COMMONWEALTH OF VIRGINIA DEPARTMENT OF CONSERVATION AND ECONOMIC DEVELOPMENT DIVISION OF MINERAL RESOURCES GEOLOGIC STUDIES, COASTAL PLAIN OF VIRGINIA BULLETTN 83 (panrs r lNo z) VIRGINIA DIVISION OF MINERAL RESOURCES Jomes L. Colver Cornmissioner of Minerql Resources qnd Stote Geologist CHARLOTTESVILLE, VIRGINIA 1973 COMMONWEALTH OF VIRGINIA DEPARTMENT OF CONSERVATION AND ECONOMIC DEVELOPMENT DIVISION OF MINERAL RESOURCES GEOLOGIC STUDIES, COASTAL PLAIN OF VIRGINIA BUTLETTN 83 (PARTS I AND 2) VIRGINIA DIVISION OF MINERAT RESOURCES Jomes L. Colver Commissioner of Minerol Resources qnd Stqte Geologist CHARLOTTESVILLE, VIRGINIA 1973 CorruoNwnELTH oF VrncrNtA DopanrurNr oF PURoHASES AND Suppl,y RrcnmoNo t97S Portions of this publication may be quoted if credit is given to the Virginia Division of Mineral Resources. It is recommended that reference to parts 7 and 2 of this report be made in the following form: Teifke, R. H., 19?3, Stratigraphic units of the Lower Cre- taceous through Miocene series, 'ia Geologic studies, Coastal Plain of Virginia: Virginia Division of Min- eral Resources Bulletin 83, pt. 1, p. 1-78. Teifke, R. H., 1973, Paleogeology of Early Cretaceous through Miocene time, i.n Geologic studies, Coastal Plain of Virginia: Virginia Division of Mineral Re- sources Bulletin 83, pt. 2, p. 79-98. DEPARTMENT OF CONSERVATION AND ECONOMIC DEVELOPMENT Richmond, Virginia Mlnvru M. SurnnnLAND, Di,rector A. S. R.q,cHAL, JR., Euecuti,ae Assistant BOARD Wu,lram H. KING, Burkeville, Chuirman Wu,r,rltvr H. Sr.rusacnN, Falls Church, Vi,ce Chairman D. HnNny ALMoND, Richmond Ma.ron T. BnNroN, Suffolk Josrpn C. Clnrnn, Jn., Richmond A. R. DuNNrNc, Millwood ADoLF U. HoNxar,.t, Richmond Roepnr PATTERSoN, Charlottesville Fnnopnrc S. Rnnn, Manakin-Sabot Colr,INs SNyoEn, Accomac Fnnonnrcr W. Walrrn, Richmond Snnnuau War,r,.qcn, Cleveland CONTENTS 1 Part 1. Stratigraphic units of the Lower Cretaceous through Miocene series, by Robert H. Teifke Pafi 2, Paleogeology of Early Cretaceous through Mio- cene time, by Robert H. Teifke 79 Index: Parts 1 and 2 ............. 99 Part 3. Pleistocene-Holocene environmental geology, by Emil Onuschak, Jr. 103 Index: Part 3 150 1 The contents and illustrations of each part is given with each paper. PAST 1 STRATIGRAPHIC UNITS OF THE LOWER CRETACEOUS THROUGH MIOCENE SERIES By Rosnnr H. Tnmrn CONTENTS Plcr Abstract .. o Introduction 5 Methods of investigation 7 Descriptive stratigraphy 8 "Basement" rocks 8 Cretaceous System I Patuxent Formation 9 "Transitional beds" L4 Cretaceous(?) and Tertiary systems 16 Mattaponi Formation 16 Tertiary System 20 Nanjenroy Formation 20 Calvert Formation . 24 Yorktown Formation 27 Tertiary and Quarternary systems 31 Columbia Group 31 Three-dimensional distribution of sediments 31 References .. 35 Appendix I: Geologic summaries .... 36 Appendix II: Selected geologic logs 56 ILLUSTRATIONS Pr,nrn PAGE 1. Control wells and lines of well correlations ............ In pocket 2. Structure-contour map of the Patuxent Formation In pocket 3. Structure-contour map of the "transitional beds" In pocket 4. Structure-contour map of the Mattaponi Formation In pocket 5. Structure-contour map of the Nanjemoy Formation In pocket 6. Structure-contour map of the Calvert Formation .... In pocket 7. Isopach map of the "transitional beds" In pocket 8. Isopach map of the Mattaponi Formation .....,........ In pocket 9. Isopaeh map of the Nanjemoy Formation .............. In pocket 10. Isopach map of the Calvert Formation In pocket 11. Correlation of selected wells ......... ....... In pocket Frcunn 1. Index map showing location of area of study 2. Inferred stratigraphic relationships among Yorktown lithologic types 30 TABLES 1. Geologic formations in the Coastal Plain of Virginia.......... 10 2. Comparison of the stratigraphic units used in this re- port with those previously used in the Coastal Plain of Virginia L2 STRATIGRAPHIC UNITS OF THE LOWER CRETACEOUS THROUGH MIOCENE SNRIES By Robert H. Teifke ABSTRACT The Coastal Plain of Virginia is divided into six rock-strati' graphic units of Cretaceous through Miocene age-the Patuxent, "transitional beds," Mattaponi, Nanjemoy, Calvert, and York- town formations. Each is a mappable unit whose stratigraphic boundaries can be determined from well cuttings using lithologic criteria. The subsurface configuration of the formations is shown in a series of five structure-contour and four isopach maps. The petrologic characteristics and external form of the Pa- tuxent Formation and "transitional beds" indicate a long period of active erosion and nonmarine sedimentation in which a thick sequence of terrigenous clastics was deposited, at first as a wedge of coarse feldspathic material (Patuxent Formation) and finally, with waning activity, as the finer sediments of the "transitional beds." Nonmarine sedimentation subdued the basement relief and set the stage for the marine transgressions that followed. The net effect of the first two transgressions, represented by the Mattaponi and Nanjemoy formations, was to obscure most of the features on the surface of the nonmarine terranes. By the end of Calvert time the surface of deposition had begun to re- semble the present surface. The Yorktown surface bears an even closer resemblance to the present topography. 