REVISION OF COMANCHE STRATIGRAPHIC NOMENCLATURE, SOUTHERN EDWARDS PLATEAU, SOUTHWEST

F. E. LOZO1

C. I. SMITH1

ABSTRACT

The Devils River Formation and correlative Lower Cretaceous rock units in the southern Edwards Plateau of Texas are divisible into three geologically distinct areas on the basis of different facies developments. These are referred to as northern, central, and southern areas, and the stratigraphic nomenclature is revised accordingly. The northern area sequence, regionally characterized by ammonite-bearing marly mudstones changing facies southward into rudist-miliolid , is divisible by a dis- confonnity into two formations. New names are under consideration pending additional fieldwork. The central area sequence, assigned to the Devils River Formation proper and con­ fined to a narrow band encircling the southern or Maverick basin area, is represented by the combined and undivided rudist-miliolid limestones of the northern units. Udden's con­ cept of the stratigraphic interval is retained, but the area of application is restricted. The southern area sequence is marked by the abrupt southward facies change of the undivided Devils River carbonate section into the three units distinctive of the Maverick basin: a lower wackestone unit, the so-called "Edwards Formation;" the evaporitic "Kia- michi Formation" (also called McKnight); and an upper lime mudstone unit previously identified as the "." Suppression of the older names is advocated, and replacement nomenclature is proposed.

INTRODUCTION A regional synthesis of the Edwards Plateau Cre­ taceous requires a regional approach plus a system In the years since Adkins (1933) summarized of nomenclature that reflects- significant geographic the Mesozoic stratigraphy of Texas, data on the and geologic distinctions. This contribution is based Cretaceous of southwest Texas have increased enor­ on such a study, in the course of which the im­ mously. Most of the information has come from propriety and ambiguity of the older terminology progressively deeper downdip drilling for oil and have been thoroughly explored. In view of the plans gas, and the basic relationships comprising the re­ of The University of Texas Bureau of Economic gional stratigraphic framework in the subsurface Geology cooperative project for the 1:250,000 geolo­ have become generally known. The adjoining out­ gic atlas of Texas, it is timely that proposals perti­ crop, on the contrary, has but recently received nent to mappable units be submitted. comparable attention, and the tie between the sur­ face and subsurface has long remained obscure, at Previously used formation names, evaluated in least in detail. the light of present information, are recommended Outcrop geologic studies of recent date in the for replacement, emendation, or formal acceptance, southern Edwards Plateau region (Figure 1) have and the rock unit names selected are defined in ac­ been principally for two purposes: (a) hydrologic cordance with the Code of Stratigraphic Nomencla­ ture. The initial section treating the basis for revi­ investigations programmed as a result of the 1947- 1 1957 drought, and (b) structural mapping for sur­ sion is the responsibility of F. E. Lozo . The section face anomalies coincident with deep gravity, mag­ on descriptive stratigraphy is to be credited to C. netic or other geophysical prospects. In both cases, I. Smith, who did the field work, certified the stra­ the areal extent of individual studies was generally tigraphic relationships, and selected the names. The local (county-size or less), and the stratigraphic no­ geologic map (Figure 15, in color) was printed and menclature of the outcrop units was of little concern donated by Shell Development Company, Explora­ — usage consistent with earlier works was accept­ tion and Production Research Division, Houston, able. Neither of these types of investigation auto­ Texas. matically resolves regional stratigraphic relation­ BASIS FOR REVISION ships, and in neither type is the local propriety of formation names a matter of question. Historical Background of Cretaceous Studies 'Shell Development Company (A Division of Shell Oil Compa­ The Comanche Cretaceous of southwest Texas has ny), Exploration and Production Research Division, Houston, been studied much less than that of northeast Tex­ Texas. Publication No. 383. as, principally because of the differences in geologic 'This paper is coauthored, and no seniority is to be implied in the order of names. F. E. Lozo. setting. The southeastward-flowing 285 286 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

