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DEPARTMENT OF CONSERVATION AND ECONOMIC DEVELOPMENT DIVISION OF MINERAL RESOURCES Box 3667, University Station Charlottesville, Virginia Jarnes L. Calver, Cornrnissioner of Mineral Resources and State Geoloeist
Inforrnation Circular 6
GUiDEBOOK to THE COASTAL PLAIN OF VIRGINIA NORTH OF THE JAMES RIVER
Charlottesville, Virginia 19 62 ERRATA trnforrnation Circular 6
Page vi', ?t , o. Fredricksburg,. " should read, ". Fredericksburg,. " and., " Potornic should read, " . Potornac. " . Page 4, in caption: ... Forrnati.on, " " sholrJ.d read" ". forrnations",, Page 15, Clark and MiLler (l9llj: should read. Tur::itel1a" Turitella... " " " " Page I8; Turn Left on U, S" Highway 360 at Wansaw. " " should read" ", Turn right on U. S. Highway 360 at Warsaw, " " Page t'one l9: Turn right onrrone way" dirt road." " " shouLd read". " Turn right or., park road to battl.efield" ,way'r " " Page 21: Proceed onrrone way" dirt road and turn right on State Highway 238". " should read. ". Proceed on "one way" park road and turn right on State Highway 23B" . .
Page ZZ; .. ' Straight ahead on State Road l00l at intersection of State Highway 238 and State Road 1001 (about one block) ".. should read". " Stay on State Highway 238 past the entrance of Vi.sitor Center of Yorktown Battlefield to the inter- section with State Road 1001" " . . Turn right on U. S" Highway L7 and cz'osc George P" Colernan Mernori.al Bridge" ". should read... Strai.ght ahead orr State Road 1001 for approxirnately Z blocks and turn right on U. S" Flighway l? to cross George P. Colernan Memorial Bridge. , .
Page 23: (mileage) "..7.7 ?1.6 (accurnu}ative rnitreage)" " " should read ...9"4 73,3, . " and suce eeding accurnulative rnileages
" siroulf read ". . .". . . "i:""2. "it"?. " ,."74,7"." " "."7tr^4""" .75"1""" " "".76.9.. "75"4."" " ,""77.1"". Page 25: (accurnulative rnileage) "..77.6 , ". should read " " " 79" 3.. " "."79'0"." " ,""80"? "".187.". ,, lgg.". Page 26, line 14: laterally in }ayers" should read", lateraLly layers" " " " into " " Page 44, Clark, w. 8., l9l0: ". " Arnerican. " " shor.lLd read"." Arnerica"..
Virginia Division of Mineral Resources CharlottesviLle, Virginia DEPARTMENT OF. CONSERVATION AND ECONOMIC DEVELOPMENT DIVISION OF MINERAL RESOURCES Box 3667, University Station Charlottesville, Virginia Jarnes L. Calver, Cornrnissioner of Mineral Resources and State Geologist
Inforrnation Circular 6
GUIDEBOOK to THE COASTAL PLAIN OF VIRGINIA NORTH OF THE JAMES RIVER
This guidebook was prepared under the general direction of Jarnes L. calver, state Geologist of virginia. The following staff rnernbers of the Virginia Division of Mineral Resources who helped in preparation of the guidebook are Jarnes L. Ruhle, cornpilation of text; Robert C. Milici and Bruce Hobbs, editing and field check; Richard H. DeKay, field check; andJohn Wilson, rnap illustrations. Horace G. Richard.s, Associate curator, Acad.erny of Natural sciences of Philadelphia, assisted in the prelirninary planning and in the checking of fossil 1ists.
Charlottesville, Virginia L962 CONTENTS Page
Introduction . I
Geographical setting I Geological setting 3 Historicalsunrrrrary. . 3
Road log and locality descriptions . 7
First day of field conference 7 Second day of field conference. . 19
Stratigraphy. 26
Lower Cretaceous z6 Potornac group 26 Patuxent forrnation. z6 Patapsco forrnation z7
Upper Cretaceous - Paleocene 27 Mattaponi forrnation z7
Paleocene and Eocene z7 Parnunkey group. , z7 Aquia forrnation . . 27 Nanj ernoy f orrnation z8 Upper Eocene . . z9 Chickahorniny f orrnation z9
Miocene )o Chesapeake group . . )o Calvert forrnation . . ?Q Choptank forrnation 30 St. Marys formation . . 30 Yorktown forrnation 31
Plio - Pleistocene .
List of fossils . 33
Patr:xent forrnation 33 Patapsco forrnation 33 Aquia forrnation 34 Nanj ernoy f orrnation 37 Calvert forrnation 38 Choptank forrnation 39 St. Marys forrnation 40 Yorktown forrnation 40
References FIGURES Page
l. Index rnap of localities and route . . vi'
z. Generalized geologic rrrap of the Coastal Plain of Virginia. z
3. Arkosic sands of the Patuxent forrnation T
4. Cross-bedded sands with clay balls and lenses which occur in the Patuxent forrnation 9
5. Variegated clay strata of the Patapsco forrnation. . l0 6. Fossiliferous layers in the Aquia forrnation . . ll
7. Blocks of calcareous sandstone f rorn the Aquia formation containing casts and rnolds of Turritella rnortoni 13
8. Argillaceous greensand of the Nanjernoy forrnation 14
9. Diatornaceous clavs of the Calvert forrnation L7 i0. Fossiliferous beds and cross-bedded strata of the Yorktown forrnation Z0
I l. Shell rnarl of the Yorktown forrnation . . Zl lZ. Isognornon rnaxillatum zone in the St. Marys forrnation . . ZZ t3. Fossiliferous argillaceous sand and silt strata of the St. Marys forrnation z4
TABLES
l. Correlation chart of Cretaceous and Tertiary forrnations in Virginia with those of the Northern Atlantic and Gulf Coasts . .
z. Chronological development of nalnes applied to geologic units in the Coastal Plain of Virginia EXPLANATION l. Chary Hill: 7. British Redoubt No'lO: Potuxent formotion Yorktown'formotion 2. Possum Poini: 8. Moore House: Poiopsco formotion Yorktown formolion WASHINGTON 3. Belvidere Beoch: 9. Corbin Creekl Aquio St. Morys formofion ALEXANDRIA formoiion lO. Neor BowlersWhorf : at 4. Foirview Beoch: t/. Aquio formolion St Morys formofion ./? 5. Woodslock: Non jemoy formotion 6. Slrotford Cliffs: Colvert , ChoPtonk, ond Sl. Morys formolions
i-j -\
t t
Figure l. Mop of locolities ond route GUIDEBOOK TO THE COASTAL PLAIN OF VIRGINIA NORTH OF THE JAMES RIVER
by Jarnes L. Ruhle
TNTRODUCTION
Geologic formations of the Coastal Plain have been described in the literature for ap- proxirnately I50 years. In order to meet the dernand for a guide to the farnous localities at which these forrnations rnay be seen and studied, this publication was prepared. The first use of this inforrnation as a guidebook was rnade in October 1952 during the Third Annual Fietd
Conference of the Atlantic Coastal Plain Geological Association. Localities include Lower.
Cretaceous, Eocene, and Miocene strata and were selected because either they are I'type 1o- calitiestr or they contain material which is representative of the forrnations in the Coastal Plain
(Figure 1).
GEOGRAPHICAL SETTING
The Coastal Plain province of Virginia consists of a gently sloping lowland that has a
rnaximurn elevation of slightly over 400 feet in rolling hills along the Fall Zone. The Fall Zone
extends southwestward frorn Washington along a line through Fredericksburg and thence south-
ward through Richrnond, Petersburg, and Ernporia. The Virginia portion of the Coastal Plain
province has an area of approxirnately 10,000 square miles, which constitutes about 25 percent
of the area of the Cornrnonwealth, and has an average east-west width of about 100 rniles. Be-
tween the Fall Zone and the Chesapeake Bay, the area is bounded on the north by the Potomac
River and is divided southward by ttre Rappahannock, York, and Jarnes rivers. The Potornac
and Jarnes rivers (Trans-Blue Ridge types) have their headwaters in the Appalachian Plateau
and the Ridge and Valley provinces. The Rappahannock and York rivers, (Piedrnont types),
have their headwaters rnainly in the Piedrnont province. Srnaller rivers, such as the Piankatank
and Great Wicomico (Coastal Plain types), have their headwaters originating in the Coastal
Plain province. EXPLANATION
(hotenny Eocene lo"g'l Sona ond grovel EE| Nonjemoy fomolion Alerondrio Miocene E7o? aquio formolion E fr" **" formolion creloceous ffi.l st Morys formorion H ffiilm Poloosco formotion 1,191 | Chopfonk formofion -- - - Potuxenf formolion - .-' .- lhg l-r-i. :ll Gdvrt formotion u =
Gelogy conpated froh t9Z8 srot. Estogic mop ^ .- s6tr lJ
Richmond
Figure 2. Generolized geologic mop of the Coostol Ploin of Virginio 3
The subrnerged portion of the Coastal Plain, the Continental Shelf, continues frorn the
Virginia shoreline for approxirnately 65 rniles, and has an area of approxirnately 5000 sqrErre rniles. The surface generally is a broad plain sloping gently seaward, although it is decidedly undulatory near shore. These undulations forrn elliptical shoals with their long diarneters parallel to the shoreline. Two subrnarine canyons, the l'Vashington and the Norfolk, occur as notches in the shelf.
GEOLOGICAL SETTING
Forrnations exposed in the Coastal Plain of Virginia are of Lower Cretaceous, Eocene,
Miocene, Pliocene, and Pleistocene ages (Figure Z). They strike approxirnately parallel to the
Fall Zone, and have a rnonoclinal easterly dip which changes frorn 50 feet a rnile in the older deposits to less than 5 feet a rnile in the younger deposits.
The Coastal Plain sedirnents have been deposited on igneous and rnetarnorphic rocks
(crystalline rocks) and Triassic (?) sedirnents. Along the Fall Zone the deposits are relative- ly thin; erosional outliers of Lower Cretaceous and Tertiary forrnations occur west of the rnain outcrop. The thickness of the sediments progressively increases eastward. At Mathews,
Mathews County, a well encountered crystalline rocks at a depth of Z32O feet; a well at Fort
Monroe, 25 rniles south of Mathews, reached these rocks at ?246 f.eet. Other wells have pene- trated Upper Cretaceous, Paleocene, and Upper Eocene (Jackson age) units that are overlapped by younger sedirnents and are not exposed at the surface. The succession of forrnations of the
Coastal Plain of Virginia, and a tentative correlation with New Jersey and Gulf Coast equiva- lents, is given in Table l.
