
44 THE Lower CRETACEOUS DEposits oF MARYLAND
This was followed by Professor Marsh’s memoir on “The Dinosaurs of North America,” which contained the descriptions and figures of the Maryland material collected from the iron-ore clays by J. B. Hatcher. At the same time appeared Professor Ward’s paper on “‘ Some Analogies in the Lower Cretaceous of Europe and America,” in which the Potomac was compared with the Wealden of England, the “ Scaly Clays” of Italy, and the Mesozoic of Portugal. Toward the close of the year Professor Fontaine’s long-delayed geological paper on the Potomac appeared as a Bulletin of the U. 8. Geological Survey. It contained admirable de- scriptions of local sections and the first geological map of the deposits, covering the country between Baltimore and Petersburg. No attempt was made, however, to show the areal extent of the subdivisions of the Potomac, and the Virginia deposits are regarded as Lower and those in Maryland as Upper Potomac. Professor Newberry’s monograph on the Amboy clay flora appeared at this time as a posthumous publication un- der the editorship of Arthur Hollick.
About this time Professor Marsh published two brief papers asserting the Jurassic age of the Potomac as well as of the Cretaceous beds on Long Island and to the eastward. This called forth a discussion in the col- umns of Science which was participated in by Arthur Hollick, L. F. Ward, G. K. Gilbert, R. T. Hill, and Jules Marcou.
In the fall of 1897 Clark and Bibbins published a full summary of the results arrived at in their study of the Potomac of Maryland, dividing it into four formations—the Patuxent, Arundel, Patapsco, and Raritan. The two former formations were provisionally referred to the Jurassic and the two latter to the Lower Cretaceous.
In 1898 Professor Marsh replied to his critics and reasserted the Juras- sic age of the Potomac beds.
In 1902 Clark and Bibbins published a second paper on the Potomac of Maryland, in which the conclusions are essentially the same as in their earlier paper. This paper was well illustrated and contained an admirable map showing the areal extent of the different members of the Potomac Group as developed in Maryland, the first of its kind ever published. This same year the Cecil County report of the Maryland
MARYLAND GEOLOGICAL SURVEY 45
Geological Survey appeared. The Coastal Plain geology was contributed by G. B. Shattuck, that for the Potomac largely from Mr. Bibbins’ notes. The three Potomac formations present in that region, the Patuxent, Patapsco, and Raritan, are delineated upon the large scale county map.
In 1906 the Dover folio of the U. 8. Geological Survey prepared by Dr. B. L. Miller was published. This included a considerable area in Delaware and northeastern Maryland, in which the Patapsco and Raritan formations were described and mapped. .
Although it bears the date 1905 it was in 1906 that Ward’s second paper on the Status of the Mesozoic Floras of the United States was issued. Over two hundred and fifty pages are devoted to the Potomac flora of Maryland and Virginia, two additional species of Maryland eyead trunks are described, and the large amount of material collected by Mr. Bibbins for the Maryland Geological Survey and Goucher College is discussed in the systematic part prepared by Professor Fontaine. The correlations and stratigraphy are by Ward, who accepts the Maryland Survey formational names for that State, uniting, however, the Patuxent and Arundel formations. For Virginia the James River and Rappahan- nock are united and made the equivalent of the Patuxent and Arundel, and the Mount Vernon and Brooke beds are correlated with the Patapsco formation and an excellent map prepared by Mr. Bibbins shows the distri- bution of the four formations of the Potomac Group in Maryland. Pro- fessor Ward’s final conclusion was that the whole Potomac Group is of Cretaceous age, the older Potomac forming a part of the Huropean Wealden, which he regards as Cretaceous. The report on the Physical Features of Maryland by Clark and Mathews, published this same year, contained a new geological map of the State on which the different - Potomac members are shown, and the text contained a full description and characterization of them.
In 1907 the Patuxent Folio of the U. S. Geological Survey was pub- lished by Shattuck, Miller and Bibbins. All the members of the Potomac Group are fully described and mapped.
In 1910 Berry published a short article in the Journal of Geology showing that the Raritan formation was of Upper Cretaceous age. This
THE Lower CRETACEOUS DEPosITsS oF MARYLAND
46
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MARYLAND GEOLOGICAL SURVEY 47
same year Clark published a paper describing the progress of the work on the Geology of the Middle and Northern Atlantic Coastal Plain, in which the various formations were briefly discussed and the Lower Cre- taceous age of the Patuxent and Arundel formations affirmed. The Raritan was referred to the Upper Cretaceous and the Potomac Group was limited to the Lower Cretaceous. Berry also published a brief paper discussing the southward extension of the Patuxent formation into North Carolina, and showing that the Arundel formation is absent in Virginia, and that the Patapsco formation is transgressed and disappears in cen- tral Virginia beneath Tertiary deposits. The latter author also pub- lished several systematic papers upon some of the more important genera of Potomac plants.
The accompanying table shows the varying nomenclature of the more important students of the Potomac deposits, commencing with that of W. B. Rogers in 1841.
BIBLIOGRAPHY 1799 Latrope, B. Henry. Memoir on the sand hills of Cape Henry in Virginia. Trans. Amer. Philos. Soc., vol. iv, 1799, pp. 439-448, Philadelphia. 1809
Latrose, B. H. An account of the freestone quarries on the Potomac and Rappahannoc rivers.
Trans. Amer. Philos. Soc., vol. vi, part ii, 1809, pp. 283-293. | : 1824
Fincu, JoHN. Geological Essay on the Tertiary Formations in Amer- ica. (Read Acad. Nat. Sci. Phila., July 15, 1823.)
Amer. Jour. Sci., vol. vii, 1824, pp. 31-43.
1829
Vanuxem, L., and Morton, S. G. Geological Observations on Sec- ondary, Tertiary, and Alluvial formations of the Atlantic coast of the United States arranged from the notes of Lardner Vanuxem.
Jour. Acad. Nat. Sci., Phila., vol. vi, 1829, pp. 59-71. 4
48 Tue LowEr Cretaceous Deposits oF MARYLAND
1833 Hircucock, Epwarp. Report on the Geology, Mineralogy, Botany, and Zoology of Massachusetts. Amherst, 1833, pp. 201-202. 1835 Ciemson, THomas G. Notice of a geological examination of the country between Fredericksburg and Winchester, in Virginia, including the gold region. Trans. Geol. Soc. Pa., vol. i, pt. 2, Phila., 1835, pp. 298-313, pl. xvii. TayLor, RicHarD C. Review of geological phenomena, and the de- ductions derivable therefrom, in two hundred and fifty miles of sections in parts of Virginia and Maryland; also notice of certain fossil acotyledo-
nous plants in the Secondary strata of Fredericksburg. Trans. Geol. Soc. Pa., vol. i, pt. 2, Phila., 1835, pp. 314-325, pls. xviii-xix.
1836 Rogers, Witt1AmM B. Report of the Geological Reconnaissance of the State of Virginia, made under the appointment of the board of public works. Phila., 1836, p. 61. t 1840 Rogers, Witt1aAm B. Report of the Progress of the Geological Survey of the State of Virginia for the year 1839. Richmond, 1840. 1841 Rogers, WILLIAM B. Report of the Progress of the Geological Survey of the State of Virginia for the year 1840. Richmond, 1841. 1844 Rogers, H. D. Address delivered at the Meeting of the Association
of American Geologists and Naturalists. Amer. Jour. Sci., vol. xlvii, 1844, pp. 1387-160, 247-278.
1855 TayLor, RicHarp C. Statistics of Coal, 2d Ed. Phila., 1855, p. 299.
MAryYLAND GroLocicaAL Survey 49
1859
JOHNSTON, CHRISTOPHER. Am. Journ. Dental Science, N. S., vol. ix, Phila., 1859, p. 341
1860 Tyson, P. T. First Report of Philip T. Tyson, State Agricultural chemist, to the House of Delegates of Maryland, Jan., 1860. S8vo. 145
pp. Annapolis, 1860. Maps. Md. Sen. Doc. [E]. Md. House Doe. [C].
1865
Leripy, JOSEPH. Smith. Cont. to Knowledge, No. 192, vol. xiv, article vi, 1865, p. 102, pl. xiii, figs. 20-23; pl. xx, fig. 10. 1868 ~Copz, E. D. On the discovery of the fresh-water origin of certain deposits of sand and clay in west New Jersey. Proc. Acad. Nat. Sci., Phila., vol. xx, 1868, pp. 157-158.
Maury, M. F. Physical survey of Virginia. Richmond, i, 1868, 8°, 90 pp.; ii, 1878, 8°, 142 pp. 1875 Rogers, W. B. On the Gravel and Cobblestone Deposits of Virginia
and the Middle States. Proc. Boston Soc. Nat. Hist., vol. xviii, 1875, pp. 101-106.
1876 HotcHkxiss, JED. Virginia: a geographical and political summary, embracing a description of the State, its geology, soils, minerals, climate, etc. Richmond, 1876, 8vo, pp. iv, 319, and 4 maps. 1878 Hetnricu, O. J. The Mesozoic formation in Virginia. Trans. Am. Inst Min. Engs., vol. vi, 1878, pp. 227-274.
1879
Fontainrt, Wm. M. Notes on the Mesozoic of Virginia. Am. Journ. Sci., 3d. ser., vol. xvii, 1879, pp. 25-39, 151-157, 229-239.
50 Tuer Lower CRETACEOUS DEPOSITS OF MARYLAND
1881
NEWBERRY, J. S. American Cretaceous Flora. Nature, vol. xxiv, 1881, pp. 191, 192.
1883
UuHLeER, P. R. Geology of the Surface Features of the Baltimore Area.
Johns Hopkins Univ. Circ., vol. ii, Feby., 1883, pp. 52-53. (Abst.) Science, vol. i, 1883, pp. 75-76, 277.
1884 Rogers, WILLIAM Barton. A Reprint of Annual Reports and other Papers, on the Geology of the Virginias, by the late William Barton
Rogers. New York, 1884.
Warp, Lester F. On Mesozoic Dicotyledons. Am. Journ. Sci., 3d ser., vol. xxvii, 1884, pp. 292-303.
1885 McGrz, W J. Geological Formations underlying Washington and Vicinity. : Rept. Health Officer of the District of Columbia for the year ending June
30, 1885, by Dr. S. Townsend, pp. 19-21, 23-35. (Abst.) by author in Am. Journ. Sci., 3d ser., vol. xxxi, 1886, pp. 473-474.
1886
NEWBERRY, J. S. On the Cretaceous Flora of North America. Proc. Am. Assn. Adv. Sci., vol. xxxv, 1886, p. 216.
1887 Fontaine, W. M. The Flora of the Potomac Formation in Virginia. Proc. Am. Assn. Adv. Sci., 36th meeting, New York, 1887, Salem, 1888, pp. 275-276. 1888
MoGzz, W. J. Three formations of the Middle Atlantic Slope.
Am. Journ. Sci., 3d ser., vol. xxxv, 1888, pp. 120-143, 328-330, 367-388, 448- 466, pls. 2 and 6. :
Marcou, Jutes. American Geological Classification and Nomencla- ture.
75 pp., Cambridge, Mass., 1888.
MARYLAND GEOLOGICAL SURVEY 51
MarsuH, O. C. Notice of a new genus of Sauropoda and other dino-
saurs from the Potomac formation. Am. Journ. Sci., 3d ser., vol. xxxv, 1888, pp. 89-94, 9 text figs.
Unter, P. R. Sketch of the history of the Maryland Academy of Sciences.
Trans. Md. Acad. Sci., vol. i, 1888, pp. 7-8.
Warp, Lester F. Evidence of the fossil plants as to the age of the
Potomac formations. | Am. Journ. Sci., 3d ser., vol. xxxvi, 1888, pp. 119-131.
1889
FEISTMANTEL, OTtoKaR. ,Ueber die bis jetzt altesten dikotyledonen Pflanzen der Potomac-Formation in N. America, mit brieflichen Mit- theilungen von Prof. Wm. M. Fontaine.
Sitzb. k. bohm. Ges. d. Wiss., Jahre., 1889, vol. i, pp. 257-268.
Ueber die bis jetzt geologisch altesten Dikotyledonen. Zeitsch. deutsch. geol. Ges., Berlin, vol. xli, 1889, pp. 27-34. KNowLton, FRANK Hat. Fossil wood and lignite of the Potomac
formation.
Bull, U. S. Geol. Surv. No. 56, 1889, 72 pp., 7 pl. (Abstract) Amer. Assn. Adv. Sci., Cleveland, 1888, Salem, 1889, pp. 207-208. Am. Geol., vol. iii, 1889, pp. 99-106.
1890 Fontaine, Wittiam Morris. The Potomac or Younger Mesozoic
Flora. Mon. U. S. Geol. Surv., vol. xv, 1889, text, xiv, x, 377 pp.; atlas, 180 pls. Reviewed, Am. Journ. Sci. (iii), vol. xl, 1890, pp. 168, 169.
Unter, P. R. Additions to observations on the Cretaceous and Eocene
formations of Maryland. Trans. Md. Acad. Sci., vol. i, 1889-1890, pp. 45-72
Notes and illustrations to “ Observations on the Cretaceous
and Eocene formations of Maryland.” Trans. Md. Acad. Sci. vol. i, 1890, pp. 97-104.
Warp, Luster F. The Potomac or Younger Mesozoic Flora by Wm.
Fontaine. (Review.) Am. Journ. Sci. (iii), vol. xxxix, 1890, p. 50.
52 THe Lower Cretaceous Deposits oF MARYLAND
1891 * Darton, N. H. Mesozoic and Cenozoic formations of eastern Vir-
ginia and Maryland.
Bull. Geol. Soc. Am., vol. ii, 1891, pp. 431-450, pl. xvi. (Abst.) Am. Geol., vol. viii, 1891, p. 185; Am. Nat., vol. xxv, 1891, p. 658.
Wuits, CHarites A. Correlation Papers, Cretaceous. Bull. U. S. Geol. Surv., No. 82, 1891, pp. 88-92.
Witiiams, Gro. H. (Hditor.) Geological Map of Baltimore and Vicinity. Published by the Johns Hopkins University on the topographic base of the U. S. Geological Survey. 234 x 24, contour 20 feet, 18 colors, Scale 1/62,500. (J. H. U.)
, and CLrarK, Wm. B. Report on short excursions made by
the Geological Department of the University during the autumn of 1891. Johns Hopkins Univ. Cir. No. 95, vol. xi, 1892, pp. 37-39.
Guide to Baltimore, with an account of the Geology of its environs and three maps.
1892
Unter, P. R. Albirupean studies. Trans. Md. Acad. Sci., vol. i, 1892, pp. 185-201.
1893 McGes, W J. With the collaboration of G. H. Williams, Bailey Willis, and N..H. Darton.
Compte-Rendu de la 5me sess. Congrés Géol. Inter, Washington, 1891; Washington, 1893, pp. 219-251.
1894 Ciark, Wm. Buttock. The Climatology and Physical Features of Maryland. 1st Biennial Rept. Md. State Weather Service, 1894.
Darton, N. H. Artesian Well Prospects in Hastern Virginia, Mary- land, and Delaware. Trans. Amer. Inst. Min. Eng., vol. xxiv, 1894, pp. 372-397, pls. 1 and 2. |
Fredericksburg Folio. Explanatory sheets. U. S. Geol. Surv. Geol. Atlas, folio No. 18, Washington, 1894.
MARYLAND GEOLOGICAL SURVEY 53
Warp, Lester F. Fossil cycadean trunks of North America, with a revision of the genus Cycadeoidea Buckland. Proc. Biol. Soc. Wash., vol. ix, 1894, pp. 75-88. Recent discoveries of cycadean trunks in the Potomac forma- tion of Maryland. Bull. Torrey Club, vol. xxi, 1894, pp. 291-299.
1895
Bissins, ArtHur. Notes on the paleontology of the Potomac forma- tion.
Johns Hopkins Univ. Circ., vol. xv, No. 121, 1895, pp. 17-20, 1 pl.
Know tron, F. H. The oldest dicotyledons.
Popular Science News, vol. xxix, 1895, pp. 49-51, 66-68, 20 text figs.
Lyman, BrngaMIN SmirH. Report on the New Red of Bucks and Montgomery Counties.
Pa. State Geol. Summ. Final Rept., vol. iii, pt. 2, 1895, pp. 2634-2635.
Warp, Lester F. The Mesozoic flora of Portugal compared with that of the United States. ' Science, N. S., vol. i, 1895, pp. 337-346.
The Potomac Formation. Fifteenth Ann. Rep. U. S. Geol. Surv., 1895, pp. 307-397, pls. ii-iv.
1896 Darton, N. H. Artesian Well Prospects in the Atlantic Coastal Plain Region. Bull. U. S. Geol. Surv. No. 138, 1896, 228 pp., 19 pl. House Mise. Doc., 54th Cong., 2d sess., vol. —, No. 28.
Fontaine, WiLtL1AM Morris. The Potomac formation in Virginia. Bull. U. S. Geol. Surv., No. 145, 1896, 149 pp., map.
GILBERT, G. K. Age of the Potomac formation. Science, N. S., vol. iv, 1896, pp. 875-877.
Hitz, Ropert T. A question of classification. Science, N. S., vol. iv, 1896, pp. 918-920.
Marsu, O. C. The dinosaurs of North America. Sixteenth Ann. Rept. U. S. Geol. Surv., pt. i, 1896, pp. 133-414, pls. ii-Ixxxv.
The geology of Block Island. Am. Journ. Sci., 4th ser., vol. ii, 1896, pp. 295-298, 375-377.
54. Tuer LOWER CRETACEOUS DEPOSITS OF MARYLAND
The Jurassic formation on the Atlantic coast. Am. Journ. Sci., 4th ser., vol. ii, 1896, pp. 433-447.
Warp, Lester F. Some analogies in the Lower Cretaceous of Kurope and America.
Sixteenth Ann. Rept. U. S. Geol. Surv., pt. 2, 1896, pp. 463-542, pls. xevii-cevii.
1897
CLARK, WILLIAM Buttock, and Bispins, ArtHuR. The stratigraphy of the Potomac group in Maryland.
Journ. Geol., vol. v, 1897, pp. 479-506.
Warp, Luster F. Descriptions of the species of Cycadeoidea or fossil cycadean trunks, thus far discovered in the iron-ore belt, Potomac forma- tion, of Maryland.
Proc. Biol. Soc. Wash., vol. xi, 1897, pp. 1-17.
Professor Fontaine and Doctor Newberry-on the age of the Potomac formation. Science, N. S., vol. v, 1897, pp. 411-423. 1898 KNowLton, Frank Hatt. A Catalogue of the Cretaceous and Ter-
tiary plants of North America. U. S. Geological Survey, Bulletin 152, 8°, 247 pp., 1898.
1900
McGzr, W J. [The Sixteenth Street Section at Washington, D. C.] Science, N. S., vol. xii, 1900, pp. 990-991.
1902
Berry, Epwarp W. Notes on Sassafras. Bot. Gaz., vol. xxxiv, 1902, pp. 426-450.
BonsteEL, J. A. Soil Survey of Prince George’s county, Md.
Field Oper. Bureau Soils, 1901, U. S. Dept. Agri., Third Rept. Bureau Soils, 1902, pp. 173-210, pls. xxi-xxv, with map.
Dorsey, C. W., and BonstrseL, J. A. The Soils of Cecil county. Md. Geol. Surv., Cecil County, 1902, pp. 227-248, pls. xx-xxii, with map.
CuaRK, W. B., and Bippins, A. Geology of the Potomac group in the
middle Atlantic slope. Bull. Geol. Soe. Am., vol. xiii, 1902, pp. 187-214, pls. xxii-xxviii.
MARYLAND GEOLOGICAL SuRVEY
or Ot
Rises, H. Report on the Clays of Maryland. Md. Geol. Surv., vol. iv, 1902, pp. 205-505, pls. xix-lxix.
SHATTUCK, G. B. The Geology of the Coastal Plain Formations. Md. Geol. Surv. Cecil County, 1902, with geological map, pp. 149-194, figs. 8-11, pls. xii-xvi.
1903
Berry, Epwarp W. Aralia in American Paleobotany. Bot. Gaz., vol. xxxvi, 1903, pp. 421-428.