103° 102° 101° 100° M' 98 97 Figure 1. Physiographic diagram of Edwards Plateau and adjoining regions; area .of investigation outlined. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 287 divides the continuous outcrop belt in Texas into of names by all previous investigators have been two large and geologically distinct regions: (a) To critically examined and tabulated geographically the north and east of the river are cuesta-type prai­ (Figures. 3, 4, and 5) by areas now known to be ries and timbered terrains underlain by limestones, geologically distinct (Figure 6). It is evident that marls, and sands, with terrigenous elastics increas­ local formation names from southwest Texas (Devils ing northward, (b) To the south and west is a more River, Del Rio), from central Texas (Edwards, extensive, elevated, marginally dissected tableland Georgetown, Buda), and from north Texas (Walnut, dominated by limestones — the Edwards Plateau Comanche Peak, Kiamichi, Grayson) have been in­ and its trans-Pecos extension, the Stockton Plateau. consistently applied and mixed as convenience and personal judgment dictated. The fact that the same The outcrop north of the Colorado is the historical­ inconsistency and ambiguity occur, not only within ly significant and classic study area of the Comanche each area but also from area to area, supports some Cretaceous. The pioneer work to elucidate the stra- effort toward uniformity. tigraphic sequence, the faunal succession, and other salient geologic relationships was concentrated here, In general, three basic approaches have been used and, as a consequence, the type sections and name­ to classify the southwest Texas Cretaceous sequence sake localities of most of the formations of the pro­ above the Glen Rose, or basal sand, and below the vincial lower series of the Cretaceous are within Del Rio or Buda, where the Del Rio is missing. The this area. oldest, most commonly used, and most objectionable method follows the premature application by Hill The area southwest of the Colorado River, in con­ and Vaughan (1898a,b) of north and central Texas trast, has received much less intensive study, and formation names to presumed equivalents; these basic stratigraphic relationships have remained un­ names and misconceptions were extended directly certain. The relative disparity in quality and quan­ into the subsurface sections. The next most com­ tity of data is due to lack of favorable exposures on mon, but opposite, approach follows the assignment the extensive upland areas of the Edwards Plateau, by Udden (1907) of the total section to a single greater structural complexity, and a lithologic se­ formation, the Devils River ; the imprac- quence dominated by limestone with few marker ticality of subdivision is implied. The latest of the beds or contrasting lithologies. To these basic attri­ approaches follows the reference of Petitt and George butes or complications have been added problems (1956) to the entire section as "Edwards and asso­ of nomenclature; the names applied (Figure 2) ex­ ciated limestones" with lettered "zones" approximat­ tended largely from the northeastern area, have long ing the rock units of north and central Texas. This been ambiguous and misleading in attempts to re­ nonformal system has been adopted by ground-water late the stratigraphy properly. hydrologists who treat the total interval as a single

TIME-ROCK UNITS ROCK UNITS aquifer and as an indivisible hydrologic unit; in Standard Provi nc ia1 Central Texas concept the classification is a mixture of that of Ud­ Sequence Sequence Format ions den with that of Hill and Vaughan. BUDA It is significant to point out that all of these basic approaches to classifying and naming the rock units UPPE R „ DEL RIO T A CRETACEOU S CENOMANIA N have been applied in each geologically distinct area 1 H ( Main Street ) and that none has proved generally acceptable. A detailed account, author by author, of the progres­ u,

COMANCHE PEAK consideration, have one result in common — over­ L B 1 A N

A extension of rock unit names. This objectionable FREDERICKSBUR G WALNUT E T A C 0

R practice is due essentially to nonrecognition of fa­ H E C R T A ° o GLEN ROSE des relationships, locally and regionally.