Geophysical investigations (Ewing, Crary, and Rutherford, 1937) carried out across the
Continental Shelf indicate that the depth to crystalline rocks is over lZ,0O0 feetjust off Cape
Henry. A seisrnic discontinuity between supposedly consolidated Triassic-Jurassic sedirnents and serni-consolidated Cretaceous and younger sedirnents shows a reversal in dip between l0 and 60 rniles off Cape Henry.
HISTORICAL SUMMARY
The geological literature of the Coastal Plain of Virginia, which spans a period of nearly two centuries, includes about a thousand references. The earliest reference contains a Table l. Correlation chart of Cretaceous and Tertiary Formation in Virgin5.a with those of the Northern Atlantic and Gulf coasts
NEW JERSEY DELAWARE MARYLAND VIRGINIA GULF
Brandywine Upland gravels Pl iocene Beacon Hill Bryn Mawr (?) and sands Gol i ad /l^ Bryn Mawr \ rrr Por^--+\ L / Cohansey tr tr Pa s cag oul a c|t o o Chesapeake Yorktown -vo o Miocene 9roup o St. Marys o St. Marys Hattie sburg Kirkwood tunolfrer- o Choptank o Choptank @ o entiated ) o Calvert o Calvert Catahoula
ttJa cksontt Piney Point (?) Piney Point Chickahominy Jackson ( subsurface ) ( subsurface ) ( subsur fa ce ) Eocene Shark River t{ h Cl a iborne Mana squan unnamed c'l Narr j emoy ct)
Vincentown sediments o, o .!. ll Wi I cox C E E r' o 6 n x I I t I Pa I eo cene o -^l-1,,llo !r rr y Brightseat Midway w I n subsurface I Mat+ ^ I ',t.ulp.o^ni Tinton I -oCe o tr I ct) Red Bank Red Bank o Navarro Monmouth li Nave si nk o. Upper + E Navesink- o o Mount Laurel Mt. Laurel Cretaceous C = Wenonah Wenonah o oo- Marshal ltown N =aoo Eng I i shtown Matawan Taylor {J t{ c'r' o(t Woodbury o o = Merchantvi I I e Merchantville t{ + Magothy Maoothv Maqothv o Austin t-an Woodbi ne Raritan o ari Raritan P o o. +) o o Lower c )ataps H Patapsco tr Patapsco . o co o) cTr Absent in A Comanche o o outcrop o Arundel @ Cretaceous E latuxent o Patuxent o Patuxent ro P Po o q. 5 geological description of the shell rnarl (Yorktown forrnation) of the York River area (Lincoln,
1783) . Stratigraphic studies, which were rnade at the start ctf the l800rs, contain descriptions of the lithologies of,the Coastal Plain forrnations and were still Wernerian in nature. The works of Tirnothy A. Conrad and Williarn B. Rogers marked the first departure frorn this con- cept. Rogers, the first I'State Geologist" of Virginia (1835-41), and Conrad were arnong the first to lay the foundation for faunal studies of Tertiary forrnations of the Virginia portion of the Coastal Plain using systematic and stratigraphic paleontology. Invertebrate fossils, and
1ater, rnegascopic plant fossils, were used to i.dentify forrnational units, particularly those of the Lower Cretaceous formations. The principal workers in the field of paleobotany include
Williarn M. Fontaine, E. Wilber Berry, Lester F. Ward, and Frank H. Knowlton. About this tirne, geologic rnapping was in progress in the Coastal Plain of Virginia by Nelson H. Darton and W J McGee. Darton wrote several geological folios, and McGee described the distribution of the terrace gravels and the Lower Cretaceous sedirnents. In the early l900ts, William B.
Clark and Benjarnin L. Miller studied the geology of the Coastal Plain. Their I'Physiography and geology in the Coastal Plain province of Virginia,tr which appeaied in l9lZ, is rnuch in use today. In the present century refined rnethods, such as rnicropaleontology, palynology, sedi- rnentary petrology, geophysics, geochernistry, and aerophotography have been used to decifer the geology of the Coastal P1ain of Virginia
Table 2 contains the stratigraphic terrninology that has evolved through the years from the tirne Maclure grouped all rock units under "Alluvial forrnationil to the present time. o P u, L o 4O 3 rUr o h- o t{ ,PE t{. (hc\ X. -vo {J€ QT OE (o9 trd( Eg o.k >(F tr(: '}1$H o ut 4 E. oo {J odC o + € 2 (l)E o o o a.t O (r) O gl o=- O o o|.- C snoace+erc reMo'l a t ql .d o-lr) o os C P d o.o\ z, o P k o\ F{, O. k. ! od o c OE {JE OE fi OF FrO o dPo o-q >q o oo (J
d c) o+ o o+ c) o+ lr .d.Fr .d.rl tr >Eo >Eo >Eo t(ts o, HC 5q o. oc occ C o@ C o- i.d od = = = 7
ROAD LOG AND LOCALITY DESCRIPTIONS
FIRST DAY OF FIELD CONFERENCE Friday, October LZ, L96Z
Departure tirne, 8:00 a. rn. E. D. T. (7:00 a. rn. E. S. T. ) Greyhound Bus Terrninal, Alexandria, Virginia
Mileage Accurnulative Mileage Itine rarY
0.0 0.0 Leave bus terrninal and proceed south frorn North Washington Street to South Washington Street.
0.4 0.4 Turn right on Gibbon Street.
o.z 0.6 Turn left on St. Patrick Street, and proceed south on U. S. Highway l.
16.4 17. 0 On right: Clay pit of the Woodbridge Clay Pro- ducts Cornpany. Quantico slate (Ordo- vician?) and clay are obtained frorn this pit for the rnanufacture of brick and tile.
4.0 21. 0 On left: Outcrop of cross-bedded sands of the Patuxent f orrnation.
3.2 24. z Turn left on State Road 635 at Texaco Station.
3.6 27.8 Turn left on dirt road just before railroad cros- sing .
0. 3 28. L STOP I: PATUXENT FORMATION - RAILROAD CUT NEAR CHERRY HILL (l hour and I 5 rninute s)
Walk north along the railroad tracks. The Pa- tuxent forrnation crops out for nearly half a rnile along the railroad. The lithology is varied in both horizontal and vertical directions.
Figure 3. Arkosic sands of the Pattrxent forrnation 7
ROAD LOG AND LOCALITY DESCRIPTIONS
FIRST DAY OF FIELD CONFERENCE Fridav, October lZ, l962
Departure tirne, 8:00 a. rn. E. D. T. (7:00 a. rn. E. S. T. ) Greyhound Bus Terrninal, Alexandria, Virginia
Accurnulative Mileage Itine rarY
0.0 Leave bus terrninal and proceed south frorn North Washington Street to South Washington Street.
0.4 0.4 Turn right on Gibbon Street.
o.z u.b Turn left on St. Patrick Street, and proceed south on U. S. Highway l. r6.4 17. 0 On right: CIay pit of the Woodbridge Clay Pro- ducts Cornpany. Quantico slate (Ordo- vician?) and clay are obtained frorn this pit for the rnanufacture of brick and ti 1e.
+.u zt. o On left: Outcrop of cross-bedded sands of the Patr,rxent f orrnation .
3.2 24. z Turn left on State Road 635 at Texaco Station.
27.8 Turn left on dirt road just before railroad cros- slng.
0. 3 28. L STOP I: PATUXENT FORMATION . RAILROAD CUT NEAR CHERRY HILL (l hour and I 5 rninutes)
Walk north along the railroad tracks. The Pa- tuxent forrnation crops out for nearly half a rnile along the railroad. The lithology is varied in both horizontal and vertical directions.
il:t:4 ;t;:
Figure 3. Arkosic sands of the Patuxent forrnation 8
The following section was tyreasured at the so.uthern end of the outcroP, on the west face of the cut.
Thickne s s Description
PLEISTOCENE 15' Gravel and loarn, gray-brown, sandY
0. 51 Sandstone, red-brown, lirnonitic
PATUXENT FORMATION 15' Sand, gray, rnedirrrn-grained, arkosic, cross-bedded, containing pebbles, and thin clay larninae
0.5t Sandstone, red-brown, lirnonitic
Zt Clay, gray' very Plastic LZt Sand, graY to white, rnediurn- to coarse-grained, arkosic, cross- bedded
It Sandstone, red-brown, lirnonitic I0' CLay, gray-green, cornPact, siltY, rnicaceous
4.51 Sand, red-brown, rnedium to fine- grained, silty
4l Clay, gray-green, cornPact, larninated, silty, rnicaceous
2.5' Sand, red-brown, fine-grained, rni- caceous
3l Silt, olive-gray' cornpact, larninated
3l Sand, gray to yellow, rnediurn-grained, rnicaceous, with silt larninae' con- taining pebbles
8l Sand, gray to buff' rnediurn- to coarse-grained, cross-bedded, arkosig rnicaceous, containing pebbles, and clay balls
Berry (1912) recorded the following plant species frorn this area:
Arthrophyta Equiseturn burchardti (Dunker) Brongniart
Pte ridophyta Scleropte ri s elliptica Fontaine Onychiopsis goepperti (Schenk) Berry Cladophlebis parva Fontaine
Cycadophyta Podozarnites sp. Dioonites buchianus (Ettingshausen) Bornelnann 9
Coniferophyta Feistrnantelia oblonga Ward Nageiopsis zarnoides Fontaine Nageiopsis longifolia Fontaine Sequoia arnbiqua Heer Sphenolepis kurrianurn (Dunker) Schenk Sphenolepis sternbergiana (Dunker)
Figure 4. Cross-bedded sands with clay balls and lenses which occur in the Patu.xent forrnation - note iron oxide stains
3.9 32. O Return to and turn left on U. S. Highway l.
L.Z 33.2 Turn left on State Road 633.
I.3 34.5 On left: Outcrop of cross-bedded sands of the Patuxent forrnation.
2.6 37. I STOP 2: PATAPSCO FORMATION - RAILROAD CUT NEAR POSSUM POINT (45 rninutes)
Walk about 300 yards north along the railroad tracks. The Patapsco forrnation crops out for a short distance along the railroad.
Thicknes s De sc ription
PLEISTOCENE 4l Gravel and loarn, brown, sandy
PATAPSCO FORMATION 4l Clay, buff, very plastic
z0' Clay, red-brown to pink with gray rnottling, silty, few pebbles
6l CLay, gray to buff, very plastic Coniferophyta Feistrnantelia oblonga Ward Nageiopsis zarnoides Fontaine Nageiopsis longifolia Fontaine Sequoia arnbiqua Heer Sphenolepis kurrianurn (Dunker) Schenk Sphenolepis sternbergiana (Dunker)
'4+!.fu
-;-,!* n: ,r.,.!.r
. '..:'j 1
Figure 4. Cross-bedded sands with clay balls and lenses which occur in the Patuxent forrnation - note iron oxide stains
?q 32. O Return to and turn left on U. S. Highway l. r.z 33. Z Turn left on State Road 533.