The American Species referred to Thinnfeldia. Bull. Torrey Bot. Club, vol. xxx, 1903, pp. 438-445.
1905 Bipsins, ARTHUR. Stratigraphical position and General Nature of
the Maryland Cycads. In. Ward, Mon. U.S. Geol. Surv., vol. xlviii, 1905, pp. 411-415.
1906 Cuark, Wm. Buttock, and MatHEews, Epwarp B. Report on the Physical Features of Maryland (with map).
Maryland Geol. Survey, Special Publication, vol. vi, pt. i, Baltimore, 1906.
Mitier, Benzamin LeRoy. Dover Folio. Explanatory Sheets. U. S. Geol. Survey, Geol. Atlas, folio No. 137, Washington, 1906.
Warp, Lester F. Status of the Mesozoic floras of the United States. Second paper, by Lester F. Ward, with the collaboration of Wm. M. Fontaine, Arthur Bibbins, and G. R. Wieland. Washington, Gov’t print.
off. (1905), 1906.
2v. exix pl. (incl. maps) 30% x 23 cm. (U.S. Geological Survey, Mono- graphs, vol. xlviii).
Contents.—pt. i. Text.—pt. ii. Plates.
1907 Bipsins, ARTHUR BaRNEVELT. Additional Evidence of Tropical Cli- mate on the Middle Atlantic Coast during the Lower Cretaceous. (Abstract) Science (N. S.), vol. xxv, 1907, pp. 297, 298. SHatruck, Grorce BurBANK; MILLER, BengyAmMIN LeRoy, and Brs-
BINS, ARTHUR. Patuxent Folio. Explanatory Sheets. U. S. Geol. Survey, Geol. Atlas, folio No. 152, Washington, 1907.
56 Tur Lower CRETACEOUS DEPosITs oF. MARYLAND
1910 Berry, Epwarp W. A Revision of the Fossil Plants of the genera Acrostichopteris, Tzniopteris, Nilsonia, and Sapindopsis from the Po-
tomac Group. Proc. U. S. Natl. Mus., vol. xxxviii, 1910, pp. 625-644.
A Revision of the ‘Fossil Plants of the genus Nageiopsis of Fontaine. Proc. U. S. Natl. Mus., vol. xxxviii, 1910, pp. 185-195, tf. 1, 2.
The epidermal characters of Frenelopsis ramosissima. Bot. Gazette, vol. 1, 1910, pp. 305-309, tf. 1, 2.
Geologic relations of the Cretaceous Floras of Virginia and North Carolina.
Bull. Geol. Soc. Amer., vol. xx, 1910, pp. 655-659.
Crark, Wm. Buttock. Results of a recent investigation of the coastal plain formations in the area between Massachusetts and North Carolina.
Bull. Geol. Soc. Amer., vol. xx, 1908, pp. 646-654.
Hill
Berry, Epwarp W. A Lower Cretaceous species of Schizeeaceze from eastern North America.
Annals of Botany, vol. xxv, 1911, pp. 193-198, tf. 1, pl. xii.
A revision of several genera of gymnospermous plants from the Potomac Group in Maryland and Virginia. Proc. U. S. Natl. Mus., vol. xl, 1911, pp. 289-318.
A revision of the fossil ferns from the Potomac Group which
have been referred to the genera Cladophlebis and Thyrsopteris. Proc. U. S. Natl. Mus., vol. xli, 1911, pp. 307-332.
STRATIGRAPHIC AND PALEONTOLOGIC CHARACTERISTICS
The Lower Cretaceous deposits of Maryland and adjacent areas have long been studied by many independent workers who have approached the problem from nearly as many different points of view. This fact, together with the proverbially complicated stratigraphy, has given rise to a highly varied taxonomy which is set forth in the previous chapter and the accompanying comparative taxonomic table.
MARYLAND GEOLOGICAL SURVEY 57
The Lower Cretaceous deposits are more highly differentiated in Mary- land than elsewhere along the Atlantic border, as is seen in both their lithologic and paleontologic diversity. The several formations present certain common features which need to be taken into considera- tion in any discussion of the strata.
The deposits, which are largely sands and clays of varying strati- graphic and lithologic characteristics, are, for the most part, uncon- solidated, although certain marked exceptions to this are to be seen in the locally developed sandstone beds in the lower part of the series. The deposits in general dip at progressively lower angles in passing upward in the series, although the Arundel formation affords some striking exceptions to this general rule. Again, the deposits thicken down the dip within the limits of the area of outcrop, although they apparently thin farther to the seaward, as shown by the well borings in which Lower Cretaceous strata are encountered. The stratigraphic re- lations show that after the deposition of the Patuxent and Arundel for- mations they were gradually transgressed toward the northward by the Patapsco formation before the close of Lower Cretaceous time. A study of the organic remains reveals a gradual progress in the types of plant life from the Patuxent through the Arundel and Patapsco, especially in the gradual advent of dicotyledonous types of plant life. These various features will be fully discussed in the descriptions of the several for- mations.
Tue Potomac GRouP
The Potomac Group, originally named by McGee for the deposits thus characterized in this report, was divided by Clark and Bibbins into the Patuxent, Arundel, and Patapsco formations, although they and others included within the Potomac certain higher deposits of somewhat sim- ilar character (Raritan formation) which are now recognized as of Upper Cretaceous age. A sufficient lithologic and paleontologic differ- ence occurs in these higher deposits to warrant the restriction of the term Potomac to those formations characteristic of the Potomac River region where they were first described by McGee under the name of the “ Potomac formation.”
58 Tue Lower CRETACEOUS DEPosITs oF MARYLAND
THE PATUXENT FORMATION
Name AND SynonyMy.—The Patuxent formation was so designated from the Patuxent River in Maryland, in the drainage basin of which its deposits were first recognized as an independent formation and named by Clark and Bibbins." It is in part the “feldspathic sandstone” of Rogers, the “lower oolite” of Tyson, and the “ Fredericksburg” or ~ “lower sandstone member” of Fontaine and McGee. It includes most of the “ James River” and a part of the “ Rappahannock” and “ Aquia Creek series” of Ward, and also a part of the “ Baltimorean ” of Uhler.
AREAL DistripuTion.—The Patuxent formation extends across the State in an irregular and at times interrupted belt, some 5 or 6 miles in average width, from the Delaware line through Elkton, Baltimore, and Laurel to the city of Washington. It forms generally the landward border of the Coastal Plain, although its outcrop is in places buried be- neath later deposits while seaward its surface continuity is interrupted by the principal water-ways, such as the Susquehanna, Gunpowder, Pa- tapsco, and Potomac rivers.
Outliers are found on the erystalline rocks to the west of the main body of the deposits, the two most conspicuous being the outliers at Catonsville and Lutherville. The former occupies one of the highest levels containing Coastal Plain deposits while the latter is found in a limestone valley a hundred feet lower than similar beds not far to the southeastward.
The Patuxent deposits in the Fall-line zone afford a very broken relief in the vicinity of the stream channels. The exposed hillocks of Patuxent materials with their slight cover of vegetation often suggest a bad land topography. Patuxent deposits have been observed in Maryland from over 400 feet in elevation near Catonsville to below 400 feet in a well at Indian Head.
LirHoLogic CHARAcTER.—The materials constituting the Patuxent formation are on the whole arenaceous, although argillaceous elements likewise appear. The sands, which are predominantly cross-bedded, are
1 Jour. Geol., vol. v, p. 481, 1897.
MARYLAND GEOLOGICAL SURVEY 59
sharp and the gravel mostly subangular, and not as well rounded as that of the overlying Pleistocene. The sand and gravel often contain a cou- siderable admixture of kaolinized feldspar, producing what is known as arkose. To the indurated derivative Rogers gave the name “ feldspathic sandstone.” Extensive deposits of rather fine and even-grained sandy gravel occur near the base of the formation, notably in the valley of Herring Run, at Roland Park, and near Cub Hill in Baltimore County, where the materials have been employed to a greater or less extent as road metal and for concrete. The basal gravels are often coarse and cobbly, and adjacent to the crystalline floor are often indurated by hydrous iron oxide to a resistant ferruginous conglomerate. Toward the northward, in the vicinity of Perry Hall, Baltimore County, and in the Broad Creek valley in Cecil County, the basal conglomerate is of light color and is filled with angular fragments of quartz. Buff-colored sands of fine-grained texture with some admixture of brownish loam are common in the vicinity of Baltimore City, where they have been exten- sively employed as building sands. White glass sands somewhat arkosic have been worked to some extent at Westport in Baltimore County. The Patuxent sands are often indurated by hydrous oxide of iron and take on very irregular and fantastic shapes, including hollow cylinders, in- tricately corrugated plates and spherical and ellipsoidal gourds having the local names of “sand bullets,” “sand clams,” ete. These indurated phases are well developed at the Homestead sand pits near the old Pat- terson mansion in Baltimore City. A ferruginous oolite is occasionally found, especially in the vicinity of Washington, this phase recalling Tyson’s term “ Lower Oolite” for the deposit. The Patuxent sands are very varied in color, the most distinctive being purple, which is perhaps due to slight traces of manganese in the deposits.
The clays of the Patuxent formation are much less important than the sands, with which they occur either as pellets or larger masses in the arkosic materials or in interbedded streaks and lenses which at times are of considerable extent. They commonly consist of kaolinized material of greater or less purity, and locally known as “ Fuller’s earth.” The clays are prevailingly white, but are at times of various delicate
60 THE LOWER CRETACEOUS DEPOSITS OF MARYLAND
shades of red, yellow, brown, maroon, and lavender, in piebald tints and patterns of great beauty. ‘The purple coloring is very characteristic. Extensive lenses of these brilliantly colored clays occur in the eastern part of the city of Baltimore, where they constitute an important re- source for the brick industry. They were penetrated to a depth of 40 feet in the excavations for the new outfall sewer for Baltimore City without reaching their base, and were so resistant as to require the almost constant use of the mattox. At Bayview these same clays were so resistant as to require blasting. The clays are at times drab or black in color, from the admixture of carbonaceous matter. Very definite beds of lignite occur at some points, notably near Jessups and at Clifton Park, at both of which points the lignite has been employed to some extent as a fuel, although the beds are rarely more than a foot in thickness and are of small horizontal extent. Lignitized twigs, limbs, and trunks always strongly compressed as well as fossil leaves are not uncommon in these deposits. Lignitized stumps have occasionally been found in erect positions. The comminuted carbonaceous matter is at times so abundant in the clays as to produce an earthy lignite of dead- black color. A deposit of this character filled with lignitized stems occurs in the valley of Broad Creek, Cecil County overlying the basal conglomerate before mentioned. Occasionally the drab or lignitized clays carry carbonate of iron as at Gaither’s Dam in Stony Run, Anne Arundel County, but the deposits are of small economic importance.
Deposits of red and yellow hydrous oxide of iron are at times found in sufficient extent to possess economic value as pigments. Such deposits frequently occur at the top of sand beds which are overlaid by drab clays, as at the base of the terra cotta clays at Federal Hill.
STRIKE, Dip, AND THICKNESS.—The strike of the Patuxent formation in Maryland is in a general northeast-southwest direction, becoming more nearly north and south as the valley of the Potomac is reached, to the south of which, in Virginia, the strike is north and south.
The dip of the beds is to the southeast but is variable in amount, espe- cially in proximity to the Fall-line, where in places it largely exceeds the dip of the main body of the deposits farther eastward. The dip to the
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE
Fic. I.—VIEW SHOWING ERODED UPPER SURFACE OF THE PATUXENT OVERLAIN BY SUNDERLAND DEPOSITS, BELT LINE CUT NEAR CHARLES STREET, BALTIMORE CITY.
Fic. 2.—VIEW SHOWING PATUXENT-ARUNDEL CONTACT, SOUTH SHORE OF SPRING GARDENS, THE PROBABLE LOCALITY WHERE TYSON COLLECTED THE HISTORIC JOHNS HOPKINS CYCAD STUMP, BALTIMORE COUNTY.
MARYLAND GEOLOGICAL SURVEY 61
east of the Fall-line varies from 50 to 90 feet in the mile, the average being about 60 feet in the mile. The rate of dips in feet per mile at various points is:
FEET FEET FEET Burtonsville ....... 9 letra TEEN Boe en abc 66 Battle Swamp ..... 73 UIC se euciev sleet ses Gbi—oreleys). 32 wack ee see UO DHT OO OLS meee nice sare 100 Ilehester Hill ..... 68 North of Joppa...60-80 Bay View ......... 90 OA eects els 6 ors ele ee 200 seA Dine donueeeeee LOO) sHeree Hille wessetes 80 Catonsville” .:.....-< 114 Harford Furnace... 70 Cherry Hill........ 60 House of Refuge.... 75. Carsins ...<.2-..... 100) Barksdale 25 .- sees 45 Baltimore ........ 80-90 Aberdeen ......... UO SET GLAy Se Eli lever.ie scree 50 PROWSOM)...n5 06 ore acs 669 VATCIiniOs ieee. teclerers AN) Uo ET Bass gogon 50 (Gui) ISG See oaces 5S: WiCDStETM oarnscre cave orc 100 Chestnut Hill, Del.. 50
The altitude of the Patuxent beds in the Lutherville area previously mentioned is anomalous, for besides lying at a lower level than the de- posits farther to the seaward the dip is slightly to the northwestward.
From the above facts it is apparent that the deposits near the Fall- line have been subjected to greater deformation than the beds farther eastward, still in no instance is there any certain evidence of actual faulting along this line, although the high angle of dip at Relay, the elevated position of the beds at Catonsville, and the abnormal altitude of the strata at Lutherville, all point to unusual structural conditions that may find their explanation in the faulting of the strata.
The maximum thickness of the Patuxent formation in Maryland is not less than 350 feet and may considerably exceed that amount. In the well boring at Indian Head it has been penetrated for a thickness of 353 feet without reaching the crystalline floor. In northern Virginia, at Alexandria, the brewery well shows 380 feet of Patuxent materials. Toward the landward margin of the Patuxent formation less thicknesses are found, the deposits frequently not exceeding 150 to 200 feet. A similar thinning of the formation occurs seaward, as shown by the deeper well borings in eastern Maryland and Virginia.
STRATIGRAPHIC AND STRUCTURAL RELATIONS.—The Patuxent forma- tion, as the basal formation of the Coastal Plain, rests directly on the crystalline rocks of the tilted and submerged margin of the Piedmont Plateau. This surface more or less eroded and trenched before the
62 THe Lower CRETACEOUS DEPOSITS OF MARYLAND
deposition of Patuxent sediments has been elsewhere described as the Weverton peneplain. Monadnocks rise from its surface, as at Grays Hill, now surrounded by Potomac deposits. These underlying rocks in Maryland consist, as far as known, only of crystalline rocks of early Paleozoic and pre-Paleozoic age, although both farther north and south the Newark formation of Triassic age here and there reaches to the Coastal Plain border. The slope of this ancient surface which has been regarded as of late Jurassic or early Cretaceous age, is quite uniformly about 75 feet in the mile towards the southeast, although local differences occur due to the irregularities of the surface previously described.
The Patuxent formation is sometimes irregularly overlain uncon- formably in Maryland by the Arundel formation, which apparently occu- pies post-Patuxent drainage lines that had been warped before the deposition of the Arundel sediments. Covering both formations un- conformably, and in the absence of the Arundel resting directly on the Patuxent formation, is the Patapsco formation, which in Virginia, where the Arundel formation is absent everywhere, comes in contact with the Patuxent formation. In the absence of both of these formations of the Potomac Group later formations of Upper Cretaceous, Tertiary and Qua- ternary age are found overlying the Patuxent deposits unconformably.
The internal structure and stratigraphy of the Patuxent formation is at times very complex, more so than that of any of the other Coastal Plain formations. Contemporaneous erosion planes, very coarse and steeply inclined cross-bedding and alternations of extremely dissimilar and sharply demarked beds and lenses in irregular attitudes, although not the rule, are not at all uncommon.
At times small folds occur in the beds in contact with the crystalline rocks which are apparently due to local expansions in the latter, as the result of their hydration. An interesting fold of this character is seen in the pits of the Maryland Clay Company at Northeast, Cecil County, as the result of the kaolinization of the feldspathic rocks.
To what extent the beds have been subjected to larger structural changes cannot be readily determined. The abnormalities in dip in the vicinity of the Fall-line have been already referred to, and the possibility
MARYLAND GEOLOGICAL SURVEY 63
of faulting suggested, although no definite evidence on that point exists. It is evident, however, that a warping of the beds occurs whether with or without dislocation of the strata. The main body of the deposits may well have been subjected to deformation in the many differential move- ments which are known to have taken place in the Coastal Plain in post- Patuxent time. Furthermore, some of the marked changes in dip in the later formations, as notably in the Magothy formation along the line of the Chesapeake and Delaware Canal, suggest the possibility of actual folding of the underlying formations. |
OrcGANIc Remains.—Although the Patuxent deposits are in general unfossiliferous because of their coarse character, nevertheless a consider- able flora has been collected from clay balls and lenses and the more argillaceous sands, especially from beds of this age in the Rappahannock and James river valleys in Virginia.
This flora includes a large element made up of survivors from the older Mesozoic, and is rich in species and individuals referred to the fern genera Cladophlebis and Onychiopsis. Other genera of ferns, such as Acrostichopteris, Schizeopsis, Scleropterts, Tenopteris, Ruffordia, ete., are less common. A variety of cycad remains testifies to the abundance of this type of plant, represented for the most part in the Maryland area by the silicified trunks of Cycadeoidea, of which several different species are known. Cycad fronds, less common in Maryland, are abundant in the more argillaceous deposits of this age in Virginia, and include a variety of genera such as Nilsonia, Podozanutes, Zamites, Williamsoma, Ctenopteris, Clenopsis, Ctenis, etc. Perhaps the most striking of these remains are the large forms of Nilsonia and the splendid fronds of Dioonites.
Among the gymnosperms are species of Sphenolepsis, Baiera, Brachy- phyllum, Frenelopsis, Nageiopsis, Arthrotaxopsis, Sequoia, and Cephalo- taxopsis. These are for the most part genera that range from the late Triassic to the Upper Cretaceous. They are abundant in the Patuxent and represent families which in the modern flora are largely natives of
other continents. 5
64. THe Lower CRETACEOUS Deposits oF MARYLAND
Supposed, but altogether doubtful, angiosperms, the most ancient known, are represented by the genera Rogersia, Proteephyllum, and Ficophyllum, which perhaps should be considered the remains of foliage of the gymnospermous order Gnetales.
The known fauna of the Patuxent is represented by a single fish found in the James River area, but it is extremely probable that the rich dinosaurian fauna of the overlying and closely related Arundel forma- tion flourished during Patuxent time, since in the west the representa- tives of this fauna occur in the Morrison formation conformably below the Kootanie formation, which carries the representatives of the Patux-
ent flora.
THE ARUNDEL FORMATION
Name anD SynonymMy.—The Arundel formation was named from Anne Arundel County, Maryland, where the deposits of this formation were first recognized as a distinct unit by Clark and Bibbins.” It is the lower portion of the “upper oolite,” or “ Iron-Ore Clays” of Tyson, a part of the “ Variegated Clays” of Fontaine, and McGee, and of the “ Baltimorean ” of Uhler, and is the equivalent of the “ Iron-Ore series ” of Ward.
AREAL DistriputTion.—The Arundel formation outcrops in an irreg- ular and partially interrupted belt that extends from the head of Bush River, in Harford County, to Washington, D. C. This belt adjoins that of the Patuxent formation to the west, and reaches its maximum width of 7 miles in the. northern portion of Prince George’s County, its usual width being from 3 to 5 miles. Where the formation is not overlain by later deposits it generally forms broad dome-shaped hills. The observed vertical range of the Arundel deposits is from 300 feet above tide to the landward to 368 feet below to the seaward.
LitHoLtogic CHaracters.—The Arundel formation consists typically of drab, more or less lignitic clays, carrying nodules, geodes, flakes, and
ledges of earthy iron carbonate or siderite. The nodules or geodes. are
* Loe. cit., p. 485.
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE V.