HENSEL Evaluation of Nomenclature COW CREEK 3 z For purposes of cartographic representation, in­ HAMMETT OMA N •E telligible description, and historical interpretation, the unsound usage of certain old names' should be SYCAMORE suppressed, other names can be retained with more

NEOCOMIA N precise definition, and some new units must be de­ fined and named. It is to be remembered that lithic Figure 2. Sequences of stratigraphic units, central Texas; in­ terval and names concerned within the outlined units and names are in no sense absolute and can portion. be abandoned, redefined, revived, or accepted as utility indicates. The bases for the proposed changes Summary of Previous Investigations 'For synopsis or digests of the previously named units, see Ad­ In the course of this study, the various concepts kins (1933), Wilmarth (1938), Adkins and Lozo (1951), and of the rock units from area to area and the usage Lozo (1959). 288 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

A. Drainage Basins of ond Devils River References

Calcareous Group ( = Upper Cretaceous ) Shumard [1855-56], 1886

DEVILS RIVER LIMESTONE DEL RIO BUDA Udden, 1907

DEVILS RIVER LIMESTONE DEL RIO 611 DA Udden, Baker and Bose, 1916

DEVILS RIVER LIMESTONE DEL RIO DUDA Roberts and Nash, 1918

UAI "„Z 1 DEVILS RIVER LIMESTONE 1 GEORGETOWN DEL RIO BUDA Christner and Wheeler, 1918 NUT , (

WALNUT and EDWARDS LIMESTONE \ =: Liddle and Prettyman, 1920 :0MANCHE PEAK Division! [Division 2 | Division 3 y

DEVILS RIVER LIMESTONE DEL RIO BUDA Calvert, 1928 Key bed — •

WAL­ COMANCHE PEAK EDWARDS GEORGETOWN ? DEL RIO ? Fritts, 1933 NUT

EDWARDS GEORGETOWN DEL RIO BUDA Dartoti, 1933

DEVILS RIVER DEL RIO BUDA Stanton, 1947 (also 1928) ( = Georgetown age )

[ numbered beds - no formation names applied ] , Edson, 1951

DEVILS R IVER LIMESTONE DEL RIO BUDA Spice, 1954 Member 1 Member 2 j Member 3

Lozo and Smith, 7964 Unnamed Lower Formation Unnamed Upper Formation DEL RIO BUDA this report

B. Edwards Plateau Divide: Latitude of Roclcsprings - Fredericksburg

Kreide des Hochlandes ( = Turonian - Senonian ) Roemer, 1849, 1852

COMANCHE PEAK EDWARDS FORT WORTH DEL RIO Hill and Vaughan, 1898 a-b

COMANCHE PEAK EDWARDS GEORGETOWN DEL RIO BUDA Curry, 1933, 1934

WALNUT and Barnes, 1944, 1952-56 COMANCHE PEAK Kirschberg evaporite — I Y ==

EDWARDS and Assoc ated Limestones GRAYSON BUDA Long, 1962 Zone A j Zones 6 and C Zone D

Loio and Smith, 1964 Unnamed Lower Formation Unnamed Upper Formation DEL RIO BUDA this report

Figure 3. Chart of comparative nomenclature of Fredericksburg and Washita units applied in northern area of Figure 6, 1849- 1964.

Central Vol Verde County East to Southern Real County

COMANCHE PEAK EDWARDS LIMESTONE Hill and Vaughan, 1898 a-b

DEVILS RIVER LIMESTONE Udden, 1907

COMANCHE PEAK EDWARDS LIMESTONE GEORGETOWN LIMESTONE Curry, 1933, 1934

EDWARDS and Associated Limestones COMANCHE PEAK I EDWARDS ? GEORGETOWN Long, 1958 Zone A j Zone B | Zone C | Zone D

FREDERICKSBURG GROUP ? WASHITA GROUP COMANCHE PEAKl [ beds indicated by footage above base ]

EDWARDS and Associated Limestones Gulf Coast Association Geological Societies, 1961 COMANCHE PEAKl EDWARDS ? Kki ? GEORGETOWN

DEVILS RIVER LIMESTONE Rodda and Fisher, 1961

EDWARDS and Associated Limestones COMANCHE PEAKl EDWARDS and GEORGETOWN Long, 1962 Zone A Zone C I Zone D

L020 and Smith, 1964 DEVILS RIVER LIMESTONE this report

Figure 4. Chart of comparative nomenclature of Fredericksburg and Washita units applied in central area of Figure 6, 1898-1964. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 289