1.3 34.5 On left: Outcrop of cross-bedded sands of the Patuxent forrnation.
2.6 37. I STOP 2: PATAPSCO FORMATION - RAILROAD CUT NEAR POSSUM POINT (45 rninutes)
WaIk about 300 yards north along the railroad tracks. The Patapsco forrnation crops out for a short distance along the railroad.
Thickne s s De sc ription
PLEISTOCENE 4l Gravel and loarn, brown, sandy
PATAPSCO FORMATION 4l C1ay, buff, very plastic
z0l CIay, red-brown to pink with gray rnottling, silty, few pebbles
6l Clay, gray to buff, very plastic l0
0.3r Sandstone, red-brown, lirnonitic
3l Sand, gray-brown, rnediurn-grained
Figure 5. Variegated clay strata of the Patapsco forrnation
Berry (1912) recorded the following plant fossils frorn this area:
Pteridophyta Acrostichopteris longipennis Fontaine
Conif e rophyta Brachyphyllurn c ras sicaule Fontaine Sphenolepis sternbergiana (Dunker) Schenk
Cycadophyta Zarnites tenuinervis Fontaine
Angios perrnophyta Sassafras sp.
4.0 4t. L Return to and turn left on U. S. Highway l.
I.0 42. I On right: Outcrop of Quantico slate at base of hill.
Nurnerous outcrops of the Potornac group occur between Durnf ries and Fredericksburg.
zo.4 62.5 Turn left after crossing the Rappaharinock River, and proceed on Princess Anne Street into F r ed e ri cksburg. l0
0. 3 Sandstone, red-brown, lirnonitic
3 Sand, gray-brown, rnedirrrn- grained
:i'u' ::,
,o.t:t
.;: r.
Figure 5. Variegated clay strata of the Patapsco forrnation
Berry (19I2) recorded the following plant fossils frorn this area:
Pte ridophyta Ac rostichopte ris longipennis Fontaine
Conif e rophyta Brachyphyllurn c ras sicaule Fontaine Sphenolepis sternbergiana (Dunker) Schenk
Cycadophyta Zarnites tenuinervis Fontaine
Angios perrnophyta Sassafras sp.
4.0 41. L Return to and turn left on U. S. Highway I.
I.0 A) 1 On right: Outcrop of Quantico slate at base of hill.
Nurnerous outcrops of the Potornac group occur between Durnf ries and Fredericksburg. zo.4 62.5 Turn left after crossing the Rappaharinock River, and proceed on Princess Anne Street into F red ericksburg. ll t.3 63.8 Turn left on State Highway 3.
0.4 64. Z Cross the Rappahannock River and turn left on State Highway 218.
8.4 72.6 Turn left on State Road 600 at Cities Service gas stati on.
2.3 74.9 Turn right on State Road 654.
3.2 78. I STOP 3: AQUIA FORMATION - BELVIDERE BEACH (45 rninutes). See "Virginia Minerals, I' vol. 8, no. 3, fig. 3, 1962.
Walk about 100 yards upstream. The Aquia for- rnation crops out along the river bluff.
Figure 6. Fossiliferous layers in the Aquia forrnation
Thicknes s DescriPtion
PLEISTOCENE 3' Sand, brown, coarse-grained
AQUIA FORMATION l0l Sand, buff, fine-grained, unfossili- fe rous
2l Sand, brown, fine-grained, glauconitic, argillaceous, fos siliferous
5l Sand, gray-green, fine-grained, glauconitic, argillaceous, fossiliferous II
I.3 63.8 Turn left on State Highway 3.
0.4 64. Z Cross the Rappahannock River and turn left on State Highway 2L8.
8.4 72.6 Turn left on State Road 600 at Cities Service gas s tati on.
2.3 74.9 Turn right on State Road 654.
3.2 78. I STOP 3: AQUIA FORMATION - BELVIDERE BEACH (45 rninutes). See I'Virginia Minerals,rr vol. 8, no. 3, ftg. 3, 1962.
Walk about 100 yards upstrearn. The Aquia for- rnation crops out along the river bluff.
Figure 6. Fossiliferous layers in the Aquia forrnation
Thickne s s Description
PLEISTOCENE 3l Sand, brown, coarse-grained
AQUIA FORMATION l0l Sand, buff, fine-grained, unfossili- fe rous
z Sand, brown, fine-grained, glauconitic, argillaceous, fos siliferous
5 Sand, gray-green, fine-grained, glauconitic, argillaceous, fossiliferous lz
Berry (L934, 1936) recorded the following plant species frorn this locality:
Pinus lynni Ficus aquiana
Gildersleeve (l94Zl recorded the following fauna frorn this locality:
Pelecypoda Cucullaea gigantea Vene ricardia planicosta Pecten johnsoni Ostrea cornpres sirostra Meretrix ovata C ras satellites alaeforrni s Protocardia lenis
Gastropoda Fulguroficus argutus Tudicla rnarylandica Turritella rnortoni var. post-rnortoni Turritella rnortoni Turritella hurnerosa Vertebrata MyLiobatus rnagister Myliobatus copeanus Thecacharnpsa s e ricodon Odontaspis elegins Otodus obliquus Phyllodus rnedius Phyllodus toliapicus Phyllodus rnarginalis Phyllodus speciosus Trionyx virginiana
5.5 83. 6 Return to and turn left on State Highway 218.
5.2 88. 8 Turn left on State Road 609.
1.0 89. 8 STOP 4: AQUIA FORMATION - FAIRVIEW BEACH (l hour and l5 minutes)
OBTAIN PERMISSION to gain access to beach pG""-1i.". Ru"id.rt" have asked that SAMPLES NOT BE TAKEN frorn the boulders that are pre- sent on the beach. Walk about 25 yards up- strearn. Indurated boulders of the Aquia forrna- tion crop out at the base of the river bluff.
Thicknes s Des c ription
PLEISTOCENE 3l Gravel and loarn, buff, sandy
AQUIA FORMATION ? LZI Sand, brown to buff, fine-grained, rnicaceous l3
AQUIA FORMATION ) Sandstone, gray-brown, fine-g rained, glauconitic, calcareous, with nurnerous fossil rnolds and casts, pa rti cularly of Turritella rnortoni.
.,.;!.;4:N;i1i,$Si;1't,:: ":, : :rr..:.:!r':::::r":i*.Pr.iiir:,,::,,;', Figure 7. Blocks of calcareous sandstone frorn the Aquia forrnation containing casts and rnolds of Turritella rnortoni
Cushrnan (1944)' recorded the following Forarninifera from this locality:
Reophax curtus Cushrnan Haplophragrnoides cf. sphaeriloculurn Cushrnan Spiroplectarnrnina wilcoxensis Cushrnan and Ponton Gaudryina sp. T rocharnrnina howei Cushrnan Robulus wilcoxensis Cushrnan and Ponton Darbyella wilcoxensis Cushrnan and Garrett Globulina gibba drOrbigny Pseudopolyrnorphina wilcoxensis Cushrnan and Ponton Sigrnornorphina sernitecta (Reuss) var. terquerniana (Fornasini) Bulirnina ovata d'Orbigny Anguloge rina virginiana Cushrnan Valvulineria wi"lcoxensis Cushrnan and Ponton Eponides lotus (Schwager) Siphonina wilcoxensis Cushrnan Pulvinulinella obtusa (Burrows and Holland) Anornalina urnbonifera (Schwager)
1.0 onR Return to and turn left on State Highway Zl8 and proceed one rnile to junction of State Highway 218 and State Road 609. t3
AQUIA FORMATION 5 Sandstone, gray-brown, fine - g rained, glauconitic, calcareous, with nurnerous fossil rnolds and casts, pa rti cularly of Turritella rnortoni.
:;?.
' -r)..?
Figure 7. Blocks of calcareous sandstone frorn the Aquia f orrnation containing casts and rnolds of Turritella rnortoni
Cushrnan (1944l. recorded the following Forarninifera frorn this locality:
Reophax curtus Cushrnan Haplophragrnoides cf, sphaeriloculurn Cushrnan Spiroplectarnrnina wilcoxensis Cushrnan and Ponton Gaudryina sp. T rocharnrnina howei Cus hrnan Robulus wilcoxensis Cushrnan and Ponton Darbyella wilcoxensis Cushrnan and Garrett Globulina gibba drOrbigny Pseudopolyrnorphina wilcoxensis Cushrnan and Ponton Sigrnornorphina sernitecta (Reuss) var. terquerniana (Fornasini) Bulirnina ovata d'Orbigny Angulogerina virginiana Cushrnan Valvulineria wilcoxensis Cushrnan and Ponton Eponides lotus (Schwager) Siphonina wilcoxensis Cushrnan Pulvinulinella obtusa (Burrows and Hol).and) Anornalina urnb onif era (Schwag e r)
1.0 90. 8 Return to and turn left on State Highway Zl8 and proceed one rnile to junction of State Highway 218 and State Road 609. I4
0.0 0.0 To alternate stoP, STOP 5, bear left on State Highway 218.
7.2 7.2 Turn left on State HighwaY 206.
2.3 9.5 Turn left on State Hig}.way 624.
1.7 rt. z Bear left on State Road 624.
0.4 r1.6 Turn left on gravel road (rnarker sign, rrScogginrr).
L.Z LZ,8 ALTERNATE STOP - STOP 5: NANJEMOY FORMATION - \MOODSTOCK Walk about 20 yards to the right of the house and follow path down to the River. The Nanjernoy forrnation crops out about 20 yards downstream frorn the Dath at the base of the bluff.
Figure 8. Atgillaceous greensand of the Nanjernoy forrnation
Thicknes s De s criPtion
NANJEMOY FORMATION ro' Sand, red-brown, fine-grained, clay content increases toward the upper part; rnaterial is rnottled red and buff.
l0l Sand, olive to brown, fine-grained, glauconitic, silty, locally argillaceous, and containing thin larninae of rnediurn- g rained. sand,
Clark and Miller (1912) recorded the f ollowing invertebrate species frorn the lowest six feet of this section, which they called the Potapaco rnernbe r:
Pelecypoda Venericardia potapacoensis t4
0.0 0.0 To alternate stop, STOP 5, bear left on State Highway 2I8.
7.2 7.2 Turn left on State Highway 206.
2.3 q( Turn left on State Highway 624.
t.7 Lt. z Bear left on State F.oad 624.
o.4 ll.6 Turn left on gravel road (rnarker sign, rrScogginrr).
t.z lz.8 ALTERNATE STOP _ STOP 5: NANJEMOY FORMATION - WOODSTOCK Walk about Z0 yards to the right of the house and follow path down to the River. The Nanj ernoy forrnation crops out about 20 yards downstrearn frorn the oath at the base of the bluff.