Fic. I.—VIEW SHOWING INDURATED LEDGES IN THE PATUXENT FORMATION, W STREET NEAR I2TH STREET, WASHINGTON, D. C.
Fic. 2.—VIEW SHOWING FLOODED IRON MINE IN THE ARUNDEL FORMATION NEAR MUIRKIRK.
MARYLAND GEOLOGICAL SURVEY 65
often septarian, and their cavities are commonly lined by brown velvety masses of siderite crystals, which change to brown hematite on exposure to the air. The materials of the Arundel formation are so strikingly homogeneous, as compared with those of the underlying Patuxent and overlying Patapsco, that its deposits have served as a datum plane for Potomac stratigraphy in Maryland, and the iron produced is prized for its high tensile strength.
The clays are commonly free from grit, but are at times sandy, and to the landward the sand may predominate, as in the vicinity of Washing- ton. The clays are not infrequently pyritous and gypseous, both minerals commonly occurring in druses. The gypsum druses frequently line the septarian nodules but also occur free in the clays, as at Spring Gardens. The clays are in general unctuous or “ fat,’ and are an important resource for brick, terra cotta, and pottery manufacture. They have been worked for these purposes at several points, but will undoubtedly be much more extensively employed in the future.
The siderite deposits known locally as “ oolite ore ”
are changed com- monly at the surface, and in the clays poor in carbon to greater depths into hydrous oxide of iron or hmonite, known locally as “ brown ore.” These ores have been mined since early Colonial days, one furnace at Muirkirk being still in operation.
The lignitic element in the deposits, which gives to the clays their characteristic drab color, at times becomes so pronounced as to form well-defined lignite beds, which have been locally used as fuel, as at Soper Hall Hill, Anne Arundel County. The lignite is at times finely seattered through the clays, at other times trunks, limbs, twigs, and leaves are found well preserved, the stumps in some instances being found in erect position with their roots intact as they grew. At times the woody fibre may be partly replaced by siderite or by pyrite, as at Reynolds’ iron mine at Hanover.
STRIKE, Dip aND THIcKNESS.—The strike of the Arundel formation
is essentially parallel to that of the Patuxent toward the north, being about northeast to southwest and gradually becoming more nearly north and south as southern Maryland is reached.
66 THe Lower CRETACEOUS DEPosITs oF MARYLAND
The dip of the beds is to the southeast, and is in general at the rate of about 50 feet in the mile. It is greater in the Fall-line zone, as shown in the Putty Hill, Carney, and Camp Chapel areas, and is less to the eastward.
The observed thickness of the Arundel formation varies from a few feet to about 100 feet or perhaps 125 feet in the middle of the belt in central Maryland. It apparently thins seaward, as shown by the well ‘boring at Sparrows Point. |
STRATIGRAPHIC AND STRUCTURAL RELATIONS.—The Arundel forma- tion overlies the Patuxent formation unconformably, occupying what appear to be old drainage lines therein, but extending beyond these to the seaward where it spreads into a more or less continuous sheet. The formation rarely comes in contact with the crystalline rocks, but a few instances are known, as at one locality north of Relay and in the Camp Chapel area.
The deposits are unconformably overlain by the Patapsco formation, or in the absence of the latter by the later Tertiary and Quaternary formations.
The internal stratigraphic and structural features are relatively simple, the strata consisting for the most part of widely extended beds or lenses of clay with included beds of lignite and iron ore. Some cross-bedding is found in the basal beds landward but it is unusual. The strata give evidence of deformation similar to the Patuxent beds in the Fall-line zone, and are likewise affected by the general warping of the underlying Patuxent previously described.
Organic Remarns.—Both animal ‘and plant remains occur in the Arundel, its manner of deposition favoring the preservation of both.
The Arundel fauna represents, so far as known, three orders: Dino- sauria, Crocodilia, and Testudinata.
The dinosaurs represent all of the sub-orders, including two of the heavier, megalosaurian carnivores, Allosawrus and Creosaurus, and one of the lighter, compsognathus type, Celurus. The quadrupedal Sau- ropoda are represented by at least one genus, possibly two, Pleurocelus and Astrodon, including two or three species in all, while of the Orthop-
MARYLAND GEOLOGICAL SURVEY 67
oda there are two, one the unarmored Dryosaurus, the other, Priconodon, evidently belonging to the armored group or Stegosauria.
The dinosaurs show none of the remarkable over-specialization of the later types, but, on the contrary, represent the order at the crest of the evolutionary wave, before the signs of decadence set in. Unfortunately, owing to an almost utter dearth of terrestrial Jurassic deposits, nothing is known of dinosaurian evolution in America from Newark time until we come to the horizon under consideration. In Europe the record, though still meagre, is more complete; but it represents in every instance more primitive types than those of the Potomac and the Morrison.
The flora is of the same type as that of the Patuxent, most of the genera and a large number of the species of the latter having been found in the Arundel and where unknown the presumption is strong that they still existed in nearby areas, since the known Arundel flora contains no new or younger elements than does the Patuxent, and indi- cates that the marked change in the flora of the Potomac occurred during the time interval represented by the unconformity between the Arundel and the overlying Patapsco formation.
The Arundel formation also contains poorly preserved representatives of fresh-water molluscs.
THE PATAPSCO FORMATION
NAME AND Synonymy.—-The Patapsco formation was named by Clark and Bibbins* from the Patapsco River in Maryland, in the drain- age basin of which stream the deposits are well exposed and were first studied as an independent formation. It was included by Rogers in his “Upper Secondary ” or “ Jurasso-Cretaceous ”; by Tyson together with the preceding formation in his “ Upper odlite.” It was with the Arundel
“ varicolored ” clay member. The
included by McGee in his upper or formation was not differentiated either by Marsh, Fontaine, Ward, or Darton in their Potomac. It corresponds in part to what Fontaine
termed the Baltimore beds, and includes Ward’s Mt. Vernon series and
1Loec. cit., p. 489.
68 THE Lower CrEeTAceous Deposits of MARYLAND
part of his Aquia Creek series as well as what he also called the Brooke beds. |
Arvat Disrrisution.—The Patapsco formation outcrops in Maryland in a belt of varying width extending from the Delaware line southwest- ward to the District of Columbia to the east of the preceding formation. To the south of Washington it is found along the valley of the Potomac to below Mattawoman Creek. From the Delaware line to the District the belt has a width of about 5 miles, south of which it narrows appre- ciably until it finally disappears in Charles County, aithough continued on the west bank of the Potomac in Virginia. It is a much more con- tinuous belt than the preceding Arundel formation.
Outliers are found resting on the Patuxent formation. The surface is rolling, resistant caps frequently occurring as the result of the fer- ruginous crusts which are often developed. The Patapsco deposits have been found all the way from hills 300 feet and more in elevation to a depth of about the same amount in well borings.
LirHoLtocic CHaractEers.—The Patapsco formation consists of sands and clays which differ, however, from those of the Patuxent formation in the predominance of the argillaceous elements, especially the varie- gated clays. The arkosic sands and gravels are much less common than in the Patuxent formation. They are more common toward the southern part of the area, where they at times become indurated, forming a part of the well-known “ Virginia freestone” of the Aquia Creek area. A band of pebbles frequently marks the base of the formation, as in the Hanover region. A bed of broken and redeposited ironstone crusts may take the place of the pebbles, as near Hawkins Point on the Patapsco River. |
The most characteristic materials are the highly colored and varie- gated clays with their red, drab, and chocolate colors. The clays often grade into or are interbedded with sandy clays, sands, and gravelly sands. They are at times lignitic, a typical illustration being the lignitic sandy clay at Fort Foote. Pellets of fossil resin at times occur with the
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE VI.
etl
Fic. I.—VIEW SHOWING THE PATUXENT-ARUNDEL CONTACT IN BELT LINE CUT NEAR THE EASTERN BOUNDARY OF BALTIMORE CITY.
Fic. 2.—VIEW SHOWING EROSION OF OLD IRON MINE IN THE ARUNDEL FORMATION, SCHOOLHOUSE HILL, BALTIMORE COUNTY.
MARYLAND GEOLOGICAL SuRVEY 69
lignites. Small deposits of pyrite are also found in the same beds. The variegated clays which commonly exhibit a great variety of exception- ally rich and delicate tints in irregular patterns often grade _hori- zontally into massive drab and black clays, which are often lignitic and occasionally iron- or leaf-bearing. The sand sometimes contains pellets or balls of white clay. They are frequently cross-bedded, although not as strongly so as the sands in the Patuxent formation. Red ochre, known as “paint rock” or “paint stone,” occurs near the base and summit, and sometimes within the formation, while flakes of sandy and ocherous limonite with botryoidal inferior surfaces are not uncommon at certain horizons. The variegated clays often contain small pieces of flattened limonite quite uniform in size. The drab and chocolate-colored clays have been worked at some points for iron carbonate in the Middle River region, but the amount of ironstone is small compared with that in the Arundel formation.
STRIKE, Dip, anD THIckNEss.—The strike of the Patapsco formation is essentially the same as that of the two preceding formations. The direction changes slightly due to the structural features involved in the central portion of the area by which the Patapsco formation gradually - transgresses the earlier formations, both toward the north and toward the south, which slightly affects the direction of the strike in the same areas.
The dip is to the eastward at the rate of about 40 feet in the mile, although it is somewhat increased within the Fall-line zone. The thick- ness of the Patapsco formation is somewhat in excess of 200 feet, the maximum thickness being observed in a well boring at Bowie, near the Raritan-Patapsco contact, where a thickness of 260 feet was found. The wells at Sparrows Point show a thickness of 204 feet, but it is pos- sible that the upper beds had been eroded before the Pleistocene deposits were laid down. At Red Hill, Cecil County, a thickness of 130 feet has been observed, while at Grays Hill, in the same county, it reaches 100 feet.
70 THe Lower Creracreous DrEposits or MARYLAND
STRATIGRAPHIC AND STRUCTURAL RELATIONS.—The Patapsco forma- tion rests unconformably on the underlying formations and at the 340- foot hill at Relay transgresses them and rests on the crystalline rocks. Toward the north the Patapsco deposits gradually transgress the underlying formation, and in Delaware and Pennsylvania rest di- rectly on the crystalline rocks at a number of points. Monadnocks of crystalline rock penetrate the Potomac formations at several points in northeastern Maryland and the adjoining portion of Delaware.
The Patapsco formation was much eroded prior to the deposition of the Raritan, so that marked irregularities are found in the line of con- tact which represent rather pronounced inequalities in the upper surface of the Patapsco. In general the line was well defined, and at some points is marked by a line of broken and redeposited iron crusts. In the ab- sence of the Raritan, which gradually thins out towards the south, the Patapsco formation is overlain unconformably by later Cretaceous or Eocene deposits, while in the absence of both later Cretaceous and Ter- tiary deposits, the Patapsco formation is often overlain unconformably by Pleistocene deposits.
The internal stratigraphy and structure of the Patapsco formation is somewhat complex, on account of the great difference in the character of the materials, ranging, as they do, from very plastic and highly variegated clays to coarse sands, the latter occurring in lenses and beds which at times considerably complicate the stratigraphy, although they are not sufficiently continuous to make it possible to subdivide the Patapsco into members of more than local importance. Such local lithologic terms have been employed by others, but the very circumscribed limits of these beds render their use very problematical.
Some warping of the beds evidently occurs along the Fall-line, as shown by the differences in dip, and it is quite possible that actual faults occur, although on account of this continuity of the strata and their frequent cover of later deposits it is impossible to determine this
point definitely. As already pointed out, the marked changes in dip
MARYLAND GEOLOGICAL SURVEY V1
seen in some of the later formations, and particularly the Magothy for- mation along the line of the Chesapeake and Delaware Canal, suggest the possibility of actual folding in the Patapsco and earlier formations.
Organic Remains.—The Patapsco deposits have yielded a few speci- mens of poorly preserved unios and an extensive flora, including repre- sentatives of the Pteridophyta, Cycadophyte, Gymnosperme, and Angiosperme. The ferns, cycads, and conifers represent for the most part the dwindling remnants of the Patuxent-Arundel flora, some species being common to all three formations and the genera being largely identical. The fern genera Scleropteris, Schizwopsis and Tem- opterts have disappeared, but Ruffordia, Cladophlebis, and Onychiopsis are stillcommon. Petrified remains of a species of Tempskya and im- pressions of fronds of a peculiar new genus of ferns, Knowltonella, are highly characteristic of this formation. Among the-cycads Podozamites and Zamites are represented, but the genera Nilsonia, Dioonites, Clenss, Ctenopteris, and Ctenopsis have disappeared. Silicified trunks of Cyca- deoidea have been found in the Patapsco, but it is questionable if they have not been reworked from the older formations.
Among the gymnosperms Laricopsis, Baiera, Cephalotaxopsis, and Arthrotaxopsis are no longer represented. Species of Widdringtonites and Pinus are new and characteristic, while the genera Sequoia, Spheno- lepis, Brachyphyllum, and Nageiopsis are still present.
The marked distinctness and more modern aspect of the Patapsco flora is due, however, to the abundance of Dicotyledone, which fore- shadow and were undoubtedly for the most part ancestral to the Dicotyled- one of the Upper Cretaceous Raritan formation.
The more characteristic of these are the various species of Aralia- ephyllum, Sterculia, Cissites, Celastrophyllum, Populophyllum, etc. The compound leaves of Sapindopsis are one of the most striking dicotyledo- nous elements present. Three species are known and all are strictly
confined to this horizon.
We THE Lower CRETACEOUS DEPosITS oF MARYLAND
LOCAL SECTIONS
I. Section at “ Red Hill,” along the west slope of Gray’s Hill, Cecil County, beginning at 200 feet above tide.
Feet. Cretaceous. Coarse reddish sand and evenly-bedded dark brown Raritan ... sandstone ledge... & fic se Secrets eat eee repre te Os Yellow and buff sand and corrugated iron stone....... 10 (Tough white clay reddish in places................... a
Patapsco ....Massive variegated red and drab clay, the latter - slightly lignitic and containing obscure leaf im- pressions. Lenses of white, water-bearing sand near
DAS Oo otce Aas Pee rer teee ste el kee Sas eee ee 130 Patuxent ...Sand, not exposed at surface, to tide level............. 43 TOGA icc: sea eatiee. ac Saspapocanene aheaaie, Saran A cee cy oe 200
II. Shannon Hill near Northeast, Cecil County.
Pleistocene or Feet. Recent 622s. hoam ‘andsred scla yon e seer se I ee eee 5-10 Cretaceous. ‘ Raritan ....Dense plastic chocolate colored clay with flakes of iron carbonate carrying leaf impressions................ 10 hight colored: sande eatin cnet ster 2 oe ee ee ee eee 8 Sandy, chocolate colored clay. sone eee 10 Drab and light colored clay and sand grading into WESES MNEGMND OR ~ sng ce ciarte can stecee eared os ate eed Haale dere Patapsco ..2 Chocolate clay, slightly lignitic....................-.- i Variezated=clay 2s25.. ent a. = CCG ASM TARE Mp Oe oe teeta 18 WEEE SAG eee ee is hoe tena eee REE Peed eee al Varlerated Clay. eoisc oun sa eto on tn Oe eae 35
Yellow and purple sand and ferruginous sandstone.... 5
IIl. Section of Baltimore and Ohio Railway cutting at Foy’s Hill, Cecil County, beginning 270 feet above tide.
Feet IRNGCEN ER eye coer JGravelly. loam= “wash? os soclse coche = bere eee 5 Cretaceous. MiNe WRITE SSAN GA. trun ea em eS tea ere ene 11 Brown loamy sand, more or less gravelly and arkosic ; LO Wards DASE: clerciisins afcless oi sye concern cates cree ion eens 12 Raritan ..-~4 White chinaware clay, more or less iron tinted, and varicolored, at times grading horizontally and ver- tically into micaceous sand and becoming gravelly and arkosic toward the base.............ecee00:% 10-20 Patapsco ....Very dense, richly variegated clay, to and below the ENC NGM Gago cHacdsagrm bloc soap gooscoSoscdeenre ~ 104+
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE Vil.
FIG. I.—VIEW SHOWING EROSION OF ARUNDEL CLAYS, HARTKE IRON MINE NEAR HANOVER, HOWARD COUNTY.
Fic. 2.—VIEW SHOWING REYNOLDS IRON MINE IN THE ARUNDEL FORMATION, I MILE SOUTH OF HANOVER, ANNE ARUNDEL COUNTY.
MARYLAND GEOLOGICAL SURVEY 13
IV. Well Section at Sparrows Point, Baltimore County, Well No. 4, beginning : 10 feet above tide.
Feet. Inches.
FREECONTU 6 wie veces ATUL GiLLET eters cute. chee eects Wrote evaehararelea ie cele 10 - Pleistocene. Medium: coarse: Duk Sandie. ..ncesies co cee ulcle. 12 Mealbaten. . Coarse light drab Sand. 03. ies cede de sne ce 53 Drab calcareous clay, with remains of marine
IMVETLEDLALES sacs ole reetceeecsve weenie td eis aust ere 20
Cretaceous. Ma Wachtecoloredeplastic claymnnceniss eaten ae wee 22 IMeiye COATSE #2 TaVielier. sete nano ote Ceasar 3 Whites. Sam GH Goats Serr ae ee Salas tect Oe 5 HIN OLST AVE] eve cures GeO hor ae eh betes 5 Hardibrown claves sa eie cates cor weioct ols deters 15 HEEDUNGPD UTE SATLG sro 'c.e cule te ee mer islets. <caseVecars hare wi 13
Fine white water-bearing sand................ 3 WieryCOarserSTravell ics. ee ee Cee ak 8
HMardesticky, tinerreduclayn.. ay. sisal 32
Patapsco ..+ Coarse water-bearing sand.................-- 12
Data from the neighboring coke oven well carries the section beyond this point. Begin- ning at 220 feet from surface, near base of the foregoing member.
JRO + GI EARIAR et ar iniatn tera et aaNet een a St = A ae NO Se 62 WAVED SS ATT Diss inet ons airs a yet ote fe cotleahe aces) een or hee 9 | Red CUA Rea sites orelneeae ahr Bosley Bek ronal ean orrenate reams 4 | Hard SeDIN letra cheater noes one eh over nen he romeo eR Newer cena 5 PROUT CO CLAY sei oisre SuctecatsiaeieXe ae eteysie ares ele aero 74 Arundel (?)4 “ Flint rock” (probably iron carbonate)...... 0 3% | Soft blue clay, iron nodules at one level...... 23 85% (Gyan SAIN easter tos 30s. Pore Meal a, w. hawaattote ce, aleveLeone ab ayeress 21 Ea MCHEL NE: INEPeMUGIAY soca ts. ss 2st oe dun sig x mante se ene 6 6 LUG TaSTT OWI veh fee eke hekeoe nase ches se, Sone here orerarche emai F(ab CGrystllimemnockssGramiterat. 4.08 ce. 55 pe meee oh oe cle ele wpe eimelee 495
V. WSection of Baltimore and Ohio Railway cutting east of Bay View Station, Baltimore County, beginning at 130 feet above tide.
Cretaceous. : ; Feet. Patapsco (?).Buff, ferruginous sands, often indurated and capping INGE SITE ODM ox ette: cure rages By aroys ac se eae See eickgeeel tre cea a eae chee ote 10-20 Arundel ....Drab stratified leaf-bearing clays, occupying a depres- sion in the surface of the Patuxent’............... 0-15 White and varicolored, more or less indurated, cross Patuxent . bedded sands and gravels, somewhat argillaceous and with lenses of sandy clay to the level of the railway ESTREC Kara ae casa ee sal gene oo Rea eore Saw sare Maoen ahie Oe crane leas tone ae ekeen Hats 5-20 FINO Ui tenn tes eps te ars a ah wearer haretey Dac oto es aieReT epee te aeee eee aN 53
1See list of species in Tables of Distribution.
