STRATIGRAPHIC NOMENCLATURE AND GEOLOGIC SECTIONS OF THE GULF COASTAL PLAIN OF TEXAS By E.T. Baker, Jr. U.S. GEOLOGICAL SURVEY Open-File Report 94-461 A contribution of the Regional Aquifer-System Analysis Program Austin, Texas 1995 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. For additional information write to: Copies of this report can be purchased from: U.S. Geological Survey Earth Science Information Center District Chief Open-File Reports Section U.S. Geological Survey Box 25286, Mail Stop 517 8011 Cameron Rd. Denver Federal Center Austin, TX 78754-3898 Denver, CO 80225-0046 CONTENTS Abstract ............................................................................................................................................^ 1 Introduction .......................................................................................................................,........,............................^ 1 Stratigraphic Nomenclature ................................................................................................................................................. 1 Geologic Sections ................................................................................................................................................................. 2 Selected References ........................................................................................................................^^ 3 PLATES [Plates are in pockets. Plates 1-8 at reduced scale also are included as figures 2-9.] 1-8. Geologic sections: 1. A-A', Hunt County to Jefferson County, Texas, and offshore. 2. B-B1, Williamson County to Brazoria County, Texas, and offshore. 3. C-C1, Bexar County to Aransas County, Texas, and offshore. 4. D-D1, Maverick County to Kleberg County, Texas, and offshore. 5. E-E', Zapata County to Atascosa County, Texas. 6. E'-E", Atascosa County to Lee County, Texas. 7. E"-E'", Lee County to Sabine County, Texas. 8. F-F, Houston County to Cass County, Texas. FIGURES 1. Index map of Texas showing location of Gulf Coastal Plain, study area, and geographic subareas .................... 9 2-9. Geologic sections: 2. A-A', Hunt County to Jefferson County, Texas, and offshore ................................................................... 11 3. B-B1, Williamson County to Brazoria County, Texas, and offshore ......................................................... 13 4. C-C', Bexar County to Aransas County, Texas, and offshore ................................................................... 15 5. D-D', Maverick County to Kleberg County, Texas, and offshore ............................................................. 17 6. E-E', Zapata County to Atascosa County, Texas ....................................................................................... 19 7. E'-E", Atascosa County to Lee County, Texas .......................................................................................... 21 8. E"-E"', Lee County to Sabine County, Texas ............................................................................................ 23 9. F-F, Houston County to Cass County, Texas ........................................................................................... 25 10. Chart showing Stratigraphic nomenclature of the Gulf Coastal Plain of Texas .................................................... 27 11. Map showing section lines and wells used for control in study area ................................................................... 29 TABLE 1. Geologic-section wells used for control ............................................................................................................... 30 CONVERSION FACTORS AND VERTICAL DATUM ________________Multiply______________By_____________To obtain______________ foot (ft) 0.3048 meter mile (mi) 1.609 kilometer square mile (mi2) 2.590 square kilometer Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929. CONTENTS Hi Stratigraphic Nomenclature and Geologic Sections of the Gulf Coastal Plain of Texas By E.T. Baker, Jr. Abstract that included only the Coastal Plain sediments of Ter­ tiary and younger age in all or parts of 10 states (Grubb, Geologic sections showing the subsurface 1984). The geologic sections in this report also include delineation of approximately 100 Stratigraphic thousands of feet of Cretaceous rocks in Texas that units composing the Mesozoic and Cenozoic Eras were studied by the Edwards-Trinity RASA (Bush, illustrate the interrelation of these units across 1986). The Gulf Coastal Plain of Texas, the study area, most of the Gulf Coastal Plain