Figure 8. Argillaceous greensand of the Nanjernoy forrnation
Thicknes s De s c ription
NANJEMOY FORMATION I6' Sand, red-brown, fine-grained, clay content increases toward the upper part; rnaterial is rnottl.ed red and buff.
l0 Sand, olive to brown, fine-grained, glauconitic, silty, locally argillaceous, and containing thin larninae of rnediurn- g rained. sand. Clark and Miller (1912) recorded the following invertebrate species frorn the lowest six feet of this section, which they called the Potapaco rnernbe r:
Pelecypoda Venericardia potapacoensis l5
Gastropoda Tornatellaea bella Conrad Cylichna venusta Clark Ringicula dalli Clark
The following invertebrate species were recorded by Clark and Miller (1912) frorn the next 2O feet of the section, which they called the Woodstock rnernber:
PelecyPoda Corbula oniscus Conrad Meretrix subimpres sa Conrad Pecten dalli Clark Ostrea sellaeforrnis Conrad Glycyrneris idoneus (Conrad) Leda cultelliforrnis (Rogers) Protocardia lenis Conrad
Gastropoda Mitra potornacensis Clark and Miller Mesalia obruta (Conrad) Strepsidura subscalarina Heilprin Turitella potornacensis Clark and Miller
Gildersleeve (19421 recorded the following species frorn this locality:
Pelecypoda Ostrea s ellaef orrnis Meretrix ovata Corbula sp. Corbula aldrichi Vene ricardia potapacoensis Nucula ovula Leda cultelliforrnis Leda parva Leda sp.
Gastropoda Turritella potornacAnsis Litiopa rnarylandica
Forarninif era Cibicides fletcheri Cibicides conoides Cibicides lobatulus Cibicides sp. Planularia sp. Bulirnina g racili s Globigerinia bulloides Globigerinia sp. Lagena sulcata Nonion pizarrensis Polyrnorphina austriaca Globulina gibba Pyrulina albatros si Rotalia bec ca rii Valvuline ria floridans Discorbis sp. I6
Ostracoda Cytheridea perarcuata Cytheridea mulleri Cythere rnarylandica Cythere oliveri Cythere sp. Bairdiidae subdeltoidea
l. t L3.9 Return Lo and turn right on State Road 624.
z.l 16. 0 Turn left on State Highway 206.
0.7 r6.7 Turn right on U. S. Highway 30 l.
8.8 25.5 Turn left on State Highway 3 at intersection of U. S. Highway 301 and State Highway 3. At this intersection, return to route between Stops 4 and 6.
1.0 91. 8 Turn right on State Road 609.
2.4 94. Z Turn left on State Road 677.
0.2 94.4 Turn left on State Highway 3.
5.2 99.6 Cross intersection of State Highway 3 and U. S. Highway 30 I; stay on State Highway 3.
19.4 119.0 Turn left on State Highway ZL4 at Atlantic service station.
L.Z tzo. z Turn left at Stratford HaIl and Plantation.
z.L r22.3 STOP 6: CALVERT, CHOPTANK, AND ST. MARYS FORMATIONS _ STRATFORD CLIFFS (l hour and 15 rninutes)
Walk upstrearn frorn the Old Mill for about 25 yards. The Calvert, Choptank, and St. Marys forrnations crop out along the river in the Strat- ford Cliffs.
Thicknes s De s c ription
PLEISTOCENE 401 Sand, red-brown to buff, coarse- grained, containing sorne gravel
ST. MARYS FORMATION 3l Clay, red-brown, very plastic, larninated, contains nodules and larninae of iron oxide.
5l Clay, dark gray, very plastic
CHOPTANK FORMATION 35' Sand, olive, fine-grained, becornes argillaceous upward L7
0. 51 Sandstone, red-brown, lirnonitic
6l Sand, brown, fine-grained, argil- lac eous
CALVERT FORMATION 35' Clay, olive to brown, cornpact, sandy, well jointed and stained with iron oxide, contains diatorns, be- comes rnore sandy upward
Figure 9. Diatomaceous clays of the Calvert forrnation
Mansfield (L9431 placed the upper iirnit of the Calvert forrnation at this locality about 5 feet above a thin bed containing Isocardia, Mansfield recorded the following invertebrate species f rorn the Choptank forrnation at this locality:
Pelecypoda Cras satellites rnarylandicus (Conrad) Crassatellites turgidulus (Conrad) Phacoides crenulatus (Conrad) Diplodonta subvexa (Conrad) Isocardia fraterna (Say) var. Cardiurn s p. Venus plena (Conrad) ? Pecten rnadisonius Say Arca starninea Say Pecten rnarylandicus Wagner Astarte obruta Conrad Thracia sp. Dosinia sp. Corbula idonea Conrad l7
0.51 Sandstone, red-brown, Iirnonitic
6l Sand, brown, fine-grained, argil- lac e ous
CALVERT FORMATION 35' Clay, olive to brown, cornpact, sandy, well j ointed and stained with i.ron oxide, contains diatorns, be- corrres rnore sandy upward
,.; l
Figure 9, Diatornaceous clays of the Calvert forrnation
Mansfield (1943) placed the upper lirnit of the Calvert forrnation at this locality about 5 feet above a thin bed containing Isocardia. Mansfield recorded the following invertebrate species f rorn the Choptank forrnation at this locality:
Pelecypoda Cras satellites rnarylandicus (Conrad) Cras satellites turgidulus (Conrad) Phacoides crenulatus (Conrad) Diplodonta subvexa (Conrad) Isocardia fraterna (Say) var. Cardiurn s p. Venus plena (Conrad)? Pecten rnadisonius Say Arca starninea Say Pecten rnarylandicus Wagner Astarte obruta Conrad Thracia sp. Dosinia sp. Corbula idonea Conrad l8
Mansfield (lg43l recorded the following invertebrate species frorn the St. Marys forrnation frorn this locality:
Pelecypoda Glycyrneris subovata (Say) var. Arca sp. Ostrea disparilis Conrad Astarte aff. obruta Conrad Euloxa latisulcata (Conrad) Chione cf. athleta Conrad Spisula confraga (Conrad) Corbula sp.
Gastropoda Turritella plebeia Say Turritella variabilis Conrad
z.l L24.4 Return to and turn right on State Highway 214.
1.3 t25.7 Turn left on State Highway 3. t8. z r43.9 Turn left on U. S. Highway 360 at Warsaw.
5.7 r49.6 Cros s Rappahannock River.
1.3 r50.9 Turn left on U. S. Highway 17 - 360 at Tappahan- nock.
2.5 L53.4 Turn left on U. S. HighwaY 17.
59.7 zL3. I Cross York River via George P. Colernan Mernorial Bridge.
0.3 2L3.4 Turn right on Colonial Parkway at Yorktown.
LT.4 224.8 Turn right on State Highway L3Z Y at Inforrnation C enter.
0.4 zz5. z Turn left on State Highway l32.
0.8 ?,26. o Turn right on Duke of Gloucester Street.
0. I 226. I Turn right at Williarn and Mary College and pro- ceed west on U. S. Highway 6O Z ot Richrnond Road.
0.8 z26. g END OI'FIRST DAYIS TRIP l9
SECOND DAY OF FIELD CONFERENCE Saturday, October 13, 1962
Departure tirne, 8:15 a. rn. E. S. T. (9:15 a. rn. E. D. T. ) Williarnsburg, Virginia
Mileage Accurnulative Mileage Itinerary
0.0 0.0 Proceed to Colonial Parkwav.
t.7 L.7 Bear right on State Highway L3Z Y.
0.4 z.I Turn left on Coloni.al Parkway.
13.3 t5.4 Cross State Highway 238 and proceed to Visitor Center of Yorktown Battlefield. Stop and OBTAIN PERMISSION frorn the Superintendent of Gf"i-i"f N"ti"""l Hi"t"rical Park to gain access to the beach area.
o.4 15. 8 Turn right on Itone wayrr dirt road.
0.3 16. r STOP 7: YORKTOWN FORMATION - COLONIAL NATIONAL HISTORICAL PARK, YORKTOWN BATTLEFIELD, NEAR BRITISH REDOUBT #10 (1 hour and l5 rninutes). See 'rVirginia Minerals, I' vol. 8, no. 3, p. 7 #6 (figures 4 and 5), t962
Follow path down to the river and walk upstream a short distance. The Yorktown forrnation crops out at several locations along the right bank of the York River.
Thicknes s Description
YORKTOWN FORMATION 6t Shell layer, brown, indurated
lzt Coquina, tan, soft, cross-bedded, slightly sandy, with thin lirnonitic lenses, and a few Iarge shells 6t Coquina, red-brown, slightly in- durated, with thin lirnonitic lenses and a few large shells
Extensive collections of both rnacro and rnicro-fossils have been rnade frorn the bluffs ex- tending along the York River in this area. Thirty significant fossils frorn the Yorktown for- rnation at Yorktown are listed (Roberts, L9321:
Coelenterata Astrangia lineata Conrad Septastrea rnarylandica Conrad zo
Pelecypoda Arca centenaria Say Arca incile Say Asaphis centenaria Conrad Astarte undulata Say Carditarne ra arata Conrad Cras satellites undulatus Say Dosinia acetabulurn Conrad Glycyrneris arnericana De France Glycyrneri s subovata Say Ostrea disparilis Conrad Pecten jeffersonius var. edgecornbensis Conrad Pecten rnadisonius Say Pli.catula rnarginata Say Teredo calamus Lea Venericardia granulata Say Venus tridacnoides Larnark
Ga stropoda Calliostorna philanthropus Conrad Crepidula aculeata var. costata Conrad Crepi.dula plana Say C rucibulurn constricturn Conrad Ecphora quadricostata Say Fissuridea redimicula Say Oliva litterata Larnark Polynices heros Say Turritella alticostata Corrad Verrnetus virginica Conrad
Scaphopoda DentaU.urn attenuaturn Sav
A rthropoda Balanus convavus Brown
;: *-'! :; ,-':
Figure l0' Fossiliferous beds and cross-bedded strata of the Yorktown forrnation z0
Pelecypoda Arca centenaria Say Arca incile Say Asaphis centenaria Conrad Astarte undulata Say Carditarne t a arz-ta C onrad C ras satellites undulatus Say Dosinia acetabulum Conrad Glycyrneris arnericana De France Glycyrneris subovata Say Ostrea disparilis Conrad Pecten jeffersonius var. edgecornbensis Conrad Pecten rnadisonius Say Plicatula rnarginata Say Teredo calarnus Lea Venericardia granulata Say Venus tridacnoides Larnark
Gastropoda Calliostorna philanthropus Conrad Crepidula aculeata var. costata Conrad Crepidula plana Say C rucibulurn constricturn C onrad Ecphora quadricostata Say Fissuridea redirnicula Say Oliva litterata Larnark Polynices heros Say Turritella alticostata Corrad Verrnetus virginica Conrad
Scaphopoda Dentaliurn attenuaturn Say
A rthropoda Balanus convavus Brown
i.a.'
i',g ar ..... !:?::,-,
Figure 10. Fossiliferous beds and cross-bedded strata ol the Yorktown forrnation zl
0.3 16.4 Proceed on rrone waytr dirt road and turn right on State Highway 238.