74. THE LoWwER CRETACEOUS DEPosITs oF MARYLAND
VI. Section of Belt Line cut near Eastern boundary, Baltimore City, beginning 180 feet above tide.
Pleistocene. Feet. Sunderland .Brown more or less gravelly loam, at times with re- worked iron crusts. Occasional loose ferruginous sandstone masses at base..............02.0cceeeeee
Cretaceous. Patapsco ...Hard, irregularly bedded, buff sand with thin corru- gated plates of iron sandstone toward the eastward.. 0-15
Arundel ....Mostly massive dark red, yellow or mottled clay some- what sandy, locally wanting...................... 0-20
White and varicolored, often micaceous and cross bedded sand and sandy clay, with crusts and ledges Patuxent .. of sandy mammalary limonite near the top.......... Coarse white sandy micaceous gravel, locally indurated toward summit by hydrous iron oxide, exposed... .10-20
VII. Well section at “ Smith’s Distillery,” Baltimore.
Tyson published in 1860 a record of strata penetrated by this well on North- west harbor, which presents a typical Patuxent section. The well began at 10 feet above tide.
Feet
Recent: (528552. RUVERVIMUG: eer teres ot pcear ye aan eae Pe eS er aeeat capa 52 Cretaceous.
Sane eravelvand-boulders:.cm scene oe awe 6
Hard blue iclayimscvrs nc seins nen eters SE ee ee 9
FROG SCL ayer ak ich eters See eens OE eee ear ore eee 6
Patuxent sea Red ocher e)jekiel evieliellepe!= le \s\iel eile ivjlejiel/stie:iale\atiel(sliaja)'s) etteliee)\=| /sitcitel silel=|(s'gatieitic 5
WihiteSantd Bo cee. 0 Se ae ee ca orn eee eee 4
WATES Clays eeaeaseecsieee caer eae oe a ee aS Be
White sand and gravel, water-bearing................. 8
White sand, gravel and boulders, water-bearing....... ra
Crystallines! .3.c © GHEISS a oc cet eee shoth One Ae ee aoe ee ea 7
RCo or) Uncen ape Fa AM RON eR oe RA MEET tO Mh eta aalu AB a et 129
VIII. Well section at Torsch Packing Company, Chesapeake Wharf, Baltimore, beginning 10 feet above, tide.
Feet
SIG] Soe. ok: isvale alate caro aise ces tose har oe Nake PG oe eee ee 8
Recent ........ | ated ae ee Oe er Mat een Maal tah Opa tee ae ITE 7 Mudiwitheshellstandseraviel as eerieeee ene nee i
Cretaceous. UGG SOLA: Fad Ses res ae ale eee oe ee ae Cane eee rene or i ene cate 8 WWiENICGO: CLAY: sohaecee seus tose oe eee ee 15
Sandy “white: clay. bean ce eee enero Cee ally
Patuxent: >. 2\ Sand rock crack oo an ee ee eee ae 5 Impervious white clay. ssc eee ate ee Ree ore 15
Water-bearine white ssand. 2.225.050. 00.00e ven eoene See,
Hstimated to "hed rocks stic.e poise eee eink Fie 48
“ eed
Pe Se ee eee Oe
MARYLAND GEOLOGICAL SURVEY 15
IX. Section at Federal Hill, Baltimore, at Baltimore Terra Cotta Works, Covington and Ostend Streets and beginning about 70 feet above tide.
Feet. Inches. Cretaceous. Sandy clay, sand and ferruginous sandstone, with silicified wood and red clay laminae... Carbonaceous clay with flakes of white and LOM TMT TOM OTE srarcie: sey ents oct fo 'n evacate elatalel ate place ee 1 4 “Alum clay,’ “yellow horse clay,’ yellow ochre, and variegated clay, at times sandy and containing iron crusts and tubes........ 34 6 Bluish clay and potters clay with semi-erect Patapsco ...{ stumps and horizontal logs of lignite, im- pregnated with pyrite. Occasional fern im-
10
ol
DRESSIOMGSR crate ats. Sicin wue-e ose sueueve. oo Suara eive Somer cvels f 6 Darker blue slaty clay, without fossils........ 3 Gray slaty clay, with profusion of plant re- TUDE TTNS sami Meee eee cea ewan CRY alee ch enrahons ai el sites che alors ae ee SENIGK ANGIE Sig cata Bic Cle ORIOL oid on nis Bio ORT Z Indurated ferruginous layers................. % Wonmmencialvredtochnrer sense cee eee cee ee 3% TONS SANG SEONG! iccte lace co as otele ohsiete e's « Slelcve siete y AWA CAG ATO Met Antonia earls leotates conde choweteyausc ieee eesere 7 Fine white sand with white clay balls........ 4 Building sand and indurated gravel, near tide. 4 The well at the Torsch packing house carries Patuxent ..J this section downward (ailowing for dip) as follows: BVV iNT ESRC TAA rece ce) cvs relerece title cisieus eyeasue s slelisnecolaue © 15 ANTRNTEKGEOWUS Widow CEA oo guudsoccbodcdsse6s000 15 Save PO Clee shots soot io iaateuekcutl sis fo tokeve alla echo totelel scanete rete 5 Wynne) sian erAGIOUS CER. ooGacccanosccdd00c0K0Kc 15 White water-bearing sand.................... a2 RotalPa bolita. tarts oo cle oe Ge cute eee ele oteisic ts 145
X. Section at “ Lower Smith’s Banks,” 1 mile, south of Hawkins Point, Anne Arundel County.
Feet. Pleistocene. ~ : eal bOtes sec: Brown massive and stratified loam with a few well- rounded pebbles toward base..............--+-++++::- 6 Cretaceous. Qeuiceated argillaceous sand and sandy clay, iron crusts toward and at base where there is a local AG OIMUONHTMIAY Saobcdasucédcuondoaace eee e eee eres 4-8 Extremely dense, massive and tough, richly variegated Patapsco .. CTD YS ciate oe selierelens = less «1's elin) bye oinlo\e\.e ele) a1= 0) © si\e/s1 (ee) of =)=i 3 20 Continued downward by an artesian well at Ft. Armi- stead, Hawkins Point, as follows: Pine GeinGhy GeA7GoooqncneococdoodsucccusscodoudIS5qodn 40 Dine INTE Cains okeee es SelGucbo den GoUDoo dato OU Goo > oc DOS 20 White and buff mottled clay............-.--++--++-++-- 16 AN REND 2 ahaa ee Geib tins OE Chien OLDS In Guero CIOS 110
1See list of species in Tables of Distribution.
76 THE LoweER CRETACEOUS Deposits oF MARYLAND
XI. Section at “‘ Deep Ditch,” Schoolhouse Hill, Baltimore County, beginning 230 feet above tide.
Cretaceous. Feet. Patapsco ...Argillaceous sand, more or less iron-stained, with variegated clay and ferruginous crusts; ash-colored,
lignitic and somewhat indurated toward the base.... 10 Slightly indurated, ferruginous ledge, with Jeaf im-
pressions and casts of COMES...............2-200ees 1
Arundel ...J Drab-colored clays, with beds of lignite and white and brown iron ore, containing occasional fern impres- sions; teeth and bones of dinosauria; basal ferru- ginous ledge. Hxtensively mined for iron.......... 50
(Compact yellowish, reddish and variegated sand, lo- | cally carbonaceous; brown clay containing flakes of | iron ore (hydrous oxide); lead-colored clay with indeterminate fragments of plants; ferruginous sand- stone ledge with “pipe ore” (corrugated iron stone), silicified trunks of Cycadeoidea marylandica (Font.) Patuxent .. WaT Gna oe SUGU Soir, aie ieratieta seekers esate (os iak caes ooel pepedeeere nein 30 Dense jointed clay of great variety and delicacy of tint, red, liver-colored, and white predominating; “ paint rock” (red ochre) and lenses of coarse hard sandy arkosic gravel with balls of white clay and silicified
WiOOG ois Pai Gre aps Snake otal» atausBentiay SeWay ate renee onettone teal soe Ee 20 Cross-bedded sand slightly carbonaceous...... eas more ate 10 LOAN ranionyAMen TOON MAbs cigoa dbs cap oe > uno Hoo Sono bela uct 30 Crystallines “=: -Gneiss; exposed) near Arbutuss a. -eroen cece ieee TOted: hc asakiee:dvens cue sereee hsnaoe cuss Seu etn Tae SHS meee 151
XII. Section of “Red Stone’ Baltimore and Ohio Railway cutting near Lans- downe, Baltimore County, 140 feet above tide.
Cretaceous. . Feet. Arundel ....Drab clays, iron-bearing in the immediate vicinity.... 10 Patuxent ...Buff, white and richly iron-tinted sand and clay (the
sands at times indurated by iron) white “pipe clay ” ANG Ted OCHTORs Pest ce eal ilae eee Sie Ea ee 30 D0) Se Deer ae re a ee ire tad eRe oA ell AIO Ei ete RC al 40
XIII. Section at Reynolds’ Iron Mine, Piney Run, 1 mile south of Hanover, Anne Arundel County, beginning 100 feet above tide.
Feet. Inches. Cretaceous. White and light brown sand and gravel with ITONMSLONE <CLUStS since oc ec ee oe 10 Patapsco ...J White and variegated argillaceous sand, clay and red paint clay, more or less indurated ALI DASS Ge iis Ae ae eta eke rl ramet es kies @ Ugn OAT naa 10 Ferruginous ledge more or less conglomeritic. . 3 Arundel ...... Dense drab laminated clay, at times lignitic and with occasional undeterminable fern ‘impressions. Nodules, flakes and ledges of carbonate of iron in many courses (partly determined bysborins)Goeso see noe eee TQ
MARYLAND GEOLOGICAL SurRVEY
~—
XIV. Section at “ Timberneck Iron Mine” on Licking Run, 1 mile southwest of Hanover, Howard County, 200 feet above tide.
Feet Cretaceous. Reddish sand somewhat gravelly with corrugated iron Patapsco SANGSLOMCUaet cise sia ae thane shard Beclisco ele wie'ble Ge cbt ye. 12 | ELSE argillaceous sand and compact sandy clay SMELL Hees CLA AD CILGLSirrscepera.svexe a Jo'aleve 5 a0" whee ove ¥¥inlb ws Seo y 20 Arundel ...... Drab lignitic and at times pyritous clay, very dense, and carrying pellets, nodules, flakes and ledges of iron carbonate to bed of Licking Run............... 100
Patuxent .... White clay, exposed in bed of Licking Run
XV. Section at Baltimore and Ohio Railway cutting, between Jessup’s and Montevideo Stations. beginning 290 feet above tide.
Pleistocene. Feet. Sunderland .Loam, gravelly loam and ferruginous conglomerate grading into sand and gravel at the base.......... 0-15 Cretaceous. Brownish drab clay with fragmental masses of hema- titic ochre carrying leaf and cone impressions... 2-6 Patapsco ..J Light colored clay, grading over into red and varie- AN EXO WGIE Rint etre ene en seen teen Teena ee arkansas, S 6+ TB OSI OMEON Cle ccap ee stcles tictate te sucites srckouajudars versa aha a tue tells) ov ates 1 Grave) RRS a eter ec etna cdcl Sa ousish Saavene ic neT akeliotavas haji, eucraee ae 3 Lignitic clay, carrying iron carbonate and dinosaur- Arundel Bas jan bones RCH omens ea chewed chokinnaxcushatevenancrsiletote feline btn iielatoelnietslnys 60 Light drab clay with “‘ white ore” containing occa- SOMA CASESHOly MIONNIS Cece eteieieieie = sieieiete erie steielelanela!- 10 Patuxent ...Generally loosely-bedded, white and vari-colored sand,
argillaceous gravelly and arkosic sand and sandy clay, with much interbedded lignite to and below levelwoterailwayethaCks ie xs sus sew preyste se leleieve 6.08 o,0) oe 60
XVI. Section at “ Old Blue Bank” iron mine, near Muirkirk, Prince George’s County, 230 feet above tide.
- Feet. VECO M A ers apo cucves 2 Surface wash consisting of sandy gravel............ 4 Cretaceous. Patapsco ...Mottled gravelly loam with silicified wood........... 12 Massive drab clay with septarian nodules of earthy Arundel ...J Siderite; bones of dinosauria near the base........ Highly lignitic lense with white charcoal ore........ 2 Tough pluer clays with wiatterOnes <= ee cleric = <1 15 Patuxent ...White sand, exposed by boring....................- 10+
“Peieaul. TEL OG) Soa VeSteh io is os bo roicido cs Oo OD oo COE ome =263--
78 THe Lower CRETACEOUS Deposits oF MARYLAND
XVII. Section at Florida Avenue and Sixteenth Street, Washington, D. C., beginning at 180 feet above tide.
: Feet
Pliocene (?). Red loam, gravelly loam and gravel with cobbles and boulderstoward “base! vie oe eee oe ee ee 8
Lafayette Reddish brown stratified loam, vari-colored loam and ie clay interlaminated with brown sand............... 10
Ferruginous gravel with boulders of crystalline and Ne ware SOCKS 2c ociatcoete nicer eee noe eae ee Ee 10
Cretaceous. Arkosic cross-bedded pebbly sand with clay pellets, Patuxent slightly carbonaceous in places...................-: 15 hishtereenish drab sandy clayee. ste oe ee on ero 6 A Bo) 1) eee ER et eee eae tee chante ts samnton re es lates ued 49
XVIII. Well section at Pumping Station at Soldier’s Home, Washington, D. C., beginning 200 feet above tide.
es, Feet Cretaceous. 1210 Wi 6) be hy ile eee eR A eae RL Meme trem eh eee 2 RCC ETA als sais ere dea eta r sie Si araba hale, aero aera omer eee 2
White omaviele as sc crirca S aaaree cee eee BR er eieeieeae 3
WTEC CLAY ee eid setteratite eae ay5 tak eee eR Ee nee eo 4
Mellow Clay <., 22. 8otiers sce Sow'e, eke eo eee ee SI ee 30
Black: loamy Sans fisccate nthe ee eee One eee 6
White gravel, water-bearing..........-cc0ccescscecetce 6
WHEE SATs ee Se ereies crererel Sone ene vewel aii oy ee eel ohoaayion eRe Z
Patuxent HE Yes eae) Fn anne SN es are earn Re rey eR Tec au eh PS Pun ue Ee Chinas Ole 4 Bluey potters, clays scincimne oot tar ae tee eres eee creer 16
1 B24 1 ee aR IRR A aha Eee cone UaciEh eS iO crcLortG Cotto Beata CHGS 2
Quartzssand= water-bearine..-.k cee orci ee 13
BTU GM CUA sees autensltare is, Serene dee Grea eae ae tusene oe or ae ere 50
Sand andzabundant waters... 2 ce eee ein eieeeea ieee 8
Gravelly (clay 2.3 eae clk ete en ea Cae SE 13
Gravelly, clay mixed: with sand: 2222525. - sce see es 2
SES OL GET OCK EEE oo aio i steneeet ieee RIA oe GT eae os nS 5
Crystalline Ppblard) Seranibe a VOCK sila nviCiM trate ie creer te 5 y Gravel and sand, water-bearing...................+00% i Hard Snieeer- head’? rock:aen sae aise eo ones 304
ROCA eros oes aun ene eS Oras OP eae EE OE ner Ie ee 478
XIX. Section at Hast Washington Heights, near Overlook Inn, beginning 280 feet above tide.
Pliocene (7). Feet. hatayette 2 boam Cand ora viclivee.\aciece citer skore cases co oreeeiare caer tare ere 15 Miocene. Callivient? cee: Fine yellow ocherous clay (“marlite”) closely jointed with occasional small leaf imprints, grad- ing into mealy sand, iron crusts at summit........ 40 Cretaceous. Matawan ...Dark colored, somewhat glauconitic sand........... 15 Light drab laminated sandy clay, at times carbo- WA CCOWS 2.50%, ceieie rs hears os ereislian ote vaushasl ah oneee le: o oper are venete 8
Magothy ..-J Toose buff, brown, yellow, gray, and white sugary sands, more or less cross-bedded, and indurated, with light drab leaf-bearing clay.................. 25
MARYLAND GEOLOGICAL SURVEY 79
Feet. Massive and stratified bluish drab clay, at times : lignitic and pyritous and occasionally blotched RIDAB So as ewabhy ood OCHTG. (0s Moris ne bras dee ee dees ou 10 White clay in local lenses. Massive and stratified light-colored and drab clay, interbedded.......... 10 Dense variegated and drab, jointed clay grading at Patapsco times into sand, lower portion more or less covered es by flanking of Pleistocene and wash.............. 100+ [Red and drab clay with ferruginous sandstone largely covered by flanking of Pleistocene and wash....... 70+ Patuxent ...Beginning 20 feet below tide. Cross-bedded arkosic sand, with interbedded clay, estimated............ 440 Crystallines ....At level below tide of 460 feet. ROCA semua Se aah Serie es, ae Sear elae ee iets eneretoe ates 744
XX. Section at Fort Foote, Prince George’s County, about 200 yards below Notley Hall Wharf.
Pleistocene. Feet.
Wicomico ...Sandy gravel with cobbles and boulders.............. 10
Cretaceous. f Foueh Veariera ted: Clay. cn: cuss ceeicrom al cree oa ole cuesen eters 12 Strongly cross-bedded medium fine grayish carbo-
naceous sand compact toward top with interbedded
Patapsco ..4 jenses of stratified drab or chocolate-colored clay charged with comminuted vegetable matter and occa-
sional well-preserved leaf impressions?.............. 30
Dense, tough, chloritic, variegated clay to tide........ 10-12
TP Oa letaset es Sotarene shor rae treo Seouak ede reas wiieteiet aie’ e. Sienesetovee 64
XXTI. Section at Fort Washington, Prince George’s County, at excavation east
of wharf. Pleistocene. Feet. WACOM COMM © OATSEHEERAVCL sizes tiakewcrcacrels Sie iortr seorene avons oh ote) elionowsien tote serene are 8 Eocene. AGW oss 3s Red sand with casts of Turritella, Dosiniopsis, Cyth- erea, Crassatella, Ostrea; etc. ...........cc cree eesccs 12 Cretaceous. Light variegated sand, slightly glauconitic............ 10 Matawan .. Dark micaceous sand with Cyprimeria densata, Cras- satella vadosa, Cuculaea vulgaris, etc............... 10 Dense, massive, jointed, variegated and drab clay, gyp- seous above, occasional ironstone crusts............. 55 Patapsco ..J (Exposed near wharf) light gray lignitic sand, with much iron stained clay balls and with lenticular pockets of dark gray lignitic clay carrying indistinct IMPLESSTONS ROLE DAWES re res euerercictele retetaroieannencersvetcdenaichen= 4 NING GCE waren a aaceaer oe nae Pokal ote oae Rh RTS Gin he tae 99
1See list of species in Tables of Distribution. 6
80 Tue Lower Cretaceous Deposits oF MARYLAND
XXII. Section at High Point, % to % mile below Glymont, Charles County.
Pleistocene. Feet.
Talbot.) sack. Thoam: (and se raviel sis.c, 4 s:oscicec baie ee aehete ae ley erases ue tere 15 Cretaceous. Interbedded buff and more or less arkosic sand, loose and cross-bedded, with light drab clay, iron crusts
cri aaa Of: st = eg Pe PE Een Mein De Gh ans Aero oe menace oie EG 20 ‘ Patapsco .-.JIrregularly interbedded brown and light drab clay,
| grading down to brown sandy clay................. poe sandy clay, with greenish-drab, chloritic, sandy Clay at tides... cael he See ae ee aie See eee ieee 55
XXIII. Section on Stump Neck, Charles County.
Pleistocene. Feet.
APRN OOE 5 oo oud Brown 2ravelly- loam cities coset atest ote seat tcuas® 3
Sand) eravel andecobblesesas5es- 2H. ae cenit eee 12
Cretaceous. (CROSSE Hele S compact sand slightly arkosic........... = Patapsco ../ Massive green chloritic clay to tide, with lenses of drab
clay carrying leaf impressions?..................... 4
TO Geir ecs aac, ahve see. ER Ss HE LOE ee eee 27
INTERPRETATION OF THE POTOMAC DEPOSITS
Potomac deposition was probably preceded by extensive base-leveling of the eastern side of the continent, with accompanying widespread rock disintegration. Stimulated by elevation and seaward tilting, the re- vived streams transported these materials to their present position. The fact that these deposits consist very largely of redeposited Piedmont erystallines, and, to a less extent of Appalachian strata, is what might be expected, but the circumstance that no clearly defined trace of re- deposited Newark materials has been found in the Potomac deposits of Maryland is somewhat surprising. From this we must infer either that the Newark was not to any great extent exposed to Potomac erosion, or that its materials were not sufficiently consolidated to permit of trans- portation, except in so finely divided a condition as to be unrecognizable. It is quite certain that during maximum Potomac subsidence a large body of Newark materials, especially beyond the limits of Maryland, was beneath tide level, and therefore not exposed to subaérial influences. Inasmuch as the Potomac beds themselves, particularly the basal ones, have since that date undergone considerable induration, oflen without
1See list of species in Tables of Distribution.