A. Vol Verde County References

DEVILS RIVER LIMESTONE ! t - *9t 1

DEVILS RIVER LIMESTONE Udden, Baker and Bose, 1916

DEVILS RIVER LIMESTONE Roberts and Nash, 1918

DEVILS RIVER LIMESTONE Calvert, 1928

DEVILS RIVER LIMESTONE Stanton, 1928

EDWARDS LIMESTONE ? GEORGETOWN Oarton, 1933 I

DEVILS RIVER LS. [ - Kgt ] Stanton, 19^7

DEVILS RIVER LIMESTONE Cheetham, 19^9

International Boundary and EDWARDS LS COMANCHE PEAK - KIAMICHI FM. GEORGETOWN LIMESTONE Water Commission, 1955

GEORGETOWN LIMESTONE Hazzard, 1956, 1959

Loio and Smith. 1964 WEST NUECES FORMAT/ON McKNIGHT FM. SALMON PEAK FORMATION this report

B, Uvalde and Kinney Counties

SHOAL COMANCHE PEAK EDWARDS LIMESTONE FORT WORTH DEL RIO Hill and Vaughan, 1898 a-b CREEK LS.

COMANCHE PEAK EDWARDS LIMESTONE FORT WORTH DEL RIO Vaughan, 1900 a

DEVILS RIVER LIMESTONE DEL RIO BUDA Udden, 1907

COMANCHE PEAK EDWARDS LIMESTONE GEORGETOWN DEL RIO 8UDA Getzendaner, 1931

WALNUT and EDWARDS LIMESTONE GEORGETOWN DEL RIO BUDA Sayre, I936 COMANCHE PEAK

KIAMICHI FM. EDWARDS FORMATION GEORGETOWN LIMESTONE GRAYSON BUDA imlay, 19*t5 [subsurface] [-"McKnight"]

[unknown at COMANCHE PEAK EDWARDS DEVILS RIVER LIMESTONE GRAYSON BUDA Stanton, 19I17 [outcrop] surface] = GE — =^^ °™ GRAYSON BUDA Greenwood, 1956

EDWARDS and Associated Limestones GRAYSON BUDA Petitt and George, 1956

EDWARDS an I Associated L mestones GRAYSON Welder and Reeves [1955-57] Zone A Zone B Zone C Zone D [= "Whitecap" Is.] BUDA (DEL RIO) (preliminary field terms) nodular Is. llower massive Is. flaggy Is. upper massive Is. F EDERICKSBURG GROIJ P nodular Is. GEORGETOWN LIMESTONE GRAYSON BUDA Park, 1959 and clay (Kwa) lower massive Is. fIaggy 1s .

KIAMICHI GRAYSON or Gulf Coast Association COMANCHE PEAK EDWARDS GEORGETOWN BUDA or "MCKNIGHT" DEL RIO Geological Societies, I96I

COMANCHE PEAK EDWARDS KIAMICHI GEORGETOWN GRAYSON BUDA Welder and Reeves, 1962

EOWARDS FORMAT ON GEORGE­ COMANCHE PEAK GRAYSON BUDA Bennett and Sayre, 1962 Zone 1 Zone 2 Zone 3 IZone h|Zone 5 TOWN