0.0 0.0 To alternate stop - STOP 8, turn left on State Highway 238.
0. 0.7 Turn left on State Road 676.
0. 0.8 Turn right on first dirt road into parking 1ot.
0. I 0.9 ALTERNATE STOP - STOP 8: YORKTOWN FORMATION - MOORE HOUSE Follow path down to river and walk upstrealn about 50 yards. The Yorktown forrnation crops out for several rniles frorn this point westward along the York River.
fi:;fa :::1:i:: i*}.:, ::{:.' ii:-r:i:: t! 11.:9 19,,.1 rB.- . :4!rl i;f:., ii :i!;
Figure l l Shel1 rnarl of the Y orktown forrnation
Thickne s s Description
YORKTOWN FORMATION l5' Sand, brovn'n to gray-brown, rnedi.urn- to fine-grained, slightly fossiliferous
l5' She11 rnarI , gray, sandy, slightly ar- gilla c eous
5l Sand, brown, mediurn-grained, ve ry argillaceous, fos siliferous
See fossil list of STOP 7 zl
0.3 r6. 4 Proceed on 'rone way'r dirt road and turn right on State Highway 238.
0.0 0. 0 To alternate stop - STOP 8, turn left on State Highway 238.
0. 7 Turn left on State Road 576.
0. 1 0.8 Turn right on first dirt road into parking lot.
0. I no ALTERNATE STOP _ STOP 8: YORKTOWN FORMATION _ MOORE HOUSE
Follow path down to river and walk upstrearn about 50 yards. The Yorktown forrnation crops out f or several rniles f rorn this point westward along the York River.
Figure I I Shell rnarl of the Yorktown forrnation
Thickne s s Description
YORKTOWN FORMATION l5' Sand, brown to gray-brown, rnediurn- to fine-grained, sli.ghtly f os silif erous Shell rnarl, gray, sandy, slightly ar- gilla c eous
5l Sand, brown, rnediurn-grained, very argillaceous, fos siliferous
See fos sil list of STOP 7 zz o.z I. I Return to and turn right on State Highway 238.
0.7 l. 8 Proceed on State Highway 238 to intersection of State Highway and "one way" dirt road of Y orktown Battlefi,eld.
1.4 I7. 8 Straight ahead on State Road 1001 at intersection of State Highway 238 and State Road l00l (about one block).
0. I 17. 9 Turn right on U, S, Hi.ghway 17 and cross George P. Colernan Mernorial Bridge.
)A l 42. 0 Turn left on State Highway 14 at Adner.
6.4 48. A Turn left and stay on (nearest two-lane highway) State Highway 14.
1.8 50. z Turn right and stay on State Highway 14-
52. 8 STOP 9: ST. MARYS FORMATION - CORBIN CREEK (30 rninutes). See "Virginia Minerals, " vol. 8, no. 3, P. 7 #5 (figures 4 and 5), 1962
The St. Marys forrnation crops out along Corbin Creek, on the left irnrnediately below the bridge. Access to the forrnation rnay be gained by crossing bridge and walking along path through woods.
Figure IZ. Isognornon rnaxillaturn zone in the St. Marys forrnation
Thicknes s Description
PLEISTOCENE f' Sand, buff, to brown, fine-grained, argillaceous, containing gravel in s orne plac e s zz
0.2 1l Return to and turn right on State Highway Z 38. of 0.7 I.8 Proceed on State HighwaY 238 to intersection State HighwaY and Ione waYil dirt road of Y orktown Battlefield.
1.4 17.8 Straight ahead on State Road I00I at intersection of State Highway 238 and State Road I00I (about one block). George 0. I 17.9 Turn right on U. S. Highway 17 and cross P, Colernan Mernorial Bridge.
24. I 42. 0 Turn left on State Highway I4 at Adner'
A and stay on (nearest two-lane highway) 6. a^ 48. Turn left State HighwaY 14' l4' 1.8 50. z Turn right and stay on State Highway CORBIN L.b l) 8 STOP 9: ST. MARYS FORMATION - CREEK (30 rninutes). See "Virginia Minerals, " vol. 8, no' 3' P' 7 #5 (figures 4 and 5) ' 1962
The St. Marys f orrnation crops out along Corbin Creek, on the left irnrnediately below the bridge' Access to the forrnation rnay be gained by crossing bridge and walking along path through woods'
"):jtil
Figure I Z. Isognornon rnaxillaturn zone in the St. MarYs forrnation Thicknes s Description
PLEISTOCENE 5' Sand, buff, to brown, fine-grained, argillaceous, containing gravel in s orne plac e s 23
ST. MARYS FORMATION 5I Sand, blue-gray, fine-grained, very fossiliferous, argillaceous.
The following invertebrate species frorn this locality are listed (Ruhle, L96zl:
Brachiopoda Discinisca lugubris
Pelecypoda Is ognornon rnaxillaturn Chlarnys jeffersonia Anornia aculeata
Gastropoda Callio storna philanthropwn Turritella altico stata Ecphora quadricostata
Scaphopoda Dentaliurn attenuaturn
Arthropoda Balanus concavus
1.8 54.6 Proceed to and turn right on State Road 603.
6.6 6t. z Turn left on State Road 512.
2,7 63.9 Turn left on U. S. Highway 17.
71.6 Turn ri.ght on State Road 602 at Oakley.
1.6 73. Z Turn right on State Road 644.
0.6 73.8 Straight ahead on State Road 556, proceed to South Hill Bank.
0.9 74.7 Turn left on Pine Tree Road.
0.4 75. I Turn right on River Side Drive. 0.3 75.4 STOP IO: ST. MARYS FORMATION - NEAR BOWLER'S WHARF (1 hour)
Walk about 100 yards upstrearn. The St. Marys forrnation crops out for nearly a rnile along the right bank of the Rappahannock River.
Thickne s s DeBc ription
PLEISTOCENE l5' Sand, gray to red-brown, rnediurn- grained, silty, rninor arnounts of gravel )A
ST. MARYS FORMATION TZ' Sand, greer.- gray, very fine-grained, argillaceous, slightly glauconitic, fos siliferous, particularly Spisula tftggt"tCj:g) ra Ppahanno ck en s i s Gardner
Figure t 3. Fossiliferous argillaceous sand and silt strata of the St. Marys forrnation
The followi.ng fossils were recorded frorn this area (Clark and Mil1er, I9LZI
Pelecypoda Arca starninea Say Venus Ostrea
Gastropoda Fulgur coronaturn Conrad Turritella plebeia Say
Scaphopoda Dentaliurn attenuaturn Sav
Gardner (L943, 1948) recorded the following fossils frorn this area:
Pelecypoda Nucula proxirna Say Pododesrnus (Monia?) philippi Gardner Dosinia (Dosinidia) acetabulurn Conrad Venus (Mercenaria) berryi Gardner Macorna virginiana Conrad Spisula (Mactrorneris) bowlerensis Gardner Spisula (Hernirnactra) rappahannockensis Gardner Kuphus calarnus Lea )A
ST. MARYS FORMATION TZ' Sand, green-gray, very fine-grained, argillac eous, slightly glauconitic, fossiliferous, particularly Spisula (Hernirnactra) rappahannockensi s Gardne r
Figure I 3. Fos silif erous argillaceous sand and silt strata of the St. Marys forrnation
The following fossils were recorded frorn this area (Clark and Miller, lglzll
Pelecypoda Arca starninea Say Venus Ostrea
Gastropoda Fulgur coronaturn Conrad Turritella plebeia Say
Scaphopoda Dentaliurn attenuaturn Say
Gardner (L943, I948) recorded the following fossils frorn this area:
Pelecypoda Nucula proxirna Say Pododesrnus (Monj-a ? ) philippi Gardner Dosinia (Dosinidia) acetabulurn Conrad Venus (Mercenaria) berryi. Gardner Macorna virginiana Conrad Spisula (Mactrorneris) bowlerensis Gardner Spisula (Hernirnactra) rappahannockensis Gardner Kuphus calarnus Lea z5
Gastropoda Turritella plebeia carinata Gardner
z.z , t. o Return to and turn right on State Road 602. 1.4 79. O Turn right on U. S. Highway l? at Center Cross. t08 187 Return to Fredericksburg via U. S. Highway lZ and Alexandria via U. S. Highway l. z6
STRATIGRAPHY
LOWER CRETACEOUS
Potornac GrouP
(Glark' 1897)' Patrrxent forrnation - The forrnation, narned frorn the Patuxent River, Maryland' generally overlies with rnarked constitutes the basal portion of the Potornac group. The Patuxent In a lirnited area around unconforrnity the crystalline rocks beneath the coastal Plain sedirnents. sedirnents' Doswell, about 20 rniles north of Richrnond, the Patr'rxent overlies Triassic and in horizontal The lithologic character of the Patuxent forrnation is varied in vertical rnost of directions. The deposits consist chiefly ofgtay to buff arkosic sands and sandstones are corrrrnon in the which are cross-bedded. Chloritic clays are locally abundant' Gravels throughout strata Patuxent deposits. They occur in distinct beds or are irregularly distributed areas along the Ap- of fine rnaterials. Indurated arkosic conglornerate is present in several and over a pornattox and James rivers. The sands of this forrnation locally are indurated' a sandstone frorn this forrna- hundred years ago were used as a building stone. At Aquia creek portion of the Capitol' and tion was quarried for the construction of the White House, the otd also built of this other public buildings in Washington. The old lighthouse at Cape Henry is or the sand and clay beds are Aquia ,,freestone. r' Beds of sand grade laterally in layers of clay color and therefore interstratified, The Patr:xent clays are generally uniforrn gray to buff in Patapsco forrnation' can be readily distinguished frorn the variegated clays of the is approxirnately north' The general strike of the patuxent forrnation throughout Virginia rocks upon which The dip is east at a rate of about 50 feet a rnile. The surface of crystalline deposits i's not uniforrn' the forrnation rests is irregurar so that the thickness of the overlying sands and con- where exposed, the Patuxent beds are frorn z5o to 300 feet thick' The Patr-r'xent have been collected frorn glornerates are in general unfossiliferous, but many species of flora
clay balls, and lenses, and the rrrore argillaceous sands' The position of The pat'xent waters rnay have been shallow and estuarine in character' directions of the currents larninations in cross-bedded sands and gravels is evidence that the shows the proxirnity to the were diverse. The presence of nurnerous land plants in the clays
land (Clark and Miller' l9l?l' z7
PataPsco formation - The forrnation received its narne from the Patapsco River, Maryland, (Clark, 18971. The forrnation overlies unconforrnably the Patuxent forrnation in Virgini.a. The upper surface of the Patapsco is irregular and apparently was eroded in pre-Eocene tirne. The contact between variegated clays of the Patapsco forrnation with overlying greensands of the Aquia formation is easily recognized.