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE Vill.
NEAR VIEW OF LAYERS OF CARBONATE OF IRON NODULES IN THE ARUNDEL CLAYS, REYNOLDS IRON MINE, I MILE SOUTH OF HANOVER, ANNE ARUNDEL COUNTY.
MARYLAND GEOLOGICAL SURVEY 81
the agency of iron oxide, we may suppose that the subaérial Newark sandstones of that date, if consolidated at all, were considerably less resistant than, for example, during the early Pleistocene, in the deposits of which the Newark materials are abundantly represented.
The basal deposits of the Potomac Group, produced by the initial warp- ing of the continental border and described as the Patuxent formation indicate in their arkosic character their proximity to the source of supply, which was the extensively disintegrated Piedmont crystallines. It is assumed that the Weverton peneplain, upon which the oldest known Coastal Plain sediments were deposited, extended as a land surface to the eastward of the present coast line. The epeirogenic movement, which stimulated erosion and inaugurated the Potomac cycle of deposition was undoubtedly a differential warping, with the focus near the present Fall-line. This may have resulted in the formation of a broad, shallow basin near or below sea level, from which the waters of the Atlantic Ocean were largely excluded. McGee has compared the Potomac deposi- tion with that of the present Gulf of California, although the lack of any evidence of an invertebrate fauna in the Patuxent formation renders such an interpretation unlikely. A gradual tilting of the coastal border of the Weverton peneplain would seem more nearly to explain the facts, since it is well known that sea coasts with an almost imperceptible gradient like that of the present west coast of the Floridian peninsula, show characters identical with those coasts which are separated from the open ocean by barriers in the form of reefs or sand bars. It seems probable that the inner marginal Patuxent beds, which alone are avail- able for study, were largely continental deposits made up of an ever- varying and complex combination of fluviatile, wolian, and lacustrine sediments which merged in passing to the eastward with estuarine or littoral sediments. The well-rounded and rarely flattened pebbles are characteristic of fluviatile action, as is the presence of cobbles, often of large size, which are so prominent in some of the Virginia outcrops. The cross-bedding of so much of the arenaceous materials which pass horizontally into clay lenses and which contain rolled clay balls is also especially characteristic of fluviatile forces, and eolian forces may like-
82 Tuer Lower CRETACEOUS DEPOSITS OF MARYLAND
wise be called upon to explain cross-bedding, although it would seem that the latter class of deposits are practically negligible when the materials are considered as a whole. The quickened streams at the inauguration of the Patuxent built out alluvial fans with comparative rapidity and af- forded little opportunity for the preservation of terrestrial vegetation or of the aquatic life of the Patuxent rivers or lakes. The fossil plants which are so sparingly distributed in the Patuxent represent for the most part fragments of coniferous stems or coriaceous bits of foliage which successfully resisted the trituration of the coarse sediments. Only one Patuxent exposure, that at Fredericksburg, Virginia, has furnished an extensive flora, and this was contained in a single somewhat more argil- laceous lens of very limited extent. Elsewhere a considerable flora has been found in redeposited masses or balls of purer clay, which were evidently transported from their original place of deposition in the quiet waters of some Weverton oxbow or lake, and therefore antedate in their origin and their contained flora that which was contemporaneous with their final deposition in the Patuxent sands. That the contained flora is not appreciably different from that of the balance of the Patuxent flora indicates that this time interval, while long according to human standards, was short when measured in terms of geological processes. Such meagre fragments of the aquatic life of the Arundel and Patapsco epochs as are preserved, a few almost undeterminable fresh-water gastro- pods, tiny pelecypods and unios, indicate that conditions similar to those outlined above persisted until the close of the Potomac. _
The Patuxent deposits, like those of the succeeding Arundel and Patapsco formations, reflect in a large measure the character of the Piedmont materials which lie immediately to the westward. Where these materials were highly feldspathic the sediments are strongly arkosic. This is a very characteristic feature of the Patuxent deposits, and one which continues unchanged as far as eastern Alabama, a distance of several hundred miles. Where gabbros or other rocks rich in the iron minerals are found near the eastern margin of the Piedmont, as in the vicinity of Baltimore, the derived sediments are ferruginous, and this is especially noticeable in the concentration of the iron in the Arundel
MARYLAND GEOLOGICAL SURVEY 83
formation, and to a less extent in the Patapsco. Where the chloritic schists of the Piedmont are developed near its eastern margin, as in the northern Virginia area, the Patuxent clay lenses tend to be greenish in color.
The close of the Patuxent epoch was probably marked by a slight elevation of its deposits and a trenching of the surface by streams; or perhaps the process was merely one of differential warping. This was followed by a subsidence or tilting, which was emphasized to the land- ward by the occupation of the ancient valleys by swamp deposits. The tough clays of the Arundel formation, charged with lignitic accumula- tions, in which tree trunks are at times found erect with their roots in- tact, find their most satisfactory explanation on this basis. It was in these ancient swamps and estuary marshes that the iron, derived to a considerable extent from the adjacent areas of basic eruptives, was de- posited, first, no doubt, as bog ore, which by contact with the excess of carbonaceous materials was later altered to the carbonate and redeposited in its present nodular form. It was in these swamps that the remains of dinosauria became entombed. On this hypothesis the lenses of Arun- del clays represent crudely the ancient drainage lines of the eroded sur- face of the Patuxent terrane. The widening of the areas seaward may possibly be interpreted on the basis of lagoon deposits into which the Arundel estuaries merged.
The Pleistocene “buried-forest ” deposits of the Chesapeake shores may furnish some clue to the origin of the Arundel iron-ore clays, as well as similar beds in the Patuxent and Patapsco formations. The Pleistocene deposits of this character appear to have originated by the impounding of the estuaries by sand spits—a process which may be ob- served at many points within the Chesapeake and elsewhere at the present day. The closed estuary then speedily silted up and was con- verted into a peaty cypress swamp in which bog iron ore was deposited. Meanwhile the bay shore adjoining the mouth of the swampy estuary was gradually receding by virtue of wave action until the swamp mate- rials themselves were invaded and more or less cut away. This process was followed, or perchance attended, by gradual subsidence, which re-
84. THE Lower CRETACEOUS DEPOSITS OF MARYLAND
sulted in the deposition on the newly wave-cut surface of a new and later member. Emergence followed, and the waves of the Recent period are now actively cutting away both the more recently deposited beds and the basal remnant of the older ones, with their beheaded cypress trunks and. knees, imbedded in peat. In the basal clays of this Pleistocene swamp deposit, penetrated by the roots of the trees, one finds an occasional, im- perfectly formed nodule of iron carbonate, so characteristic of the Arun- del. When exposed to the air it rapidly changes to a bright vermilion ochre.
There is little question that some such process as this has figured to a considerable extent in the genesis of certain of the lesser lenses of drab, lignitic, iron-bearing clay occurring at various horizons throughout the Potomac Group; but the large scale—both vertical and horizontal— on which the Arundel formation, or “iron-ore clays” proper, is de- veloped cannot well be explained entirely by this simple theory. Land- ward tilting must be retained as the chief explanation for the Arundel clays until a more satisfactory interpretation can be brought forward.
The well-marked unconformity occurring at many points between the Arundel and Patapsco formations, notably in the West Hanover district, indicates emergence and a distinct erosion interval prior to Patapsco deposition, and the marked changes in the floras would seem to indicate that this interval was a long one, during which the Arundel sediments, if originally continuous, were removed by erosion from large areas.
The highly colored and variegated clays of the Patapsco formation, like the iron-bearing Arundel clays, evidently bear some relation to the great basic eruptive masses, plentifully iron-bearing, which lie to the north and west of them. This phase of the sedimentation is somewhat more prominent in central Maryland, where the rocks of this character are not only well developed, but nearest the eastern margin of the Pied- mont belt. It is also probable that these ferruginous Patapsco clays were also in part redeposited from the more richly iron-bearing clays of the subjacent Arundel. The Patapsco sands were doubtless derived to a considerable extent from those of the Patuxent terrane.
That the seaward tilting was not continuous or persistent in the same
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE IX
Fic. I1.—VIEW SHOWING PATAPSCO SANDS OVERLYING ARUNDEL CLAYS, CEDAR HILL MINE, TIMBERNECK, I MILE SOUTHWEST OF HANOVER.
FIG. 2.—VIEW SHOWING LEDGES OF INDURATED SAND IN THE PATAPSCO FORMATION WHICH IS OVERLAIN BY GREENSANDS OF THE AQUIA EOCENE IN CUT OF R. F. & P. RR, NEAR AQUIA CREEK, VIRGINIA.
MARYLAND GEOLOGICAL SURVEY 85
direction is evidenced by the varying character of the deposits and the statigraphic relations which the several formations sustain to each other. In the succeeding chapters the surface configuration, both of the crystalline floor and of the Potomac Group is discussed, and some pos- sible interpretations advanced.
The greater thickness of the formations of the Potomac Group along a belt somewhat to the eastward of the Fall-line may have emphasized the downward movements in this portion of the Coastal Plain during Potomac time. On the other hand, the gradual removal of the weight over the Piedmont region by the removal of its residuals has possibly occasioned an upward movement of that area as well as of immediately adjacent Coastal Plain regions. The accumulating results of these ten- dencies, particularly the first mentioned, from the beginning of Potomac time until the present, have been the weakening of the crystalline floor near the landward border of the Coastal Plain, accompanied by monoclinal folding and even faulting on a limited scale. The studies of McGee in the upper Chesapeake area, and of others to the northward and south- ward, fully convinced him that displacement had actually occurred, al- though no very definite evidence was adduced in demonstration of the same. Other writers, including Fontaine, however, believe that we have to do merely with sedimentation across a pre-Potomac escarpment. In the opinion of the authors of this paper, the Fall-line phenomena in Maryland, and elsewhere, afford considerable evidence of actual dis- placements. A number of carefully constructed vertical sections on a large scale have been made across the Fall-line zone, and these show in nearly every instance evidence of this.
Evidence of the actual displacement in the Potomac beds is very clearly defined in the vicinity of Relay, Maryland, and this is further strengthened by the fact that the Miocene beds at Catonsville, near by, lie considerably higher than the normal dip of the main body of the Miocene deposits calls for.
At the openings of the Maryland Clay Company, at Northeast, Mary- land, there occurs a well-defined example of an anticline in the Patuxent beds which is believed by Ries to have been produced by the hydration
86 THE Lower CRETACEOUS DEPOSITS oF MARYLAND
of the subjacent feldspathic rock in the process of its decomposition into the residual kaolin mined at this point. Though the scale on which the folding occurs is small, the phenomena afford a suggestion as to the possible causes of some of the lesser irregularities in the Patuxent beds which lie near the crystalline floor. —
Surface Configuration of Crystalline Floor and its relation to Potomac Basin of Deposition
The basal beds of the Potomac Group rest on a more or less uneven surface of crystalline rocks, in which certain of the more important drainage lines of the present day were already established, as is shown both at the marginal contact and by the well borings near the landward border of the formations.
The great increase in the dip of the Patuxent and succeeding forma- tions along the Fall-line has already been alluded to, as well as the evidence that it represents in part at least a fault scarp.
It is significant, however, that there is a marked though less pro- nounced decline in the dip of the strata eastward of the Fall-line all the way to the seaward margin of the Coastal Plain. The evidence for this is furnished by the deep-well borings in Delaware, Maryland, and Virginia, the number of which is not as great as could be desired, al- though they all show, without exception, a progressively lessened dip of the beds as the distance from the landward margin increases. |
The following wells of the middle Atlantic slope reach the crystalline rocks and show the following rates of descent of the crystalline floor:
Distance from
point where crys- Depthofecrys- pate ot
talline rock
Location of well. surlce 3 aches surface bel ow oeeee ne Miles. Feet. Feet. Ice works, South Wolf Street,
Baltimore i neces aeee ie ccicee 34 151 200 Baltimore Copper Works, Balti- :
TUTOR E! se vusheg shereieratteace nie seeker 2 187 93.5 Farnhurst, Delaware ........... 2 111 55+ Middletown, Delaware ......... 1 452 Sal Sandy Point, Virginia........... 2 270 135 (yee, Whee, Gooocosucooss 2 210 105
North End Point, Virginia...... 72 1,162 15.7
MARYLAND GEOLOGICAL SURVEY 87
These records indicate a rapid slope near the Fall-line with a lessen- ing seaward, although actual elevation is suggested in the crystalline floor in the Middletown, Delaware, area, which may represent an exten- sion of an axis from Jron, Chestnut, and Grays hills to the southeastward. _ They also show an actual thinning of the Potomac deposits to the sea- ward, as shown by the well at North End Point, where the thickness of the Potomac beds is only one-half the normal thickness at the outcrop.
The record of the well borings becomes of the highest significance when it is remembered that this crystalline surface has been receiving along its seaward margin progressively greater and greater loading through de- position since Potomac time. ‘The conclusion is readily reached that subsidence took place gradually, and that any barriers which existed along the eastern margin of the Potomac basin were depressed below sea level. -
Marsh and McGee, as well as most other writers, have expressed their belief in such a barrier, although not adducing any further concrete evi- dence of the same than the non-marine character of the Potomac sedi- ments. McGee has suggested, as above stated, that a Potomac barrier may have been comparable in character and extent to the existing penin- sula of Lower California. Another possible, although perhaps less plausible, interpretation of these phenomena is found in the hypothesis of incipient folding in Potomac time.
Such interpretations as have been suggested in the foregoing discussion may be understood as but an imperfect and more or less speculative at- tempt to reduce to language a long-continued series of events which in the actual complexities of the interacting factors involved baffles de- scription.
Surface Configuration of Potomac Deposits and its Possible Interpretation The records of deep artesian well borings to the eastward of the Po- tomac belt indicate some clearly defined irregularities in the rate of decline of the Potomac surface. It will be seen from the following table that only a single record shows a greater decline than 25 feet, while
88 Tue Lower CRETACEOUS DEPosIts oF MARYLAND
most of them show a descent much less than this amount, in one in- stance (Crisfield) even less than the observed average landward dip (124 feet) of the Eocene deposits which immediately overlie the Potomac beds to the southward.
Distance from Rate of : point where Depth of deecn tin Location of well. Potomac surface below f as surface reaches tide level. ewe sea level. Eee Miles. Feet. Feet. Rock Hall, Maryland............ ra 240 34 Claiborne, Maryland ............ 19 440 23 Tunis Mills, Maryland......... 24 430 18 Tilghman’s Island, Maryland.... PAL 400 15 Gloucester Court-House, Virginia 38 600 16 Williamsburg, Virginia ......... 38 550+ 14.5 North End Point, Virginia...... 62 920 5 Crisfield, Maryland ............ 91 964 10.6
According to these records, there is a marked lessening in the decline of the Potomac surface far to the seaward. When the surface of, the Raritan formation is likewise considered there seems to be an actual rise in this surface in the Eastern Shore of Maryland and Delaware, between the Chester and Choptank rivers, although it again declines east- ward a little farther seaward, as shown by the boring at Gloucester Court House, Virginia. Whether we have to do with an erosional irregularity in the Potomac surface or with incipient deformation, the facts at hand do not permit us to determine. If the irregularity is due to the latter cause, the axis of the anticline would not seem to be coincident with that of the peninsula cf Delaware, but would cross the latter in a northeast- southwest direction. A depressed barrier, such as has above been indi- cated, may well have served as the seaward buttress in such deformation. Whether there may be more than one of these axial prominences in the Potomac surface is a question of much interest, but which cannot be answered with the data at hand.
The lessening in the descent of the Potomac surface far to the seaward, as indicated by borings at North End Point and Crisfield, is in general in harmony with the relations of the subjacent crystalline floor above described.
MARYLAND GEOLOGICAL SURVEY. LOWER CRETACEOUS, PLATE X.
Kee
Fic. 1.—VIEW SHOWING MASSIVE VARIEGATED CLAY OF THE PATAPSCO FORMATION, NEAR HAWKINS POINT, ANNE ARUNDEL COUNTY.
Fic. 2.—VIEW SHOWING PATAPSCO SANDS AND CLAYS OVERLAIN BY PLEISTOCENE SANDS, B. & O. R. R. CUT, ROSEDALE HILL, BALTIMORE COUNTY.
MARYLAND GEOLOGICAL SURVEY
89
DISTRIBUTION OF THE FAUNA AND FLORA.
The following tables show the geological and geographical distribution
of the animal and plant remains which have been collected in the deposits
of the Potomac Group both in the State of Maryland and in the contig-
- uous areas of the District of Columbia and Virginia. The species recorded
in these tables will be fully described in subsequent chapters.
TABLE SHOWING THE DISTRIBUTION OF THE ANIMAL REMAINS.
Arundel.
Patapsco.
Maryland.
Near Muirkirk.
Bladens- burg.
DINOSAURIA. AllOSQUTUS MEMiUS......- 46+ CYeEOSAUrUS POtENS......-.+6+ CElUTUS OTACUIS ....6.. 006055
Plewrocelus Nanus..........-
Pleurocetlus altus
Peewee ee ee ne
Astrodon Johnstoni
Dryosaurus grandis.......... Priconodon crassus ......... CrocopiziA. Goniopholis affinis ..........- GASTROPODA. Bythinia arundelensis......- Viviparus marylandicus .... Viviparus arlingtonensis .. PELECYPODA. Cyrena marylandica
Unio potapscoensis..........-
sere eeeelee
sewer cone
we eeseee
seco resele
sees tees
sec e cee
Cs i iii ir ae iy
ee i a ry
|District of Columbia.
eee
wee
ee eee ee] seer ere-| ress sone
See vote leew eee ee [ewan oer
ee ees oe | eee ones
Ce GC ee
eee
eee
Virginia.
White House Bluff.
Washington.
Per ereees serene seeee |ses os sesece
See wees
ee ry
ee
er)
es ris
eee ee ee Oe ry
ee i id
Fees e eee e weer ceee sees lease
The fossil plants which are much more abundant than the animal re-
mains, are recorded in the tables which occupy the following six pages. All those occurring in the District of Columbia are listed as well as
certain forms from the Potomac deposits of Virginia, although not all of
the forms which have been found in the latter state are included.
90
MARYLAND
THe Lower CRETACEOUS DeEPosiIts oF MARYLAND
PATUXENT
DISTRICT
COLUMBIA
OF
VIRGINIA
Ft. Worthington (Baltimore)
Broad Creek
Springfield
Clifton (Baltimore)
Terra Cotta
Ivy City Montello
Lorton (Telegraph Station)
Cockpit Point
Colchester Road Potomac Run
16th Street
New Reservoir Kankeys Woodbridge Fredericksburg Alum Rock Dutch Gap Trents Reach Neabsco Creek
FILICALES
Schizaeopsis americana Ruffordia acrodentata Ruffordia Goepperti
Acrostichopteris cyclopteroides Acrostichopteris adiantifolia Acrostichopteris parvifolia
Acrostichopteris pluripartita Acrostichopteris longipennis Acrostichopteris expansa Knowltonella Maxoni Dicksoniopsis vernonensis Cladophlebis Browniana Cladophlebis constricta Cladophlebis rotundata Cladophlebis virginiensis Cladophlebis parva Cladophlebis Cladophlebis Cladophlebis Dryopterites Dryopterites Dryopterites Dryopterites Dryopterites Dryopterites virginica Aspleniopteris pinnatifida Aspleniopteris adiantifolia OnYyChiODSisnlGtilODM mea eee Onychidpsis psilotoides Onychiopsis brevifolia
Onychiopsis Goepperti Onychiopsis nervosa
Sagenopteris latifolia Sagenopteris elliptica Sagenopteris virginiensis Tempskya Whiteit Taeniopteris auriculata Taeniopteris nervosa . Scleropteris elliptica
Thinnfeldia Fontainei Thinnfeldia granulata Thinnfeldia rotundiloba Thinnfeldia marylandica
LYCOPODIALES Selaginella marylandica EQUISETALES
Equisetum Lyelli Equisetum Burchardti ....