6 VTRcINTA DrusroN or MrNnnal Rosouncns INTRODUCTION This report summarizes a geologic study of Cretaceous through Miocene rock-stratigraphic units in the Coastal plain province of Virginia between the Virginia-North Carolina boundary on the south and the,Potomac River on the north. and between the Fall Line on the west and Chesapeake Bay and the Atlantic Ocean on the east (Figure 1). From north to south, four major rivers flow southeastward to Chesapeake Bay: the Potomac, Rappahannock, York, and James, which divide the Coastal Plain into four areas commonly referred to as the Northern Neck peninsula, the Mid- dle peninsula, the York-James peninsula, and Southside Virginia. Figure 1. Index map showing location of area of study. The purposes of this paper are: (1) To describe and divide the sedimentary section in terms of easily determined and reproducible lithologic criteria applicable over wide areas. (2) To map the distribution and form of the rock-strtigraphic units in such a way as to provide a sound basis for future studies relating to such problems as basin evolution. (3) To construct a regional stratigraphic framework for projects of a more local nature. The stratigraphic section reported upon includes all strata be- tween the base of the Lower Cretaceous Patuxent Formation and the top of the upper Miocene Yorktown Formation. Rocks below Brm,prru 83 7 and above this interval are only briefly described in the text. Out- crop areas are shown on the maps for completeness, but all data that were utilized have been derived solely from boreholes. All drill cuttings that were examined are described in wpll logs on file at the Virginia Division of Mineral Resources. Numbers pre- ceded by the letter "W" (W-2109) designate wells whose samples are on file in the Division's repository; the locations of the wells are shown on Plate 1. Detailed logs of representative wells, and summaries of all others which were used in preparing this report, are included in Appendices I and II. MPTTTOIS OF INVESTIGATION From the well cuttings and core repository, samples from 126 boreholes on file as of January 2L,1972 werc chosen as the basis for this report. Selection was made on the following considera- tions: (1) maximum geographic distribution, (2) uniformity of coverage, (3) total depth of well and number of formations pene- trated, (4) quality of samples, and (5) degree of preeision with which well locations and elevations could be determined. The wells include 86 water wells, most of which were submitted by four drilling firms-sydnor Hydrodynamics, Inc. of Richmond, Mitchell's Well and Pump Co. of Colonial Heights, Pittman's Wood & Metal Products Co. of Courtland, and Douglas and Dick- inson, Inc. of Warsaw; 27 United States Geological Survey test holes; six Virginia Division of Mineral Resources test holes; and seven others. The geographic locations and surface elevations of the wells were determined at the well sites using the latest 7.5-minute topographic maps. Sample descriptions were based mainly on examination of both washed and unwashed well cuttings with the binocular microscope. The petrographic microscope was used to verify the presence of diatoms, and to determine the amount and type of feldspar in a given sample. Sulfates, phosphates, iron oxides and hydroxides, and dolomite were identified in some instances by combinations of optical and X-ray diffraction tech- niques. A base map (Plate 1) was drawn showing distribution of con- trol, lines of section, the Piedmont-Coastal Plain boundary (the Fall Line), counties, and a few cities. Well locations initially were plotted on an overlay, and at each well, elevations of the following were posted: (1) grouncl level, (2) formation tops, 8 VrR.crNrA DrvrsroN or MrNnnRr, Rosouncns and (3) total depth. These data, summafized, in Appendix I, were used to construct subsurface maps showing the areal distribution and three-dimensional configuration of the units. Five structure-contour maps (Plates 2-6) were drawn, and four isopach maps (Plates ?-10) were constructed by overlaying appropriate structure-contour maps. Sample cuttings are nor- mally recovered every 10 feet, so resolution of thinner intervals involves some interpretation. A 20-foot contour intervar was chosen for the maps as the optimum interval to show desired de- tail consistent with this sampling frequency. Using the method described by LeRoy and Low (1954, p.207-209) thickness values are determined not only at the wells but also at every point where contour lines on the structure maps intersect. This results in the generation of many secondary control points that permit thickness mapping in areas of litile or no welr control. Thickness variation, arrived at by this method, is interpretive only to the degree that the structure maps themselves are interpr,etive. Each structure contour and isopach map incorporates only those data points pertaining to that map.