The lithology of the Patapsco, like that of the Patuxent forrnation, is different f rorn place to place' Patapsco sedirnents are lnore uniform and finer-grained than those of the patuxent and consist chiefly of variegated clays that grade into lighter colored sandy clays. In virginia the sedirnents are generally lighter in color than those of Maryland and contain srnaller amounts of iron oxides' The strike of the Patapsco beds in Virginia is approxirnately north and the dip is east at a rate of about 30 feet a rnile. The thickness of the forrnation where it is exposed is about 150 feet. The Patapsco deposits contain a few molluscan fossils that lived in a brackish habitat; these fossils are indicative of local estuarine conditions (Clark and Miller, L9lzl .
UPPER CRETACEOUS - PALEOCENE
Mattaponi forrnation - Upper Cretaceous - Paleocene sedirnents are distinguished primarily by the contained Forarninifera and have been narned the Mattaponi forrnation (Cederstrorn, lgs1l . These sedirnents are recorded frorn rrany wells north of the Jarnes River. The type section oc- curs in wells that are in westrnoreland County at Washingtons Birthplace and Colonial Beach. The abundance of fossils in the Mattaponi forrnation is varied. Lithologically, the unit ranges frorn variegated clays, comrnonly rnottled, to dark clays and glauconitic sands.
PALEOCENE AND.EOCENE
Parnunkey group
Aquia forrnation - The Aquia forrnation received its narne from Aquia creek, stafford county, virginia (clark and others' l90l). It overlies unconforrnabry the irregularly eroded surface of the forrnations of the Potornac group. The forrnation consists prirnarily of rnediurn- to fine- grained glauconitic sands, or greensands, that are locally cernented with silica. Sorne green- sands are interbedded with shell layers; comrnonly these occur in outcrops as ledges and nodules that range up to 4 feet thick. The greensands have rninor arnounts of rnuscovite and rnay weather z8
beds are to a reddish brown or yellow color because of the iron oxide content' Argillaceous Coarse sands present; there is less clay in the Aquia than in the overlying Nanjernoy forrnation' and gravels occur near the base of the forrnation' at the rate of The strike of the Aquia forrnation is approxirnately north and the dip is east 100 feet where it is exposed' LZ to 15 feet a rnile, The thickness of the Aquia forrnation is about rnernber' and the The Aquia forrnation is divided into two units: the lower, or Piscataway
f rorn Piscataway upper, or Paspotansa rnernber. The Piscataway lnelnber received its name its narne frorn Creek, Prince Georges County, Maryland' The Paspotansa rnernber received of the Aquia Paspotansa Creek, King George County, Virginia. During the tirne the sedirnents and rather uniforrn forrnation were deposited, the clirnate was slightly warmer than at present (Gildersleeve' l94Zl; rn and equitable, more like that of eastern South Carolina and Florida (Shifflett' 1948)' On contrast, however, the Forarninifera present are indicative of cool water been deep (Cushrnan' 1944)' the basis of the forarniniferal content, the water is believed to have deep (Shifflett' 1948)' Another writer rnade the notation that the water was at least 50 fathorns elongated basin of local The Aquia forrnation, according to Shifflett, was deposited in a narrow
extent in eastern Virginia and Prince Georges and Charles counties' Maryland'
Creek' Charles County' Nanjernoy forrnation - This forrnation received its narne frorn Nanjernoy Maryland(Clarkandothers,lg0l).Itiscornposedchieflyoffine-glainedglauconiticsandsor forrnation' and is greensands, is Iess glauconitic and less calcareous than the underlying Aquia occur in cavities devoid of indurated beds. Gypsurn (selenite) crystals, or rosettes' cornrnonly forrnation' par- that have developed at the intersection of joint planes throughout the Nanjernoy rnarked by a ZO- ticularly in the argillaceous portions. The base of the Nanjernoy is generally (frorn Marlboro' Mary- foot thick bed of cornpact white and pink clay called the Marlboro clay
land). rnernber' and the The forrnation has been divided into two rnernbers: the lower, Potapaco The Potapaco merrl- uPPer' Woodstock rnernber; each has a thickness of approxirnately 60 feet. creek' charles County' ber was narned frorn Potapaco creek that is now listed as Port Tobacco which in sorne places is Maryland on rnore recent rnaPs. It is cornposed chiefly of greensand' portion (Marlboro argillaceous and in others, gyPSeous. This rnernber, especially in its lower 7q
clay), is more argillaceous than the underlying Aquia forrnation. The lA/oodstock rnernber was
narned frorn the old hornestead, Woodstock, that was west of Mathias Point, King George County, Virginia. This rnernber is characterized by fine hornogeneous greensands that are less argilla-
ceous than the underlying Potapaco beds.
The strike of the Nanjernoy is approxirnately north and the dip is east at the rate of. lZ to
l5 feet a rnile. The thickness in outcrop is about 125 f.eet. The clirnate, as indicated bv the
characteristics of fauna in the Nanjernoy forrnation, was slightly warrner than at present.and
rather uniforrn and equitable, rnore like that of eastern South Carolina and I'lorida (Gildersleeve, L94zl.
UPPER EOCENE ( subsurface)
Chickahorniny forrnation - The Chickahorniny forrnation has been designated as Upper Eocene in age (Cushrnan and Cederstrorn, 19451 . These sedirnents are recorded from wells in the eastern part of the York-Jarnes peninsula and the type section is described frorn wells at the Navy Mine
Depot, Yorktown, York County. Lithologically, the unit consists of glauconitic and pyritic blue- gray and dull brown clays.
MIOCENE
Chesapeake group
Calvert forrnation - This forrnation received its narrre frorn calvert cliffs, calvert county,
Maryland (Shattuck, I902). It overlies unconforrnably the Nanjernoy and older sedirnentary for- rnations and in sorne places it overlaps the igneous and rnetarnorphic rocks that underlie these forrnations.
The Calvert forrnation consists prirnarity of cornpact sandy, diatornaceous clay that is dark-gray or olive and buff, where weathered. The clays locally grade into fine-grained, buJf sands, or into diatornaceous earth. Diatornaceous earth is the most distinguishing constituent of the forrnation. This rnaterial cornrnonly occurs in bold, alrnost vertical cliffs that are about
100 feet high in sorne places. Joints occur in the Calvert forrnation and are stained with iron oxide. 30
feet The strike of the Calvert forrnation is north and the dip is east at the rate of about l0 a rnile. The thickness of the beds is approxirnately 200 feet. plants that occur in the Calvert forrnation are representative of a coastal flora that had today in an affinity for warrn-ternperate waters and an environrnent sirnilar to that existing (in l9l7) noted South Carolina, Georgia, and the Gulf Coast region (Berry, 19i?)' Mann Berry' relatively warrn that the diatorns indicate a corrlparatively shallow, strictly marine habitat with proxi- or subtropical ternperature. The habitat of the Calvert pelecypods, which was in close at rnity to an estuary, probably was one of calrn, slightly saline waters and rnuddy bottorns
depths ranging frorn 2O to 25 f.athorns (Mongin, 1959)'
River' Talbot Choptank forrnation - The Choptank formation was narned frorn the Choptank Westrnore- County, Maryland (Shattuck, I90Z). It is exposed in a srnall area of Richrnond and land counties, Virginia. sand interbedded with The forrnation consists of dark-brown, unconsolidated, fossiliferous its thickness indurated sand layers. Its attitude has not been definitely deterrnined in Virgini'a; rnolluscan fauna' is approxirnately 50 feet. Because of the lirnited extent and poorly preserved in the Choptank very little is known about the Choptank forrnation in Virginia. Pelecypod fossils great depths by forrnation are believed to have accurnulated when they were transported frorn
strong currents of a transgressive sea (Mongin' 1959)'
Mary- st. Marys formation - This forrnation was narned f rorn exposures in st. Marys county'
land (Shattuck, l90Z). greensand' The The formation is cornposed chiefly of sand and clay, with beds that contain oxides' sorne beds sand is comrnonly gray and is yellow to brown where it is stained with iron occur within the forrna- of sand have been consolidated into sandstone layers. Isolated pebbles Local- tion. The clay of the St. Marys forrnation is blue to gray and is chiefly unconsolidated'
1y the sands and clays are very fossiliferous' rate of about The strike of the formation is northeast-southwest and the dip is east at the
l0 feet a rnile. The rnaximurn thickness of the forrnation is about 180 feet' unfos- Mansfield (1g43) divided the st. Marys forrnation in virginia into a lower, nearly siliferous unit that consists of dark-gray sandy clay, and an overlying fossiliferous unit that 3l
contains two faunal zones: tJre lower or zone l, the Bulliopsis quadrata zone, and the upper or zone Z, the Crassatellites rneridionalis zone. Zone I has predorninantly blue to greenish sandy
clay. Zone 2 consists of bluish sandy clay overlain by loose light-colored sands. The St. Marys
forrnation, in rnany places, was deposited in a transgressive sea and contains a genera typical of tropical or ternperate water (Mongin, lgil9l.
Yorktown formation - The yorktown forrnation was narned frorn exposures near yorktown, Vir-
ginia (Clark and Miller, 1906).
The lithology of the forrnation consists of coquina, sand, clay, sandy clay, and shell rnarl. Coquina beds range up to 50 feet thick and cross-bedded structure is well developed in sorne places. They are cornposed of pulverized rnarine rnolluscan shells, cernented bv calciurn car- bonate and are tan to reddish-brown depending upon the iron oxide content. Locally, the co- quina is a soft rnaterial, but in places is a consolidated resistant rock that has been used as a building stone. The sands are buff colored, unconsolidated, and comrnonly fossiliferous. A few grains of glauconite are distributed through the beds of sand. The clays grade into sandy clays. Most of the clay is dark-blue to gray and is very fossiliferous.
The Yorktown forrnation is one of the rnost fossiliferous forrnations represented in Atlantic Coastal Plain sediments. The fauna is rnainly rnolluscan, but other invertebrates and sorne vertebrates are present.
Mansfield (1943) divided the Yorktown forrnation in Virginia and North Carolina into two faunal zones: the lower or zone 1, Pecten clintonius zone, and the upper or zone Z, Turritella alticostata zone. Zone L consists largely of rnediurn-grained gray to buff sands. Zone Z has three parts. The lowest part contains coarse sand w"ith rrrany specirnens of Charna, gray to buff sands, and larninated clay. The rniddle part has sands and cross-bedded clays with broken shells. The upper part consists largely of gray to blue sands that weather to buff.