CYCADOPHYTABE
Cycadeoidea marylandica 2 Cycadeoidea Tysoniana
Ce
Ce rd
Cy
Ce CC ed
macrocarpa pinnatifida
cystopteroides elliptica
CD
CeO CC eC
Co
Ce ee
eee eee ee ee ee ew ww tee ele
CC
CeO
ee ee ee ee eee eee jteee
Ce
i
CC
CC i re Cc i
eee ee ee ee we ee wee ww ew alee
CC a
eee eee eee ee ee ew ww leer
eee eee ee ee eee ee ew levee
eee ee ee ee ee ew ws ee
ONG OEGTUIG Re comerteae ntencecton aang hicto wat ke Saale é
OC i CC aC
Ce
Ce ea ey
see eee ee we we we ww ww ww [tee lee eeieeeelsceniere
8
} Found eroded out of Patapsco formation along Deep Run and Stony Run and on Patuxent Neck. 2 This species occurs in situ in the Patuxent formation near Arbutus.
ee te wee ww ee we we ww ww [te eeleeerlseeelenselessrloeven
ee ee eee wwe eee ce ww [tees lecceleeesieresiseesieroeleresiense
Pasi Sten
rar SRR R RRR RRS
#
lee eeleceleecle
g6e Eg
Dl kee RRS
RR HEE RHO:
eleeelece
eleeslene
Localities for other species of
91
MARYLAND GEOLOGICAL SuRVEY
PATAPSCO
VIRGINIA
wo}}Og doacy
WSOd ONT oyooag,
Yoo) Binby_ Ia TE BOD Te
Surpury sopqgunqg —
seleee
MOTO Ujdeyary
we alew alee eaeele
%0H [PH
BNA esnoH oTA\
uouIeA “IV
UUl YOo,aAO
YOON duns
sles elene
quow ATS 180N
(guid S$191SOY) 21007 WOW
ITH 1BS0UTA
TOJSUIYSEM “WA
Suv TOM
MARYLAND
(a10UII}[V) LTH [e10opot
yooulg ApPPNI
juI0g avidog
seleee
INH sAévay
eeele
ARUNDEL
VFIAWoATOD
ZO LOIMLSIG
peoy jedvyg sueend mopsuery
alepazvAly
eeleeele
YALA
90] 00)
auUMOpsUeT
WO0}SUT[AV
T9AOUB HAL
*
dot dh
ayes UWMOIg PrvMOoy
aul, Sprousoy
eleealee
MARYLAND
sul, SUBULIOS)
selreclesels
sul Saq0H
a1B1Ssq AoTMog
IleH sedog
elewelecaleve
MoIA Avg
a10UII} [VA
se elew slew alee eles
se eleeslewolane
eles eleeels
sale tales elaeoleveles
Cycadeoidea are not tabulated, since none have been found which have not been reworked into younger deposits.
1 ea THE LoweER CRETACEOUS DEPosiITts oF MARYLAND
PATUXENT 4 DISTRICT
MARYLAND OF VIRGINIA COLUMBIA
Lorton (Telegraph Station)
Ft. Worthington (Baltimore) Cockpit Point
Clifton (Baltimore) Terra Cotta
Ivy City
New Reservoir 16th Street Colchester Road Wredericksburg Alum Rock
Dutch Gap
Montello Neabsco Creek
Broad Creek Springfield Potomac Run Kankeys Woodbridge Trents Reach
CYCADOPHYTAE—Continued Cycadeoidea McGeeana' ........
Cycadeoidea Fontaineand ..........e ee eee |eveeles : 3 Pe eee Sea nein oa eerlioca lara eaclicwclic- - Cycadeoided GOUuCNETiand ...eeeeeececene lrveriers s a Bid ero paolo olean meclaeclitadinrclions!|- - - LOU Go aDOKE (ONUUGRAL Ado mopo Gob b oon 00600 eo bo0ulloodolen 5 allo SpElasaldddlondladdlisoo|soele-oloocliclicc - Cycadeoidea Bibbinst ........... era enaasveireneal| evavall seated es , ulster saela| ae oodles «| deeleeroleee Cycadeoidea.Clarkiana .:.......ecececeee leevelee : s 3 : Sialledai[sitielts ell eco el] ecrclllverel a al een ea Cycadeoidea Fisherad€ ...... ese cecesces |rcrelecealas ‘ A val seve PE Bees Berl eereiaess| esa icles Geel ics alle = > Dioonites Buchianus ..... booooad 50060600 |sodullao Balleaonlh 4 Py || pilbadlbe a ijoodipan|oool es |) elles. Ctenopteris insignis .......... Sedo obo. pl lbobolae 2 a ne BIS eonsoa|| £3 lool oc a Ctenopteris angustifolia .............. Srencn| Saoolles ;: aril se x |. Bolo bw a valaem Ctenopteris longifolia ..... Ruawa sieve orate aereiene : Bllepalloos ial Ao:
Ctenopsis latifolia ........... Miaroneiectenevene Zamiopsis dentata .......... Soe ara tene a cals Biol cho Senco aera ero satel lseavell a erecalltaa Zamiopsis petiolata ........... bao go ceo 0 locuolococlsecloccolleone(aacclleaocloacaloooale ollocallancloadlcoslicoc
Zamiopsis laciniata ........ susuiateneusteevenece Nilsonia oregonensis ............ sega etek sSaldodalbacuidowallocoollesos CJA eee ay Sealact j Nilsonia densinerve .......... Lion en eee 56 Ibocoloodclesosponollooodiascolooadioancliaccullesoldsofsoolanaicacoocll cs Jacell- Zamites tenuinervis ......... ond o Bi /lsapollopdo|loooulccde|laaaclsodn|louod|) arollosoc|soollova|loccinool es dicucl es lleaall [fsccis-- Zamites crassinervis ...... Sake ousucious axerevsuete dacad|rcad|sccullsoddlonouisorol|isoanlouolloooalaodiaoulscol) ea] es Jeool! zartie IDO OULD GUGUOKIUSISS too Gln oo cbc ooo olboadiooralovodaccclacsallcocclooadisoecllacoullood|oonlosclMoniinac|oacleocl|os Cycadeospermum marylandicum .......... Seca kwon Sopaloonel Good mone cooclleer nilsaaglibo ts j re
Cycadeospermum obovatum ............- so difesatara'lffecarelleaueten| steel | eteyeral late ravel|levsiarall siete ioteaetel axe OMA VAM DONO MUXOUTSULID. (Sb abo odo babu oo cau lsodolbodclbooclosdnllonbsllacaclocodiocosiosnalec Cycadeospermum rotundatum ............ ogdloodglmasoloosslicacalacackiaecloonailoouclica OOM TOS DAP OM OS NRA O, “oo oo pan oaeb oc lsadclocoolsncdloocdlossclocaciooosioacclloaonlosollod Podozamites subfalcatus -............... 6 |lssdulbcodlsoodloocdledcaladaecaa|loaus|ooodlecdl) & llacalosullesa|eco|loo ile LEONEL, CONUOLNIS obo bdonbeeooc0600lbocalbocalescalaccalacnlocgall s0claoccloonal[esall 23 loonlleallooo)locc|locaiacs Podozamites imaequilateralis ..... er tetener ais éadolpaddlecudloucdlocucleosalcooelaoee|scodieoclocaliea |) es ||-eaillocalsoclics Podozamites distantinervis .............. p0ndloooollsooclosnalloocel| ecallaacoleosell ga lscalleccloanl] a |jocs|oc Podozamites Knowlton ...............:.- BacdloonsSovalloccas bordlsocalodociacoallaconiaculioacldaclicadloddiisc Podozamites lanceolatus ................ so on|aodo}ooon|loocalonaclonaoloonaloaoallocoaeol gy llcoallooallecioe
GINKGOALES IEOEU: jOUOSB co ooceoucakouncoonboaoosee Hoo] Huoolkeoeaoalbenelsocs|aaae bonallbcccldooloediood|scallooclossilosallocall 5 [seallec = CONIFERALES
. O06 1 St . ° .
O00 Gintecu stile ara
% fos ror es
IMUCRO NIE UOC OLEL “Sons oobiao on bm 80 40 logbolbadclsacalsacolloacolsoncloacaloacsileooulecal ele
Nagciopsis angustifolia ...........e.05-- Fa Sel shay a bi ctayaielnpatrs fete: etall aver oval siecall stec evel] megeraltetas lenses PUGS Albeit usec Galloscilos: INK ECO SOS) CEO OKUAY So oioln oo coop doo bb 00 bnddlagnaloonaleacaldnoslocoslbaon|anaoloosolasolecoll 2s |} es ooc}iooal|-es |doal! ce feodl!s- - Cephalotaxopsis magnifolia ........ cooode Socul dod bean wane eons opad ond coud ssoclsaolcociasd lichiioon Pellesolies loaalec - OF NO OARS (ORGS Bob ooo on oo bob 5b Soodlbanoleaodlscccloosallocoeloaccloaoaloccallose adel S606 Bi Ban| be wllaociiccc Brachyphyllum crassicaule .............. snuclbsdu| Cosdlacicn|joodelbaoolandaladediisedalacdiccaladaloaalosellovolleudiooa"” ef cs fie - _Brachyphyllum parceramosum .......... Sj lNocnlbocgalsoodloscclcoas|oeoulbooel| ery iooodloooll 2 Bay Bad Bt on) moe) iosclloeclioos Arauwcarites aquiensis ........+..2++.5:+-- Snellen os| Gondlasonladcslaouplodecipanclococlacnioon retell fors'|leistst| terest inkersl| OPs ail rail ete Araucarites patapscoensis ..........++.6- RADU OCOS odalGong loocolbodolauchleboollooon|oastogo be slte soa 'sters' [ness ear ea Abietites macrocarpus ............-...+-+ col ¢3'Ilo a allbsacticdoal[oncaca se areod
Abietites Vongifolius oc tect e tet cee ee sondllae salle 5 Salter ee délloaallaes Eales
AIDIETILES fOLiOS1 Sh terete en tna tote Sodllovb alos hie Selle poolicooolgaallead poalogals
Abietites marylandicus .............. sid eveveteleaeneall nee AAlieee Bal ber lena iderad tae laaio inoalonalloom
PINUS “VErNONeENnSisi ac. ost e enone Syed eisterel| a eel Sieve balloooollon Salida dollacol kecloaaloaa aco
Cupressinorylon Wands se. cee. ease ee l\eceslencelaneal) 4 lee 5a, 3 honolsanalaadisa5lbooisecls
Cupressinoxylon McGee ................. sooloaouedeallos pulboud les loocallood|sedloen| ool
Frenelopsis ramosissima ...........++:5% Spo cool bood|ooun bepalanad boaclecocloocullocsiicanlagcloaollacc|os
1 Localities for this and the following species of Cycadeoidea are not tabulated, since none have been
MARYLAND GEOLOGICAL SURVEY 93
ARUNDEL PATAPSCO
DISTRICT OF COLUMBIA |
MARYLAND
MARYLAND VIRGINIA
| | | | / | tel | (os a ie | i | a | : i z / I} | homies Sate | | ~ | } / / i LT yy ft} ttt ty 8 tl | ele A | | | call | | 6a | he 3 | / a lo 8] © o|e =| / =m | | i | | | | i= | 3] | # a| |e 2 2 | a4} | 2) |SIs! leg 3| a] ie _| 8} 2\3/5| 2 e| | a} (elsie!} |S] ol sislsialai |S Si le! | 8/8 e|e|alals = alEl |wlol (Slslclsim| sislZSl Ble clsisielsielsiz) ale S/S el alesis Si) Si 2/9) jaie) st |S) 1 Ble) | 3) aA) BR) ola) 2) 2/0) | ols pl ale! ele! 2 S| @|s| 5/9] 2] | n a| o s/f )/S} alo] ® Mi s/s) 2) =| Pleo ea Si slB/ 6) 8) 2) 9 SelB) al el al\o) Sse! & nl glale|s oa) 6a) E) | ae) =)" Se BBS E/E 8) a) 82/8) 8\e/ 2) a] 8| 2) 6/5) 9/5 a} & g/2|2lslalsla| S|=1e A 3 ov ov — Kl @/ oO = S| hl] oO} DO) 2) Hla} oO] we > SIP S| Sis S|] Bla © Alalala midlalmalm<|SSisiz/3Sio/ais Elm) ele |) Ol S/F) mo a\E)<)a)e|\6 Sa SSO Lae | | = = ee A oe) a Da) al | | baal | by / | ) ) | | | | ee tleveleceles selese eleeelecchevcisce elewvleeleccleccliessieceleusiesciae aleeal : eeeleccleeciscciecs Hite ewww ew elene ? we elee tise else cise eleesieeelicesisesiec or we slecsiseticccieue t]reeleceleselenelecclecclocclocelecs| @ lecclecelecelovele se) eh tless eleeelecslee elec eiecelecel(ecvlecelece tle eles eleee 90 Dig nic sele oe orien ewiee tiene Pee ee ee ee ee ee ee ee a wetleetleseiseviee el e « wiele pal me ele cele slew wise eleeelereieseleeelseeleeelecaleceleesieeciereitee! HE leeelerale eee tsefeeafeseficalers]icelens|osa[ers|osafersfoeafere] w oveleeslirelesslac. A GI e a eaclocelcealveslaaclecc[eosloosleecl g lews[ers|ess ee IN MEU tclanicis|ciclelaiee|sicc|sselese|seelesc|: £ low a5) Bod bn . ; eee cele clo alos e|vec[ese| qe loaeleccleccleceleoe[.. oles de j ME eel aie fecel ee |e cal oe|uolenelonclana|ooelecel ge [ovale oe]-« GIR Wesel "ies selec alee sinc elsrelseeleet ise wiensieselereleseleseisesioes sfeee| | ele celecs snes | j Be elecciccelece|-colecslecaiecciecciscciecclecelesclteclsen A ct bon Mar ele ese . | | MME ee lorcclolne clan ale aa|secleo fon aloce|see|re odes ola aleea{esalens | | | | : | | | | | | eleaelece| & elec elenclece| He leeslecs alee eleeeleeeleceleeeleeelese!| & | R | & seine eleeeleeelecelecelecelene! & leeelene eee ee ee ee ee ce ce ee ee ey * * eee eeele . ee eee ee wine oe eee wee oe. PeralstetateielWlsiets|sle'shnsis|sicalesnlreslecalerclecsiecclecelnccl(sesieccless[ecclece| & on ee ee ee ee ee ee ee ee ee ee ee Aa50C oa hoe Bec fec lec aleccleccle selec clecelacelevciesclecclecclesclecelecelscoiecsinee| | & | # . MMM IS Morales (isc scalsocleccleca|ccslowelesclooclecclveclsesfocleoslese t
found which have not been reworked into younger deposits.
94
THE LOWER CRETACEOUS DEPOSITS OF MARY
AND
PATUXENT
MARYLAND
DISTRICT OF COLUMBIA
VIRGINIA
Ht. Worthington (Baltimore)
Broad Creek
Springfield
Clifton (Baltimore)
Terra Cotta Ivy City Montello
Lorton (Telegraph Station)
Colchester Road Cockpit Point
New Reservoir 16th Street Potomac Run Woodbridge redericksburg Alum Rock
Kankeys
Dutch Gap
Trents Reach
CONIFERALES—Continued
Frenelopsis parceramosa ~ Sphenolepis Kurriana Sphenolepis Sternbergiana Laricopsis angustifolia Arthrotaxopsis expansa Arthrotazxopsis grandis Widdringtonites ramosus Cedrus Leet Sequoia Reichenbachi Sequoia rigida Sequoia delicatula Sequoia ambigua
ANGIOSPERMAE
Cyperacites potemacensis Plantaginopsis marylandica
Alismaphyllum Victor-Masoni Populus potomacensis Populophyllum minutum Populophyllum reniforme Nelumbites virginiensis Nelumbites tenuinervis Menispermites potomacensis Sapindopsis variabilis Sapindopsis magnifolia Sapindopsis brevifolia Celastrophyllum denticulatum Celastrophyllum parvifolium
Celastrophyllum tatifolium Celastrophyllum acutidens Celastrophyllum Brittonianum Celastrophyllum Hunteri Celastrophyllum albaedomus Cissites parvifolius Sassafras bilobatum Sassafras parvifolium Sassafras potomacensis Araliaephyllum crassinerve
Araliaephyllum magnifolium
INCERTAE SEDIS
Hederaephyllum dentatum Ficophyllum serratum Ficophyllum oblongifolium Proteaephyllum reniforme Proteaephyllum ovatum Rogersia longifolia Rogersia angustifolia Rogersia angustifolia parva
ec OC CC i CCC) eC cD Cee CC CC a Ce Ce ) SC ec Y
cici/aloMetivtieiieliaaltoitelelienels Coco DO CO dOGOO aiisileltel.eMevloreliekejiele Hom OD Oooo oOo OooO Ou oO Sec ae ee eeNsielfelieiellaleleliolesatlellelie s)ie) = te)"e) 6) 6) «| ie le elle) so) «) «0
Ce ee) eo ee eee ee eee eee ooo
Ce ee CC Cr Cc CD Ce er POU o OOO So o5 50
cece eo ewe we ee ee te te eo eee oe
eee ee ee we te ee ew ee ww [tee
eee ee eee ee we ee wo [seen
ee cee ee eee we wee ww joe
eee eee eee eee ew ew we ee eh lee
CC Ce rc
ee eee cee se oe ew lee
CCC ee I
ee ee eee oo ew ew ww let eeleoe
Aristolochiaephyllum crassinerve ...... shone Bi ae a ae Aristolochiaephyllum ? cellulare ......... NARS
aileliel/e)lalletlellellallatlclielictl |aleilell(alelele){feinlele]|(olate)s)|(eleits)
wee ee ee ee ee ee we ew ww ww [ete eleeeslssesiense|reeelsene
CeCe ee eer ee ee CC ea a a
* * * Deel * x *
¥
De eR RS
Neabseco Creek
MARYLAND GEOLOGICAL SuRVEY 95
nt
ARUNDEL PATAPSCO
MARYLAND MARYLAND VIRGINIA
DISTRICT OF COLUMBIA
| |
Hollow
x
kapin
dale Langdon a Creel
Brooke
iver i
Federal Hill (Baltimore)
Wellhams Fort Foote (Rosiers Bluff)
Howard Brown Estate Queens Chapel Road Grays Hill
White House Bluff Dumfries Landing
Bewley Estate Hobbs Mine Germans Mine Reynolds Mine Lansdowne Poplar Point It. Washington Vinegar Hill Near Glymont Stump Neck Overlook Inn Mt. Vernon Hell Hole Widewater 72-Mile Post _ Deep Bottom
{| Baltimore Bay View Soper Hall Hanover Muirkirk R
_| chint
Aqu
te
wwalesaleaetenelecclecelereleselesclecclerelovclecelesslecalacalesslacslecelecslesclesaleselesalecelessleceleseleselacsiene lees ease pineal) Ietollacblleanlned lace eee HK fee ele selec clencleceleselacelerclevcleccleceles cle sles Baa Kad tlessleeslenele ale.ce seelee eters! fees] He lee else eleeeleve| & DEO USCO IE Cpe t pen eee O16 O0 Sao aaa Go Pra buG) oc (a t]ocelerelevelacclene selec alecelecsireclese sfeeeleeeleceleceleceleeeleeeleccleve! & lene] ke | me leet] He) & * ioe | # |e |
TET ttt e lew ele eel e wale e a) fee slo eels rela e else cio elersievelersieee itt elearsieneisesisealeseleealeseiessieseieue soolldod seeleeeleneleeeieee! & lessees
. . . 5 . . ° . ° . .