of Texas. The geo­ and the geographic subareas are shown in figure 1 (at logic names that constitute the nomenclature have end of report); the geologic sections are presented as been published, and the vast majority are approved figures 2-9 (at end of report) and also are duplicated in larger form as plates 1-8 in the pocket in back of this for use by the U.S. Geological Survey. Four dip report. sections and four strike sections, extending from Geologic sections, type logs of oil fields includ­ the land surface to a maximum of about 18,000 ing faunal occurrences, and field reports by the Corpus feet below sea level, provide continuity of correla­ Christi Geological Society, East Texas Geological tion from the outcrop to the deep subsurface. Society, Houston Geological Society, South Texas Stratigraphic units containing water with less than Geological Society, Gulf Coast Association of Geolog­ 3,000 milligrams per liter concentration of dis­ ical Societies, and Bureau of Economic Geology were solved solids are shown on the geologic sections useful for identifying geologic contacts and correlating and serve as an indicator of water quality in the deep subsurface formations. The geologic sections of Gulf Coastal Plain of Texas. Eargle, Dickinson, and Davis (1975) were used to iden­ tify near-surface formations in parts of South Texas. INTRODUCTION The author wishes to express his appreciation to Lawrence W. Epps and George Slone of Mobil Explo­ This report presents the Stratigraphic nomencla­ ration and Production, U.S., Inc., Charles D. McMur- ture and illustrates the subsurface geology with geo­ rey of Hamill Resources, Inc., and Oliver Gross of logic sections for approximately 90,000 mi2 of the Gulf Exxon Co., U.S.A., Houston, Texas, for discussing cor­ Coastal Plain of Texas. That part of the subsurface con­ relation problems; to J. Rogers Pearcy, Jake Lowen- taining water with less than 3,000 mg/L (milligrams haupt, and Robert G. Zainey of the U.S. Minerals per liter) concentration of dissolved solids also is Management Service, Metairie, Louisiana, for provid­ shown on the sections. The many lithologic changes ing information on faunal occurrences in offshore drill within Stratigraphic units downdip and along strike, holes; to Saul Aronow, Lamar University, Beaumont, with attendant changes in nomenclature, have caused Texas, for discussing up-to-date research on the Qua­ problems in identifying and correlating the units ternary System offshore; and to Virgil E. Barnes, Uni­ problems which this report attempts to mitigate. This versity of Texas at Austin, Bureau of Economic report is a contribution of the U.S. Geological Survey's Geology, for contributing the latest geologic maps. Regional Aquifer-System Analysis (RASA) program to investigate regional ground-water systems nation­ STRATIGRAPHIC NOMENCLATURE wide. More specifically, the purpose of this report is to present geologic sections showing the geologic frame­ Stratigraphic nomenclature of rock units under­ work of the Texas part of the Gulf Coast RASA, a study lying the Gulf Coastal Plain of Texas is complex. This Abstract 1 is attributable to multidirectional changes in lithology Nueces (Lozo and Smith, 1964), Kainer (Rose, 1972), of many of the time-stratigraphic units across a geo­ and McKnight (Imlay, 1945) Formations, and Regional graphical area some 500 mi long and a few hundred Dense Member (Rose, 1972) of Fredericksburg Group; miles wide. A secondary factor is the many thousands Edwards Group (Rose, 1972) of Comanchean Series; of feet of sediment in the Gulf Coast geosyncline that Person Formation (Rose, 1972), Salmon Peak Forma­ have been differentiated over the last century into tion (Lozo and Smith, 1964), and Maness Shale numerous stratigraphic units. This differentiation was (Bailey, Evans, and Adkins, 1945) of Washita Group; mainly the result of extensive drilling by the oil indus­ Vicksburg Group (Cooke, 1923) of Oligocene Series; try, which opened up progressively deeper parts of the and Anahuac Formation (Ellisor, 1944) of Oli- subsurface to study and to subsequent separation into gocene(?) or Miocene Series. These informal geologic identifiable and mappable units. names are italicized in the chart of stratigraphic Stratigraphic units applicable to the Gulf Coastal nomenclature (fig. 10) to distinguish them from the for­ Plain of Texas are presented in figure 10 (at end of mal names approved by the U.S. Geological Survey. report). These units constitute the Mesozoic and Ceno- zoic Erathems and include sediments of the Quaternary GEOLOGIC SECTIONS