The strike of the forrnation is northeast-southwest and the dip is toward the southeast at the rate of a few feet a rnile. Locally, the beds are horizontal or have a slight dip to the west.
The thickness of the forrnation is approxirnately I25 feet. Rernnants of the dissected yorktown overlie the crystalline rocks in the area south of Petersburg. North of Virginia the formation is not present and has no exposed equivalent. 3Z
and At the end of the Miocene (Yorktown) a rnultitude of species of all sizes farnilies flourished abounded as in the present-day tropical seas; forrns like the Charnas and Crepidulas seas were oPen for a tirne and then slowly diminished in nurnber (Mongin, 1959)' The Yorktown assernblages' as indicated by the ostracoda (Malkin, I953) and Forarninifera (Mclean, 1956) of the Yorktown The saline seas ranged in depth Lrorn25 to 100 rneters. Fossil assernblages biostrati- forrnation rnore probably represent conternPoraneous ecological habitats rather than graphic zones (Mclean, 1956; 19571 .
PLIO-PLEISTOCENE
pleistocene and probable Pliocene sedirnents consist of a cornplex series of largely un- origin' These consolidated gravels, sands, and loarns, partly of fluvial and partly of rnarine de- sedirnents, which range up to about 50 feet in thickness, ovellie the older strata as terrace
posits. They are intirnately related to the present surface and cover the entire area, except pub- for steep bluffs where active erosion has exposed the underlying forrnations' Nurnerous -W'entworth' lications have appeared concerning these deposits, narnely those of McGee, Darton'
Cooke, and others. 33
LIST OF FOSSILS
PATUXENT FORMATION
Over.50 plant species are recorded which are diagnostic of the Patuxent forrnation. Below are listed the rnore cornmon species which are restricted to this forrnation (Berry, IglZ; Dorf, 1952):
Arthrophyta Equisetum lyelli Mantell Pteridophyta Schizaeopsis arnericana Berry Ruffordia goepperti (Dunker) Seward Acro stichopte ris parvifolia Fontaine Dryopteris dentata (Fontaine) Berry Onycheopsis brevifolia (Fontaine) Berry Taeniopteris nervosa Berry Scleropteris elliptica Fontaine
Cycadophyta Dioonites buchianus (Ettingshausen) Bornemann Zarnite s cra s sivervi s Fontaine Cycadeosperrnufit spatulaturn Fontaine Podozarnites inaequilateralis (Fontaine) Berry Coniferophyta Cephalotaxopsi s rnagnifolia Fontaine Cephalotaxopsis brevifolia Fontaine
Angio spe rrnophyta Ficophyllurn oblongifolium (Fontaine) Berry Proteaephyllum ovaturn Fontaine Rogersia longifolia Fontaine
PA TAPS CO FORMA TION
About 50 plant species are recorded whi.ch are diagnostic of the Patapsco forrnation. Below are listed the rnore comrnon species which are restricted to this forrnation (Berry, lgIZ; Dorf, 1952):
Pte ridophyta Acrostichopteris longipenni.s Fontaine
Cycadophyta Dichotozarnite s cycadop si s
Coniferophyta Araucarites aquiensis Fontaine Pinus vernonensis Ward W'iddringtonites rarnosus (Fontaine) Berry Angiospermophyta Populus potornacensis Ward Populophyllurn reniforrne Fontaine 34
Angio spe rrnoPhYta (continued) Nelurnbites virginiensis (Fontaine) Berry Nelurnbites tenuinervis (Fontaine) Berry Sapindopsis rnagnifolia Fontaine SapindoPsis brevifolia Fontaine Celastrophyllurn parvifolium (Fontaine) Berry Cela strophyllurn acutidens Fontaine Sas safras Potornacensis Berry Araliaephyllurn crassinerve (Fontaine) Berry Araliaephyllum rna gnifoliurn Fontaine Aristolochiaephyllurn crassinerve Fontaine Sterculia elegans Fontaine Ulrnophyllurn brookense (Fontaine) Knowlton
AQUIA FORMATION
The following species are found only in the Piscataway Inernber of the Aqula forrnation (Clark and Miller, 19l?):
Pelecypoda PhenacornYa Petrosa (Conrad) PholadornYa rnarYlandica Conrad Lithophaga rnarylandica Clark and Martin Ostrea cornpressirostra var' elepidota Dall
Vertebrata TrionYx virgiana Clark Synechodus clarkii Eastrnan OdontasPis elegans (Agassiz) of the The following species of invertebrates are found only in the Paspotansa mernber Aguia forrnation (Clark and Miller , Igl?li
Coelente rata Paracyathus rnarylandicus Vaughan Balanophyllia desrnophyllurn Milne Edwards and Hairne
Brachiopoda Platidia rnarvlandica Clark and Martin
Pelecypoda Diplodonta rnarlboroensis Clark and Martin Cras satellite s alta (Conrad)
Gastropoda Pleurotorna harrisi Clark Pleurotorna potornacensis Clark and Martin Cancellaria potomacensis Clark and Martin Mitra pornonkeyensis Clark and Maltin Tudicla rnarylandica Clark and Martin Calyptraphorus jacksoni Clark Aporrhais potomacensis Clark and Martin 35 Arnong the species of invertebrates which are restricted to the Aquia formation but found in both its rnernbers are (Clark and Miller, I)IZI:'
Coelenterata T rochocyathus clarkeanus Vaughan Eupsarnrnia elaborata (Conrad)
Pelecypoda Panopea elongata Conrad Meretrix ovata var. pyga (Conrad) Dosinopsis lenticularis (Roger s) Lucina aquiana Clark Venericardia planicosta var. regia Conrad Cras satellite s alaeforrnis Conrad Crassatellites aquiana Clark Ostrea cornpre s sirostra Say Leda cliftonensis Clark and Martin
Gastropoda Turritella rnortoni Conrad Turritella humerosa Conrad Scala virginiana Clark Gibbula glandula (Conrad)
The following species of Forarninifera are recorded by Gildersleeve (1942) frorn the Aquia formation:
Anornalina bilate rali s Dentalina baggi Nodosaria consorbrina Polyrnorphina gibba Robulus arnericanus Nonion pizarrensis Rotalia advena Discorbis isabelleana Epistornina elegans
Gildersleeve (19421 recorded the following Ostracoda frorn the Aquia forrnation:
Cytherella subrnarginata Cytheridea rnu l1eri Cythere plebeia Bairdia subdeltoidea
Listed below are the rnore colnlrron species of Forarninifera which are recorded frorn the Aquia forrnation of Virginia (Cushrnan, 19441:
Reophax curtus Cushrnan Spiroplectamrnina wilcoxensis Cushrnan and Ponton Robulus wilcoxensis Cushrnan and Ponton Darbyella wilcoxensis Cushrnan and Garrett Dentalina cf. cornrnunis drOrbigny Dentalina virginiana Cushrnan Guttulina cf. problerna drOrbigny Globulina gibba drOrbigny Pseudopolymorphina wilcoxensis Cushrnan and Ponton Sigrnornorphina sernitecta (Reuss) var. terquerniana (Fornasini) Bulirnina ovata Angulogerina virginiana Cushrnan Larnarckina wilcoxensis Cushrnan 36 Forarninife ra (continued) Valvulineria wilcoxensis Cushrnan and Ponton Valvulineria sc robiculata (Schwager) Pulvinulinella obtusa (Burrows and Holland) Anornalina urnbonife ra (Schwager) Cibicides Praecursorius (Schr"ags11 Cibicides howelli Toulrnin
The following species of Forarninifera are restricted to the Piscataway rr,rernber at several outcrops (Shifflett, 1948):
Quinqueloculina cf. harrisi Howe and Roberts Marginulina toulrnini Cushrnan Dentalina cf. hexacostata Howe Dentalina virginiana Cushrnan Dentalina wilcoxensi s Cushrnan Vaginulina plurnoides Plurnrner Lagena hexagona (Williarnson) Lagena laevis (Montague) Glandulina abbreviata (Neugeboren) Glandulina laevigata dr Orbigny Pseudopolyrnorphina wilcoxensis Cushrnan and Ponton Sigrnornorphina sernitecta (Reus s) Polyrnorphina advena Cushrnan, var. nuda Howe and Wallace Nonionella insecta (Schwager) Gurnbelina wilcoxensis Cushrnan and Ponton Eouvigerina excavata Cushrnan Entosolenia cf. laevigata (Reuss) Entosolenia cf. rnarginata {Walker and Jacob) Entosolenia o slatus Shifflett Virgulina wilcoxensis Cushrnan and Ponton Angulogerina parvula (Cushrnan and Thornas) Angulogerina virginiana Cushrnan Discorbis arnicus Shifflett ' Valvulineria wilcoxensis Cushrnan and Ponton Valvulineria sc robiculata (Schwager) ' Eponides labiornargus Shi{flett Pulvinulinella danvillensis Howe and Wallace Globigerina coffrpre ssa Plurnrner Globorotalia cf. angulata (White) Cibicide s rnarylandicus Shifflett Cibicides neelyi
The following species of Forarninifera are restricted in the outcroP rnaterial to the Paspotansa rnernber (Shifflett, 1948):
Arnrnodiscus incertus drOrbigny Trocharnrnina exigua Cushrnan and Applin T rochamrnina howei Cushrnan Robulus knighti Toulrnin Stichocibicide s ce rviculus Shifflett
Below are listed the rnore cornrnon species of Ostracoda which are recorded frorn the Aquia formation (Schrnidt, 1948):
Cytheropteron cf. rnidwayensis Alexander Haplocytheridea veatchi aquia Schrnidt Haplocytheridea leei (Howe and Garrett) B rachycythe re rnarylandica (Ulrich) Bythocypris parilis Ulrich 37
Ostracoda (continued) Paracythe rei s potornaca Schrnidt Clithrocytheridea virginica Schrnidt Clithrocytherid.ea malkinae Schrnidt Cythereis bassleri reticulolira Schrnidt Cythereis plusculrneni.s Schrnidt Cythereis siegristae Schrnidt Xe stoleberis longis sirna Schrnidt
The following species of planktonic Forarninifera are recorded frorn the Aquia forrnation, and are considered to be diagnostic upper Paleocene species (Loeblich and Tappan, lj57l:
Globoratalia pseudoscitula Glae s sner Globoratalia angulata (White) Globoratalia acuta Toulrnin Globigerina spiralis Bolli Globigerina triloculinoide s Plurnrner Globigerina rnckannai White
NANJEMOY FORMATION
The following species of invertebrates are found only in the Potapaco rnernber of the Nanjernoy forrnation (Clark and Miller, lgIZlz
Bryozoa Ceriopora rnicropora Goldfuss