ok © KH EE HE © % % *
Belew ele else elec elev elec els selene sleeeleue elec elewcleealerelareleceleealereleseierelereleesleee! leveleesieeeleaniee aliens! & leweeee sesleee ie: se elew sleet lew elon alee eleesleceleeelecaleeslecelecelecelerslsccieselereleseleselecrleseleee| & lucclerelane He lees taal ists =] ek] #)] & ieee Belew alec elac alan ales eleneleselsssleecleseleselecslsceleeciercleeslersleseleceieeeieesiesrelers| & love! leeeleee! & leweleeeleee) & |) me |e |e ? fe Beles elee ele wale neler eles ele sales slesalecelecclecelenelerelerelerelsesleceleceieseleselsee| oe leeeleselecaleesisesleeeleeeleraleee) ee | e | x laws
Pelee eles ele we ele er sieeve iee elem site elise sion . eeleweleeaisee ales eles eisee * eee eelee el ee ele ew ee ele e ele selene else eleee seeisnn et saclhoo eee
eelew ole ew tlew ele ele sleetieve ee ee eeleeeleesieselieeeieeeieesisee * * ee elee eles eile sole et eiee alee sions * eee ee ele ee eee wee * ore Peele eles ele elec elec slew elaceleeslerelecelecelecclecaierel(escieceleselene oe] fen ele ne) ae [eee lenelerelenelerelecelenelerelsseleseleesleseleselene ” wale welew sles eleraleeeles eis else els eelereleesiere(tesi(erclesaleevlorsieeeiseciee elec] Be fee eleseleeeiene) & lan # lees] ¥ jeee Ke lese
Belew slew slew ele rele eeleeelenelerelenalessleccleesisesleseieesisseleesiseslesales elec elec elon olor elec! e lee eleralerelerelecvions eee Belew alee alee ele neler elev elecaleeslerslecelere|esci(esalessi(oesiescleeeleas|seclos elec eleselecelereleoe| | se le alee oleecleesiene eee selec les slew elem nler elec eles aleeelecalerelerelecelencleralessleseleeslsssianeieeeisealeralerslenciereleesieee, of leweleeeitreleetleeeieanleeciane
Peele wala ew elee elon cle ler clenelenclevelerelerelaccl(eecl(ecelecelsccleeeierelevel(essioesi(sceleselerelersieselaselereiece Pboslecdl bacisce He lecelece wtlewalanclerelen eles cloeelenalaesieealerelecciessioveleccieecleneieeslese| [easier olerslerelees| lerelees eeslevaleseleraieeeiees) ge leucine Jorelenelees Pelee ele wc lee elec elee elec clare lee elenelecaleselecalecelecclerclesclenelocsieralecniencieralecsieveiessieeclecelese| se | ce [ee eleeelenclace Pelee eles alee eleealensleeeleeelavalecelees(eselensleceleceleccleselecsiovelesclscelecelereleseleee| ot | ke leeeleteleeelaceleeeieecleneieee| & ieee! & sete nele neler slew alee sleeelasalerelerelevclecelecclersleve(seeleeelerelesslsrclevciereierelerelane| & leeeleeslereleveleseiersievelese| & | ee lene
Belew alan claw cleeelee slew elecel[ecelerelscelen cles slecelecslsccleeelere(erelnee| & leealeeeierelereleselensiaesisesieetisenineesetieneiees| leeelene sealer alee elec eleealeneler sles nlee clon slecclensiescieesleesi|erelereleeviecslecsloesi(sevisvcleselereleesienaltesisesleneleselsceieeslersiereiasalene
se eleweleceleeslenslenclece slew elecelerelevelecel(ecelerelerelecclessiecslecsleselecsiseci(sesi(sscieseiseeles jeoaleesiscslsesisecisesisssiece Bisialewe|acelaseleselres|ocalmaclocslecc(osclocelore! & lewclocnlecc(acst(soclerclecelecclens(scalesslecelenelasclecclecaleneleeclenslooclece| we
Belew elec elec elec ale alee elenclerelevclesci[ercloeviene| & leeslecslees[eselereierslavelensievsiseceieseie-sleesleosleraisselarsiens ele eelecslece slew alee elewelenalee elec slerslsesieesleecleeeleneisesleesisvciesslesclerelescleralscciene| & sleeeleeelerelene| ge leeeleeeleesleoe| | & lowe Teele w elec alee alec elereleneleceleneles leeelecele salar slecelecslereleeslecelenelerelenelerslereisecleceleveleee| H laselecsleceieealeselecslesslesslece
EIS"
*
96 Tue Lower Cretaceous Deposits oF MARYLAND
THE GEOLOGIC PROVINCE
The Maryland Lower Cretaceous formations constitute part of a belt of deposits of that age extending from Pennsylvania to eastern Alabama. They are apparently embraced within the confines of a single geologic province, although in places transgressed by strata of Upper Cretaceous, Tertiary and Quaternary age.
The Maryland deposits afford the most complete sequence of Lower Cretaceous strata within this district. Three formations are here recog- nized, each with clearly defined lithologic characters, but separable like- wise by easily recognizable unconformities.
Characteristic plant fossils have been found both in Maryland and Virginia, but are unknown elsewhere, although fragmentary plant re- mains’ are known to occur in the Alabama deposits, the Lower Cre- taceous age of which has been recognized by Berry, although the mate- rial thus far collected is too poorly preserved for specific determination or exact correlation with other floras.
To the northward of Maryland the Arundel and Patuxent formations are gradually transgressed by the unconformably overlying Patapsco formation, which in turn gradually disappears by the overlapping ef the Raritan formation in western New Jersey and eastern Pennsylvania, except at a few localities to the west of the city of Philadelphia, where outliers of the Patapsco formation have been found with distinctive lith- ologic characters.
Southward‘in Virginia the Patapsco formation disappears near Fred- ericksburg, except for a single outcrop of this age in the James River valley near City Point. The Arundel formation is not known to occur south of the Potomac River. With the single exception above noted, the Patuxent formation is the only one exposed in south central and southern Virginia, where in the valley of the James River some of the most fos- siliferous beds of this formation have been found. Although they are
separated at the surface from the deposits of the same formation farther
1 Collected by Dr. L. W. Stephenson. ? Philadelphia Folio, U. S. Geological Survey, p. 9, 1909.
MARYLAND GEOLOGICAL SURVEY 97
north through the transgression of younger formations, the continuity of the beds is assumed from the similarity of the flora with its many identi- cal species, as well as from the characteristic lithology.
Deposits formerly called by the name of the Cape Fear formation, but evidently a continuation southward of the Patuxent formation of Vir- ginia, are found in North Carolina. Here again the transgression of the Tertiary and the Quaternary formations interferes with the con- tinuity of the outcrop, although there is no reason to doubt that the deposits are continuous beneath the later strata. No fossils have thus far been discovered in the deposits of North Carolina, but the strata occupy the same stratigraphic position here at the base of the Coastal Plain series as farther north, and are unconformably overlain by Upper Cretaceous formations. The deposits are also strikingly similar to those of the Patuxent formation in Virginia and Maryland, and it seems to be a reasonable assumption that they constitute part of the same formation. :
To the south of North Carolina similar deposits have been long known to extend through South Carolina and Georgia into eastern Alabama.’ The more southern occurrences have been erroneously associated with the Tuscaloosa deposits farther westward in Alabama and Mississippi, from which, however, they are entirely distinct, both in stratigraphic position and lithologic character, while they are separable everywhere by marked unconformities from the overlying Upper Cretaceous deposits, as shown by the broader structural relations of the district. They are unquestion- ably to be associated with the Patuxent beds farther north whether the same formational name is employed throughout the entire district or not. Notwithstanding the evidence in favor of a single formational unit being found at the base of the Coastal Plain series all the way from Maryland to Alabama, it must be admitted that a transgressing sea
1Dr. L. W. Stephenson and Mr. H. W. Berry under the direction of Dr. T. Wayland Vaughan, have greatly enlarged our knowledge of the stratigraphy and paleontology of the South Atlantic and Gulf States, and the results of their work have been available for the comparisons with the southern district south of North Carolina.
EES Scr 98 Tuer Lower Cretaceous Deposits oF MARYLAND
throughout so extended a coast line may well involve considerable time for its accomplishment, and if the transgression proceeded from the north toward the south, as seems probable, the deposits in Alabama would necessarily be somewhat younger than those in Virginia and Maryland.
The differential movements to which the Coastal Plain has every- where been subjected may readily cause, through transgression or inter- formational denudation, a greater or smaller portion of an earlier forma- tion to be exposed along the line of outcrop. It must not therefore be’ assumed that deposits at every outcrop show exact equivalency ; in fact, the basal strata of the Patuxent formation in central Virginia affords evidence of older floral elements than the deposits elsewhere. It may well be therefore that portions of the more southern strata are younger than the more northern beds of this widely extended formational unit.
A much more extended study of Lower Cretaceous deposits in the south may reveal a larger assemblage of organic remains than has hitherto been found. ‘The animal remains are practically limited to the Arundel formation in Maryland, while an extensive flora characterizes the Patuxent and Patapsco in both Maryland and Virginia. A discovery of similar floras elsewhere within the province, both in the northern and the southern districts, would add ees in the final elucidation of the problems presented.
The following table presents in tentative form the correlation of the Lower Cretaceous deposits throughout the Atlantic Coastal plain.
Pennsylvania North South Georgia
an Maryland Virginia 7 : and Delaware CRUE GEES. Eastern Alabama Patapsco ..... Patapsco..... PataPSCO ....| 2.0022 cee ee eee [ene ee ee eeee eee ? SR eee G TSS oes Nun elf ac onecee oe hee aes ee ees een EOE Cretaceous ; ‘** Tuscaloosa” in shad oygaTebe seas Patuxent....| Patuxent....| Patuxent....| Patuxent.... part ?
THE LOWER CRETACEOUS FLORAS OP THE WORED
BY EDWARD W. BERRY
INTRODUCTORY
The Lower Cretaceous, because of the thickness of its deposits, the time interval which it embraces, and the resulting change in plant and animal life, has been considered by certain American geologists to con- stitute one of the major divisions of the geological column under the name Comanchean, although the utility of this term and its ultimate survival is doubtful. Invertebrate paleontologists have taken the lead in determining its subdivisions, the main criteria being the succession of the molluscan faunas, among which the Cephalopoda and the aberrant Rudiste, Chamide, etc., are chiefly relied upon.
Since, except for the initial Cretaceous deposits both in this country and abroad, the conditions in the materials preserved from erosion and available for study are mainly those of marine deposition, fossil plants are unrepresented or only partially represented at a large number of levels. Consequently, they occupy a secondary place in the paleontological cor- relation of the Lower Cretaceous as a whole. These floras are, however, of extraordinary interest, since toward the close of the Lower Cretaceous modern types make their appearance in considerable numbers, and it seems probable that the evolution of the angiosperms, the dominant class of the Tertiary and post-Tertiary floras, was accomplished if not inau- gurated during this period.
While the nomenclature of the subdivisions of the Lower Cretaceous
- varies in different countries and with different authors the following of
NN EE _—_—_—_— 100 THe Lower CRETACEOUS FLORAS OF THE WORLD
the last edition of De Lapparent are generally understood and are used in the present discussion : .
ALBIAN “(d'Orbigny 1842))..-- ce (Gault)
Gargasian (Kilian 1887)? { Bedoulian (Toucas 1888)
os) the Urgonian (d’Orbigny
APTIAN (dOrbigny 1842)*..........
1850) and the Rhodanian (Rene- vier 1854)
Hauterivian (Renevier 1874) Valanginian (Desor 1854)
BARREMIAN (Coquand 1861)?.......
NEOCOMIAN (Thurmann 1835)?.....
As a step in the preparation of the chapter on correlation the various Lower Cretaceous floras have been tabulated, and since they present much that is of interest the following abstract seems worthy of publication. No attempt has been made to completely revise authors’ identifications, and a number of minor papers have been omitted. After sketching briefly what is known of these floras a brief analysis is attempted.
The étages Neocomian, Urgonian, Aptian, and Albian we owe largely to the genius of d’Orbigny. Since the massive limestones of the Ur- gonian at Orgon, in the lower valley of the Durance, represent such a local type of sedimentation and fauna, French geologists have advocated the substitution of the term Barremian, from Barréme in the Basses Alpes, for this stage, which is also sometimes made an upper division of the Neocomian.
With regard to the term Wealden which occupies such a prominent place in geological literature it is quite certain that it represents a phase dependent upon the physical conditions accompanying deposition, which obviously may have been inaugurated at slightly different times in differ- ent areas, aud which may have persisted longer in some areas than in others. Its use should therefore be dissociated from the idea of a chronologic unit and restricted, if used at all, to the stratigraphic unit represented by deposits of this type.
*Kilian in Frech, Lethea geognostica, 2 Teil, 3 Band, Kreide, 1 Abt., Paleocretacicum, 1907.
*Subcretaceous (Gumbel 1881), Eocretaceous (De Lapparent) Palzxocre- taceous (Kilian 1907).
a
MARYLAND GEOLOGICAL SuRVEY 101
The discussions of the age of the Wealden rival in volume those of the Rheetic, Hereynian, and Laramie questions. As transitional deposits the Wealden may well be partly of Jurassic age, but of late years it has come to be accepted as a non-marine facies of the Neocomian, since, where it is present, the lowest marine beds of the Neocomian are said to be absent. That the flora (Seward, Ward) and fauna (Smith Woodward, Marsh) are Jurassic in type is not to be wondered at, indeed it would be remarkable if it were otherwise, since Nature knows no units, and boundary lines in conformable deposits are purely utilitarian or academic. This being true, international rather than provincial usage should prevail, and a unified time scale becomes an urgent necessity.
In the recent masterly summary by Emile Haug (Traité, 1910) the Cretaceous is divided into three major divisions—the Ho-, Meso-, and Neocretaceous ; the Hocretaceous corresponding to the original usage of the Neocomian, the Mesocretaceous being made up of the Albian, Ceno- manian and Turonian stages. This treatment has much to commend it, as can be appreciated by an inspection of Haug’s tables of the range of the characteristic fossils. The paleobotanical evidence, while less full, lends considerable support to such an arrangement, which is also in ac- cord with the diastrophic fact that the extensive transgression of the sea which culminated in the Upper Cretaceous was inaugurated in Albian time.
Lower Cretaceous deposits of various ages occupy large areas in South America, Asia, and Australia, and doubtless in time, as a result of more detailed examination, they will vield their quota toward the completion of the records of distribution of the Cretaceous floras.
THe NEOcoMIAN STAGE’ The name we owe in the first instance to Thurmann (1835). It is derived from Neuchatel (Neocomum), the marine beds of this stage being
typically developed in the Swiss area.
1This term is used throughout in the restricted sense as consisting of the étages Valanginian and Hauterivian and not as synonymous or coextensive with Ho- or Paleo-cretaceous.
SPS he Se ee 102 THe LowEeR CRETACEOUS FLORAS OF THE WORLD
The Neocomian marks the culmination of the upper Jurassic emer- gence, and is emphasized by littoral, estuarine and various types of conti- nental deposits, such as the Morrison and Kootanie of the west and the Wealden of Europe. Marine deposits continue uninterruptedly along the Pacific coast of both. North and South America, the Cretaceous fiora being observed for the first time in the upper portion of the Knoxville beds in the former area. The Neocomian sea of Mexico appears not as yet to have reached the international boundary.
Deposits of this age are typically developed in southern Europe and northern Africa. ‘The eastern and southern coasts of Africa were also receiving sediments as well as a large area in southern Asia. LHastern Greenland shows Neocomian deposits, and an arm of the sea extends southward across central Russia (Petchorian). Along the eastern coast of North America the initial transgression of the Cretaceous sea is not recorded in outcropping deposits of a typically marine character until Upper Cretaceous time, those of the Lower Cretaceous lying buried from observation far to the eastward.
Floras in the marine deposits of this stage are scarce and unimportant biologically, although they are of considerable stratigraphic importance if they are of terrestrial origin, in furnishing data for correlation. Often these fossils are impressions of seaweeds or similar indefinite objects.
Switzerland
From the marine beds in the cantons of Berne, Vaud, Appenzell in Switzerland, and Rapatz in Freiberg Heer’ has described the following:
Aulacophycus pedatus Heer Bambusium neocomense Heer Caulerpa Lehmanni Heer
Chondrites serpentinus Heer Chondrites neocomensis Heer Discophorites angustilobus Heer Discophorites Fischeri Heer
Fucoides friburgensis Heer Gyrophyllites Oosteri Heer Gyrophyllites pentamerus Heer Sphaerococcites meyrati Fischer-Ooster Zamites (Dioonites) Kaufmanni Heer
1 Heer, Fl. Foss. Helvetie, vierte abth., 1877.
MARYLAND GEOLOGICAL SURVEY 103
The second is a supposed grass, the last a cycad, and the balance are indefinite fucoidal-like remains.
Portugal
The Lower Cretaceous of Portugal furnishes a nearly complete section largely the result of the stratigraphic and paleontologic studies of Chof- fat. The fossil plants have been elaborated for the most part by the late Marquis Saporta, whose large work appeared in 1894." The only con- siderable previous work on these floras was the valuable contribution by Heer in 1881.’
The Portuguese deposits are of great interest, not only because of the similarity in floral evolution with the Potomac, shown by the contained floras, but also for the reason that they are largely checked by inter- calated marine faunas." Saporta records the following species from Portuguese beds classed as Neocomian. It is needful to point out that this author’s specific lines are finely drawn, resulting in a multiplication of species scarcely warranted by the character of the materials.
Abietites acicularis Sap.
Adiantum aneimicfolium Sap. Adiantum subtilinervium Sap. Alismacites primevus Sap. Bambusium latifolium Heer Brachyphyllum corallinum Heer Brachyphyllum obesum Heer Caulinites atavinus Heer
Caulinites fimbriatus Sap. Cedrelospermites venulosus Sap. Changarniera dubia Sap.
Cheirolepis Choffati Sap. Cladophlebis argutidens Sap. Cladophlebis Browniana (Dunk:) Sew. Cladophlebis derelicta Sap. Cladophlebis Ungeri (Dunker) Ward Cladophlebis fissipennis Sap.
1Saporta, Fl. Foss. Port., Trav. Géol. Port., Lisbon, 1894.
2 Heer, Cont. Fl. Foss. Port., Trav. Géol. Port., Lisbon, 1881.
’Ward has given the historical details and a somewhat elaborate dis- cussion in a review of Saporta’s great work. Science (N. S.) vol. i, 1895, pp. 337-346.
104 THe LoweR CRETACEOUS FLORAS OF THE WORLD
Cladophlebis minor Sap. Cladophlebis minutissima Sap. Cladophiebis sinuatilobula Sap. Cladophlebis subcycadina Sap. Ctenopteris ultima Sap. Cyclopitys Delgadoi Sap. Cyclopteris tenuestriata Heer Dictyopteris anomala Sap. Dictyopteris infracretacica Sap. Dictyopteris tenella Sap. Hauisetites Burchardti Dunk. Frenelopsis leptoclada Sap. Frenelopsis occidentalis Heer Glossozamites brevior Sap. Glossozamites dilaceratus Sap. Glossozamites modestior Sap. Lonchopteris lusitanica Sap. Marattia minor Sap. Matonidium Althausii (Dunker) Ward Microlepia pluripartita Sap. Neuropteridium spinulosum Sap. Neuropteridium torresianum Sap. Oleandridium tenerum Sap. Onychiopsis Mantelli (Brongn.) Sew. Osmunda retinenda Sap. Pagiophyllum Heerianum Sap. Paleocyparis flexuosa Sap. Pecopteris Choffatiana Heer Pecopteris dilacerata Sap. Philebomeris ? falciformis Sap. Phyllites problematicus Sap. Poacites gemellinervis Sap. Poacites paucinervis Sap. Poacites striatifolius Sap. Poacites tenellus Sap. Podozamites ? acutus Sap. Podozamites ellipsoideus Sap. Podozamites linearis Sap. Podozamites oviformis Sap. Pieridoleimma spoliatum Sap. Pteridoleimma tripartitum Sap. Rhizocaulon elongatum Sap. Rhizocaulon vertus Sap. Ruffordia Gepperti (Dunk.) Seward Scleropteris debilior Sap. Sequoia lusitanica Heer
MARYLAND GEOLOGICAL SURVEY 105
Sequoia subulata lusitanica Sap. Sphenolepidium debile Heer Sphenolepis Kurriana (Dunk.) Schenk Sphenolepis Sternbergiana (Dunk.) Schenk Sphenopteris capillaris Sap. Sphenopteris Choffatiana infracretacica Sap. Sphenopteris cuneifida Sap. Sphenopteris debiliformis Sap. Sphenopteris dissectifolia Sap. Sphenopteris dissectiformis Sap. Sphenopteris flabellinervia Sap. Sphenopteris flabellisecta Sap. Sphenopteris ginkgoides Sap. Sphenopteris Gomesiana Heer Sphenopteris lobulifera Sap. Sphenopteris lupulina Heer Sphenopteris plurinervia Heer Sphenopteris pseudolepida Sap. Sphenopteris subtilinervis Sap. Stachypteris minuta Sap.