Pelecypoda Solen lisbonensis Aldrich Luci.na astartiforrni s Aldri.ch
Gastropoda Cypraea srnithi Aldrich
The following species of invertebrates are found only in the Woodstock rnernber of the Nanjernoy fori:nation (Clark and Miller, lgl1lz
Pelecypoda Meretrix lenis (Conrad) Venericardia rnarylandica Clark and Martin Modiolus rnarylandicus Clark and Martin Leda parva (Rogers)
Gastropoda Levifusus trabeatus Conrad Pyrula penita Conrad Turritella potornacensis Clark and Martin
Scaphopoda D entaliurn rninuti striaturn Gabb Vertebrata Galeocerdo latidens Agassiz
Arnong the forrns which are lirnited to the Nanjernoy forrnation, but found in each of the rnernbers are (Clark and Miller, lglZ):
Pelecypoda Meretrix ovata var. ovata (Rogers) 38
Pelecypoda ( continued) Lucina dartoni Clark Lucina whitei Clark Venericardia potapacoensis Clark and Martin Ostrea sellaeforrnis Conrad Leda irnProcera (Conrad) Leda potomacensis Clark and Martin Leda tysoni Clark and Martin Nucula potornacensis Clark and Martin
The following species of Forarninifera are recorded by Gildersleeve (1942) frorn the Nanjemoy forrnation: Cibicides fletcheri Cibicides conoides Cibicides lobatulus Bulirnina gracilis Globigerina bulloides Lagena sulcata Nonion pizarrensis Polyrnorphina austriaca Globulina gibba Pyrulina albatrossi Rotalia beccarii Valvulineria floridans
Gildersleeve (I94Zl recorded. the following Ostracoda frorn the Nanjernoy forrnation:
Cytheridea Perarcuata Cytheridea rnulleri Cythere rnarylandica CYthere oliveri Bairdiidae subdeltoidea
CALVERT FORMATION
Below are Iisted the species of invertebrates which are lirnited to the Calvert formation (Clark and Miller, L9I2\:
Pelecypoda Arca scalaris Conrad Arca clisea DaIl Pecten virgianus Conrad Pecten rnarylandicus Wagner Anornia suffini Conrad Macorna virginiana Conrad Cooperella carpenteri Dall Solecardia cos srnani Dall Sportella constricta Conrad Sportella protexta Conrad Sportella petroPolitana Dall Sportella pelex Dall Montacuta petroPolitana Da11 Diplodonta leana Dall Diplodonta Punctulata Lea
Gastropoda Drillia lunatia Lea Adeorbis obliquistriabus Lea Adeorbis concavus Lea 39
Ga stropoda (continued) Calyptraea centralia Conrad Calliostorna humilis Conrad Teinostorna nana Lea Fis suridea catelliforrnis Rogers
The following plant species are recorded frorn the Calvert forrnation (Berry, 1917):
Pte ridophyta Salvinia forrnosa Heer
Coniferophyta Taxodiurn dubiurn (Sternberg) Heer
Angio spe rrnophyta Salix raeana Heer Quercus calvertensis Berry Carpinus grandis Unger Ulrnus basicordata Hollick Planera ungeri Ettingshausen Ficus richrnondensis Berry Platanus aceroides Goeppert Podogoniurn verginianum Berry Dalbergia calvertensis Berry Legurnino site s. calvertensis Berry Rhus rnilleri Hollick Celastrus bruckrnanni Alex. Braun Nyssa gracilis Berry Fraxinus richrnondensis Berrv
Listed beLow are the rnore cornlnon species of diatorns which are recorded frorn the Calvert forrnation (Darton, I9l l):
Coscinodi scus punctatus Coscinodiscus gigas Cos cinodiscus oculis -iridi s Systephania corona Gra spedodi scus co scinodi scus Rhizo solenia arnericana Goniothecum odontidurn Goniothecurn rogersii Biddulphia tourneyii Triceratiurn obtusurn T ric e ratiurn rna rylandicurn Pleurosigrna cf. angulaturn Spongolithus ac cicularis Spongolithus caput s e rpenti s
CHOPTANK FORMATION
Mansfield (1943) recorded the following characteristic Choptank invertebrate species, in addition to others of longer range:
Pelecypoda Isocardia fraterna glenni Gardner Arca starninea Say Pecten rnarylandicus Wagner Astarte obrupta Conrad 40 ST. MARYS FORMATION
The following species of invertebrates were found by Clark and Miller (1912) to be restricted to the St. Marys forrndion:
Pelecypoda Corbula cuneata SaY Venus rnercenaria Linne
Gastropoda Fasciolaria rhomboidea Rogers
Cushrnan and Cahill (1933) recorded the following species of Forarninifera that are restricted to the St. Marys forrnation: Massilina rnarylandica Cushrnan and Cahill Dentalina consorbrina drOrbigny var. erraciata Reuss
Below are Iisted the invertebrate fossils which were found by Mansfield (I943) to be restricted to the St. Marys forrnation:
Pelecypoda Arca idonea Conrad Glycyrneris turnulus (Conrad) Pododesrnus (Monia? ) philippi Gardner Pandora (Kennerlia) dalli Gardner Astarte (Ashtarotha) rappahannockensis Gardner Chione (Charnelea) dalli OIsson Astarte perplana Ols son Venus (Mercenaria) berryi Gardner Spisula (Mactrorneris) bowlerensis Gardner Spisula (Hernirnactra) rappahannockensis Gardner
Gastropoda Terebra (Hastula) sirnplex Conrad Oliva eboreus Conrad Fusinus parilis Conrad Alectrion peralta Conrad Turritella plebeia carinata Gardner Calliostorna hurnile Conrad
YORKTOWN FORMATION Listed below are the rnore cornlrron species of invertebrates which were found by Clark and Miller (1912) to be restricted to the Yorktown forrnation:
Pelecypoda Nucula taphria DalI Arca lirnula Conrad Spisula delurnbis Conrad Cardiurn virginianurn Conrad Gafrariurn rneta striaturn Conrad Pandora crassidens Conrad Anornia sirnPlex dtOrbignY
GastroPoda Scaphella obtusa Ernrnons Seila adarnsi Lea Drillia lirnatula Conrad 41 Gastropoda (continued) Marginella lirnatula Conrad Fulgur pyrum var. incile Conrad Fulgur rnaximurn Conrad Urosalpinx trossulus Conrad Crucibulurn auricula var. irnbricaturn Sorwerbv Crepidula {ornicata Say Fissuridea redirnicula Sav
Cushrnan and Cahill (1933) recorded the following species of Forarninifera that are restricted to the Yorktown forrnation:
Quinqueloculina larnarckiana drOrbigny Dentalina comrnunis dr Orbigny Lagena cf. rnarginato-perforata (Seguenza) Virgulina punctata drOrbigny Valvuline ria floridana Cushrnan Arnphistegina le s soni dr Orbigny
Below are listed sorne of the rnore cornryron species which were found by Mansfield (1943) to be restricted to the Yorktown forrnation:
Pelecypoda Pecten (Lyropecten) jeffersonius septenarius Say Pecten (Placopecten) clintonius Say Pecten (Placopecten) virginianus Conrad Pecten (Chalrnys) decernnarius Conrad Astarte syrnrnetrica Conrad Astarte exaltata Conrad Astarte roanokensis Gardner Astarte stephensoni Gardner Astarte atata Conrad Astarte hertfordensis rneherrinensis Gardner Astarte berryi Gardner Astarte (Ashtarotha) undulata deltoidea Gardner Astarte (Ashtarotha) undulata vaginulata Dall Astarte (Ashtarotha) concentrica bella Conrad Erycinella ovalis Conrad Cardiurn (Cerastroderrna) virginianurn Conrad Cardiurn taeniopleura Dall Isocardia fraterna carolina Dal.l Cooperella carpenteri Da1l . Venus (Mercenaria) carnpechiensis tridacnoides (Larrnarck) Gernma rnagha rnajorina Gardner Gernrna magna virginiana Dall Macorna virginiana conradi Dall Abra subreflexa Say
Gastropoda Fusinus propeparilis Mansfield Turritella oilsbrvi Gardner
The following species of Ostracoda were found by Malkin (1953) not to extend below the Yorktown forrnation:
Anornocytheridea floridana (Howe and Hough) Carnpylocythere laeva Edwards Clithrocytheridea virginiensis Malkin Cytherideis agricola flowe and Hadley Cytherideis rugipustulosa Edwards 4Z
Ostracoda (continued) Cytherideis subaequalis ulrichi Howe and Johnson Cytherideis echolsae Malkin Cytherura elongata Edwards Cytherura forulata Edwards Cythe rura wardensis Edwards Eocytheropteron yorktownensis Malkin Hernicythere conradi Howe and McGuirt Hernicythere schrnidtae Malkin Loxoconcha subrhornboidea Edwards Favella rugipunctata (Ulrich and Bassler) Paracytheridea rnucra Paracytheridea vandenboldi Puri Paracytheridea shattucki curta Malkin Paracytheridea sirnilis Malkin Trachyleberis exanthernata gornillionensis (Howe and Ellis) Trachyleberis vaughani (Ulrich and Bassler)
Malkin (1953) found that the fotlowing species of Forarninifera do not occur below the Yorktown forrnation: Discorbis consobrina Discorbis cf. assulata Eponides aff. rnansfieldi Nonion granosurn Nonion atf. pizzarense Planulina depressa Textularia articulata Textularia rnayori
Mclean (1955) listed the following species of Forarninifera the range of which is apparently restricted to the Yorktown forrnation: Textularoides carteri McLean Quinqueloculina triloculinifo rrna Mc Lean Massilina quadrans carteri Mclean Lagena palrnerae Mclean Lagena pseudosulcata Mc Lean Guttulina pseudocostatula McLean Bulirnina preacanthia McLean Bolivina lafayettei McLean Discorbis turrita Cushrnan Rotalia lirnbatobeccarii McLean Cibicides subloba (Cushrnan) Rectocibicidella robe rtsi McLean Buccella parkerae Anderson
Mclean (195?) listed the following species of Ostracoda which are restricted to the Yorktown forrnation:
Paracypris choctawhatcheensi s Puri Cytherornorpha cf. warneri Howe and Spurgeon Loxoconcha purisubrhornboidea Edwards Cytheropteron talquinensis Puri Cytherura reticulata Edwards Clithrocytheridea virginiensis Malkin Paracytheridea vandenboldi Puri Cushrnanidea echolsae (Malkin) Pterygocythereis arnericana (Ulrich and Bassler) Actinocythereis exanthernata (Ulrich and Bassler) 43 Ostracoda (continued) Actinocythereis exanthernata gornillionensis (Howe and Ellis) Murrayina barclayi McLean Acuti.cythe reis laevis sirna Edwards Cytheretta burnsi (Ulrich and Bassler) Aurilia conradi (Howe and McGuirt) 44
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