Thuyites densior Sap.
Thuyites pulchelliformis Sap. Widdringtonites debilis Sap. Widdringtonites pygmeus Sap. Williamsonia minima Sap.
Yuccites fractifolius Sap.
There are 45 species of ferns, 20 species of conifers, and only 9 species of cycads represented. The Williamsonia, Yuccites, Changarniera, and Poacites striatifolius are considered Proangiosperme, and the balance of the species of Poacites, as well as Rhizocaulon, Alismacites, and Caulamtes are classed as Monocotyledone, Phyllites problematicus, and Cedrelospermites are referred to the Dicotyledone with a query.
It may be noted that seven species (one equisetum, four ferns, and two conifers), cosmopolitan Lower Cretaceous types, are present in the Po- tomac flora, while sixteen of the genera are represented in the Maryland- Virginia area.
France
In France the Wealden type of sedimentation is developed according to De Lapparent south of Beauvais in the Pays de Bray (see Kilian)
106 Tur Lower CRETACEOUS FLORAS OF THE WORLD
and in Hainaut. From this area Brongniart* recorded five species of characteristic Lower Cretaceous plants in 1849. These were Lon- chopteris Mantelli, Pachypteris gracilis, Brachyphyllum Gravesu, Za- mites Brongmarti, and Carpolithus Mantelli.
Cornuel * recorded some additions to the flora in 1866 which he ob- tained from beds of Neocomian age in the Paris basin, and Saporta* and others have made minor contributions. The flora as a whole is poorly developed, and has, in a country so rich in Carboniferous, Jurassic, and Tertiary plant beds, attracted but little attention. The following forms have been recorded:
Brachyphyllum Gravesii (Pomel) Brongniart Equisetum Burchardti Dunker (Carpolithus Mantelli) Pinus aspera Cornuel
Pinus gracilis Cornuel *
Pinus elongaia d’Orbigny
Pinus rhombifera Cornuel
Pinus submarginata Cornuel
Protopteris Buvignieri Brongniart °
Sphenopteris Fittoni Seward (Pachypteris gracilis) Sphenopteris Delgadoi Saporta® (possibly same as Fitton) Weichselia reticulata (S. & W.) Ward
Zamites Brongniarti (Mantell) Brongniart
England
The flora of the English Wealden, using that term in the more re- stricted sense for the Hastings beds and the overlying Weald Clay (H. B. Woodward) is of interest not only because its flora is the only European flora outside of Portugal which has been revised in recent years, but
1 Brongniart, Tableau, 1849, pp. 107, 108.
?Cornuel, Des cénes de pins trouves dans les couches fluviolacustres de l’étage- néocomién du bassin parisien, ete. Bull. Soc. géol. Fr. (2e série), tome xxiii, 1866, pp. 658-673, pl. xii. Note sur les céOnes de Pinus elongata découverts a Saint-Dizier (Haute-Marne) et sur des cénes de cédre du sable vert de la Houpette (Meuse), Bull. Soc. géol. Fr. (3e série) tome x, 1882, pp. 259-263.
> Saporta, Notice sur les végét. foss. de la craie infér. des environs du Havre, Mém. Soc. Géol. de Normandie, 1877.
*The name of this species is preoccupied by Saporta’s Tertiary species from Aix in Provence.
5 Brongniart, Tableau, 1849, pp. 35, 111
® Saporta, Rev. gén. bot. tome v, 1893, p. 365, pl. iv, fig. 5.
MARYLAND GEOLOGICAL SURVEY 107
also from the striking similarity in lithology between it and the Potomac beds.
The flora has been elaborated by Seward* who gives an abridged his-
torical sketch of its study in his introduction. The following species are recorded :
Acrostichopteris Ruffordi Sew. Algites catenelloides Seward Algites valdensis Seward Androstrobus Nathorsti Sew. Anomozamites Lyellianus (Dunk.) Becklesia anomala Sew. Bennettites sp.
Bennettites Carruthersi Sew. Bennettites Carruthersi var. latifolius Sew. Bennettites Gibsonianus Carr. ; Bennettites Saxbyanus (Brown) Brachyphyllum obesum Heer Brachyphyllum spinosum Sew. Bucklandia anomala (S. & W.) Carpolithes sp.
Chara Knowltoni Sew. Cladophlebis Albertsii (Dunk.) Cladophlebis Browniana (Dunk.) Cladophlebis Dunkeri (Schimp.) Cladophlebis longipennis Sew. Conites (Araucarites) sp.
Conites armatus Sew.
Cycadites Remeri Schenk. Cycadites Saporte Sew. Cycadolepis
ef. Dichopteris levigata (Phill.) Dictyophyllum Remeri Schenk Dioonites Brongniarti (Mant.) Dioonites Dunkerianus GOpp. Equisetites Burchardti Dunk. EHquisetites Lyelli Mantell Hquisetites Yokoyamne@e Sew. Fittonia Ruffordia Sew. Leckenbya valdensis Sew. Marchantites Zeilleri Sew. Matonidium Althausii (Dunker) Ward Microdictyon Dunkeri (Schenk) ef. Nageiopsis heterophylla Font. Nilsonia schaumburgensis (Dunk.)
1 Seward, Wealden Flora, pt. i, 1894; pt. ii, 1895.
108 Tur Lower CRETACEOUS FLoRAS OF THE WORLD
Onychiopsis Mantelli (Brongn.) Onychiopsis elongata (Geyler) Otozamites Geppertianus (Dunk.) Otozamites Klipsteinii (Dunk.) Otozamites Klipsteinii superbus Sew. Otozamites Klipsteinii longifolius Sew. Otozamites sp., cf. O. Reibeiroanus Heer Pagiophyllum crassifolium (Schenk) Pagiophyllum sp.
Pinites Carruthersi Gard.
Pinites Dunkeri Carr.
Pinites Ruffordi Sew.
Pinites Solmsii Sew.
Protopteris Witteana Schenk
Ruffordia Gopperti (Dunk.)
Ruffordia Gopperti var. latifolia Sew. Sagenopteris acutifolia Sew. Sagenopteris Mantel (Dunk.) Schenk Sphenolepis Kurriana (Dunk.) Schenk Sphenolepis Sternbergiana (Dunk.) Schenk cf. Sphenolepidium (Sequoia) subulatum Heer Sphenolepidium sp.
Sphenopteris Fittoni Sew.
Sphenopteris Fontainei Sew. Teniopteris Beyrichii (Schenk) Teniopteris Beyrichii var. superba Sew. Teniopteris Dawsoni Sew.
Tempskya Schimperi Corda
Thuites valdensis Sew.
Weichselia reticulata (S. & W.) Ward Withamia Saporte Sew.
Yatesia Morrisw Carr.
Zamites Buchianus (Htt.)
Zamites Carruthersi Sew. -
Zamites Carruthersi var. latifolius Sew.
These include 2 alge, 1 chara, 1 bryophyte, 3 equiseta, 23 ferns, 16 conifers, and 24 cycadophytes. ‘Twelve of the widespread species are present in the Potomac flora. There are 16 common genera represented in the two areas and a number of distinct, but closely related species in the two floras.
Belgium
Dumont divided the Aachenian of Hainaut into an upper and a lower
stage, but in recent years Belgian geologists have restricted Dumont’s
MARYLAND GEOLOGICAL SURVEY 109
term to the Upper Cretaceous of Aix-la-Chapelle, and have proposed the term Bernissartian (Purves, 1883) for the Lower Cretaceous, which is often spoken of as Wealden and was formerly considered the age of the Gault. That both these horizons, as well as several intermediate ones, are present in this area is not at all improbable. The floras have been studied by Cocmans, Saporta, and more recently by Seward.’ Pro- fessor Bommer is engaged at the present time in studying well-preserved plant material of this age from near Brussels.’ A list of the recorded species includes the following :
Adiantites sp., Seward
Algites sp.. Seward
Cedrus corneti Coemans
Cladophlebis Ungeri (Durker) Ward Cladophlebis Browniana (Dunker) Seward Conites minuta Seward
Cycadeoidea (Cycadites) Schachti (Coemans) Equisetites ? sp., Seward
Gleichenia ? (in fruit) Saporta
Gleichenites sp., Seward
Leaccopteris Dunkeri Schenk
Leckenbya. valdensis Seward
Lycopodites sp., Seward
Matonidium Althausii (Dunker) Ward e Onychiopsis psilotoides (Stokes and Webb) Ward Pinites Solmsii Seward
Pinus Andrei Coemans
Pinus Briarti Coemans
Pinus depressa Coemans
Pinus gibbosa Coemans
Pinus Heeri Coemans
Pinus Omalii Coemans
Pinus Toillezi Coemans
+Comans, Fl. foss. du premier étage du terrain crétacé du Hainaut. Mém. Acad. Roy. Belg., tome xxxvi, 1867.
?Dupont, Sur la découverte d’ossements d’Iguancdon, de poissons et de végétaux dans la fosse Sainte-Barbe du charbonage de Bernissart, Bull. Acad. Roy. Belg., (2e série), tome xlvi, 1878, pp. 387-408 (plants determined by Saporta on page 396).
8 Seward, La Flore Wealdienne de Bernissart, Mém. Mus. Roy. d’Hist. Nat. de Belg., Année 1900.
*Bommer, Nouveau gite de végét. découvert dans l’argile Wealdienne de Bracquegnies (Hainaut), Bull. Soc. belge. de:Géol. Paléont. et Hydrol., tome vi, 1892, p. 160.
110 Tue Lower CRETACEOUS FLORAS OF THE WORLD
Protorhipis Remeri Schenk Ruffordia Gepperti (Dunker) Seward Sagenopteris Mantelli (Dunker) Seward Sphenopteris delicatissima Schenk Sphenopteris Fittoni Seward cf. Teniopteris, Seward = Nilsonia (7?) Weichselia reticulata (Stokes and Webb) Ward The Belgium flora is of a very fragmentary character, but apparently includes one or more vague algal remains, 15 or 16 varieties of ferns,
1 lycopod, 1 equisetum, only 1 cycad, and 10 conifers.
Germany
The serious study of the flora of the German Wealden may be said to have begun with Dunker’s oft-quoted monograph, which appeared in 1846. In the German area (northwest Germany, Hanover, and the Hol- land frontier) the Hastings sand of England is represented by the Diester (Hils) sandstone, while the upper or argillaceous member is called the Weald clay (Walderthon). The term Wealden has sometimes been amplified to include the underlying Purbeck, as is the case in Kay- ser’s well-known text-book. Other writers consider the German Wealden older than that of England,’ a view certainly not supported by the flora.
The most important contributor to our knowledge of the German Wealden flora is Schenk, although Ettingshausen and others have made minor contributions. A partially revised list of the recorded species in- cludes the following:
Abietites Linkii (Roemer) Dunker Alethopteris cycadina Schenk
Alethopteris Huttoni (Dunker) Anomozamites Schaumburgense (Dunker) Baiera pluripartita Schimper
Cladophlebis Browniana (Dunker) Seward Cladophlebis Ungeri (Dunker) Ward Clathraria Lyell Stokes and Webb
1Pavlow and Lamplugh, Argiles de Speeton et leurs équivalents. Moscou, 1892.
2? Schenk, Die Flora der nordwestdeutschen Wealdenformation, Palaeonto- graphica, Band xix, 1871, pp. 203-276, pl. xxii-xliii; Band xxiii, 1876, pp. 157- 163, pl. xxv, Xxvi.
MARYLAND GEOLOGICAL SURVEY j11
Cycadites Remeri Schenk
Dioonites Dunkerianus (Goeppert)
Dioonites Geppertianus (Dunker) Equisetum Burchardti Dunker
Hausmannia dichotoma Dunker
Jeanpaulia Brauniana Dunker
Lomatopteris Schimperi Schenk
Marsilidium speciosum Schenk
Matonidium Althausi (Dunker) Ward Microdictyon (Laccopteris) Dunkeri (Schenk) Onychiopsis psilotoides (Stokes and Webb) Ward Pachyphyllum curvifolium (Dunker) Schenk Pachyphyllum crassifolium Schenk Pecopteris Murchisoni Dunker
Protopteris Witteana Schenk
Pterophyllum Lyellianum Dunker
Ruffordia Gepperti (Dunker) Seward Sagenopteris Mantelli (Dunker)
Sphenolepis Kurriana (Dunker) Schenk Sphenolepis Sternbergiana (Dunker) Schenk Spirangium Jugleri (EHttings) Schenk (probably not a plant) Sphenopteris delicatissima Schenk Sphenopteris adiantifrons Ettingshausen Sphenopteris Fittoni Seward
Tempskya Schimperi Corda
The ferns are largely in the majority in this list, numbering 18 species, while the conifers furnish but 7 species and the cycads 6 species.
From the neighboring area of Westphalia Hosius and von der Marck* have described the following species, which they designate as Neocomian:
Abietites Linkii (Roemer) Dunker
Dioonites abietinus Miquel
Laccopteris Dunkeri Schenk
Lonchopteris recentior Schenk
Pinus Quenstedti Heer ?
Pitcairnia primeva Hosius and Von der Marck Podozamites equalis Miquel
Protopteris punctata Sternberg
Pierophyllum blechniforme Hosius and Von der Marck Pierophyllum Germari H. v. Otto
Pierophyllum saxonicum Reich ?
Sagenopteris neocomiensis Hosius and Von der Marck
1Hosius and Von der Marck, Die Flora der westfalischen Kreideformation,
Palaeontographica, Band xxvi, 1880, pp. 80-95; Nachtrag, Band xxxi, 1885, p. 231. 8
12 Tuer Lower CRETACEOUS FLORAS OF THE WORLD
Sphenolepis Kurriana (Dunker) Schenk
Sphenolepis Sternbergiana (Dunker) Schenk
Weichselia reticulata (Stokes and Webb) Ward (Ludovice Stiehler) Zamites iburgensis Hosius and Von der Marck
Zamites nervosus Schenk
Saxony
The Neocomian sandstones of Langenberg, near Quedlinburg. of Wester- hausen, etc., in Saxony, formerly considered of Quader age, have fur- nished a considerable flora, Stiehler * having described three species from this region as long ago as 1858. Schulze,’ in 1888, added considerably to the list of plants, and more recently Richter * has been elaborating this flora in a most careful manner. He follows von Koenen in correlating the Wealden with the Berriasian below the ammonite zones of the Valan- ginian and Hauterivian. A partially revised list of the recorded species is as follows:
Alethopteris cycadina Schenk
Alethopteris revoluta Schenk
Baiera miinsteriana (Presl) Heer (obviously an incorrect identification of * this Rhetic species)
Cylindrites spongioides Goeppert
Gleichenia cf. giesekiana Heer
Gleichenia longipennis Heer
Gleichenia cf. rotula Heer |
Glossozamites Schenkii Heer
Hausmannia dichotoma Dunker
Hausmannia gracillima Richter
Hausmannia Kohlmanni Richter
Hausmannia Sewardi Richter
Hausmannia spuria Richter
1Stiehler, Die Flora des Langeberges bei Quedlinburg, Palaeontographica, Band v, 1855-1858, pp. 71-80, pl. xii-xv.
2 Schulze, Ueber die Flora der subhercynschen Kreide, Zeits. gesammt. Naturw. Halle, Band Ix, 1887, pp. 440-470.
* Richter, Neocompflanzen der Kelb’schen Sandgrube bei Quedlinburg, Zeits. deutsch. geol. Gesell., Band li, 1899, Verhandlungen, pp. 39-41. Beitr. z. Flora der unteren Kreide Quedlinburgs. Teil i. Die Gattung Hausmannia Dunker und einige seltenere Pflanzenreste. Leipzig, 1906, pp. 27, pls. 7. Teil ii. Die Gattung Nathorstiana P. Richter und Cylindrites spongioides Goeppert. Leipzig, 1909, pp. 12, pl. 6. Cylindrites spongioides Goeppert und Nathorstiana P. Richter, Monatsber. Deutsch. Geol. Gesell., Band ~<1xii, 1910, pp. 278-284.
MARYLAND GEOLOGICAL SuRVEY 113
Matonidium Althausii (Dunker) Ward
Microdictyon regale Richter (= Laccopteris ?)
Moriconia cyclotoron Debey and Ettings. (obviously a wrong identification of this Upper Cretaceous species)
Nathorstiana arborea Richter
Nathorstiana gracilis Richter
Nathorstiana squamosa Richter
Onychiopsis psilotoides (Stokes and Webb) Ward
Pandanus Simild@ Stiehler
Phlebopteris dubia Richter (= Laccopteris)
Pterophyllum Ernestine Stiehler
Pteridophyllum fastigiatum Schulze
Schizoneuropsis posthuma Richter
Sphenolepis Kurriana (Dunker) Schenk (imbricata Roemer)
Nphenolepis Sternbergiana (Dunker) Schenk (cf. Sequoia falcifolia Schulze)
Weichselia reticulata (Stokes and Webb) Ward (Ludovice Stiehler)
Zamites speciosus Heer i
Zamites sp., Schulze
This flora is remarkable for the large number of ferns which it con- tains, the genus Hausmannia of the Dipteriacew being especially well represented.
Sweden
Nathorst, as quoted by ‘Seward in his Wealden flora, is the authority for the statement that Lower Cretaceous floras are absent from the Seandinavian region.
Africa
The Uitenhage series of South Africa is often referred to the Upper Jurassic. Fossil plants were recorded from these rocks by Tate* many years ago, and more recently Seward has revised* and added to* the flora. The latter author considers these beds as of approximately the same age as the English Wealden. The following species are recorded:
Araucarites rogersi Seward Benstedtia sp., Seward * Brachyphyllum sp., Seward &
‘Tate, On the Secondary Fossils from South Africa, Quart. Journ. Geol. Soe. Lond., vol. xxiii, 1867, pp. 139-175, pls. v-ix.
? Seward, Ann. S. Afr. Mus., vol. iv, 1903, pp. 1-46, pls.
*Seward, Notes on Fossil Plants from South Africa, Geol. Mag., Dec. vy, vol. iv, 1907, pp. 481-487, pls. xx, xxi.
*Stopes has recently shown that these supposed cycad remains are conifers.
114. Tne LowER CRETACEOUS F'LORAS OF THE WORLD
Bucklandia sp., cf. anomala Carruthers Carpolithus sp., Seward
Conites sp., A, sp., B
Cladophlebis Browniana (Dunker) Seward Cladophlebis denticulata forma atherstonei Seward Cycadolepis Jenkinsiana (Tate) Seward
Nilsonia Tatei Seward
Onychiopsis psilotoides (Stokes and Webb) Ward Osmundites Kolbei Seward *
Phyllotheca Whaitsi Seward
Sphenopteris Fittoni Seward
Sphenopteris sp., Seward
Teniopteris sp., cf. arctica Heer
Taxites sp., Seward
Zamites africana (Tate) Seward
Zamites Morrisui (Tate) Seward
Zamites recta (Tate) Seward
Zamites rubidgei (Tate) Seward
New Zealand
The two species, Polypodium [Hochstetterr Unger, and Sphenopteris Fittoni Seward, have been recorded from New Zealand beds which have been tentatively correlated with the Wealden by Seward.
Peru
The explorations of Professor Steinmann in Peru during 1903-1904 resulted in the discovery of Neocomian plants at