L010 and Smith, 1964 WEST NUECES FORMATION MCKNIGHT FM. SALMON PEAK FORMATION DEL RIO SODA

Figure 5. Chart of comparative nomenclature of Fredericksburg and Washita units applied in southern area of Figure 6, 1895-1964. 290 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964 are summarized below; the formation units herein to the east, the exposures along the Devils River are recognized have been tested and have proved to be limited to the upper portion of the section between adequate for the purposes stated. the Glen Rose and Del Rio formations. Although in­ dicating a general correlation with the (erroneous) Suppressed (Restricted) Names Georgetown and Edwards of Hill and Vaughan, Ud­ These names, (Figure 5), quite valid for central den stressed the uncertainty of his correlations and and (or) north Texas rock units, are considered in­ the impracticality of subdividing the section at this appropriate for usage in southwest Texas. stage of reconnaissance, and he introduced the term Devils River. The name has been generally used WALNUT (Hill, 1891) and (or) COMANCHE since, in all areas, to refer to the entire and undivid­ PEAK (Hill, 1891). Either or both of these names ed section below the Del Rio and above the Glen have been applied to the nodular limestone at the Rose. This concept is useful in a much narrower base of the section under discussion. Usually asso­ area than previously applied and, as restricted in ciated with Exogyra texana Roemer and other mol- this report (to the central area only), is both mean­ lusks, and widespread and persistent as a basal ingful and appropriate. transgressive lithofacies, the unit has not been se­ curely mapped or traced as a continuous body into DEL RIO (Hill and Vaughan, 1898) and BUDA the type Walnut or Comanche Peak units of north- (Vaughan, 1900). Normally overlying the Devils central Texas. River or equivalent strata are dark clays with thin, flaggy, shelly, or arenaceous beds, the type Del EDWARDS (Hill and Vaughan, 1898) and Rio. The Geologic Names Committee of the U. S. GEORGETOWN (Hill, 1901). Although derived in Geological Survey have favored the usage of Gray­ name from the Edwards Plateau, the Edwards For­ son (Cragin, 1894) over Del Rio, but the facies dif­ mation was thoroughly misconceived in the name­ ferences and other distinctions between the marly sake area at the time of substitution of the name north Texas formation and the type Del Rio are "Edwards" for the paleontologically designated "Ca- considered more valid than priority in retaining prina limestone." Hill and Vaughan's generalized the name Del Rio (cf. Adkins and Lozo, 1951, pp. section from the Nueces and Uvalde quadrangles is 114, 153). With respect to the Buda, the name has a composite section based on observations from parts been consistently applied in southwest Texas by all of all three of the geologically distinct areas of this workers. report. The so-called "Edwards" of the southern Ed­ wards Plateau is misleading as to lithic character Provisional and New Names and grossly inaccurate as a tabular rock unit correla­ These names, defined in accordance with the Code tive of the type Edwards of central Texas. Projec­ of Stratigraphic Nomenclature, are the WEST NUE­ tion of the term Edwards (as with the Comanche CES, McKNIGHT (Winter, 1961), and SALMON Peak and Walnut), solely on a homotaxial basis, PEAK formations in the southern area. No type through an intermediate area of complex structure section or type well of the McKnight has yet been and stratigraphy was questionable in principle ori­ designated; an outcrop reference section is presented. ginally and has proved unsound in practice ever The regional relationship of these units and the since. The basic objections to the Edwards as a valid Devils River Formation is diagrammed in Figure 7. unit in southwest Texas also apply to the so-called "Georgetown." Even more atypical with respect to DESCRIPTIVE STRATIGRAPHY the physical attributes of the type section, the name has been retained mostly by association with the Geologic Setting and General Relationships name Edwards. The standard section of the outcrop Comanche Cretaceous in central Texas is shown in Figure 5. KIAMICHI (Hill, 1891). The unwarranted sub­ This report is concerned with that portion of the stitution (Imlay, 1945) of the name Kiamichi for column within the shaded border. None of the for­ the then-informal "McKnight" evaporite-bearing, mation names shown in this interval is currently dark "shale" section in the subsurface was erroneous­ considered applicable in the Edwards Plateau region ly predicated on lateral continuity of the Kiamichi because of facies changes and considerations of from north Texas into southwest Texas; the name stratigraphic propriety. However, the bounding for­ was subsequently extended to the outcrop in Uvalde mations — Glen Rose' and Del Rio — have the County by the U. S. Geological Survey (Welder and same facies here as in central Texas, and the con­ Reeves, 1962). The southwest Texas unit is now tacts between them and the interval studied are known to be. completely separate from, and geolo­ considered to be time-stratigraphic horizons as well gically unrelated to, the type Kiamichi (southeastern as lithologic boundaries. Oklahoma); neither facts nor logic supports reten­ Interpretations of physical features of upper Glen tion of usage in the embayment area. Rose beds in the southeastern part of the study area indicate that during this time lime muds, now re­ Retained Names presented as dolomitized mudstone1, were deposited DEVILS RIVER (Udden, 1907). As in the case of in the littoral zone and immediately offshore while Hill and Vaughan's studies to the east, Udden's ob­ lime wackestones with normal marine fauna were servations to the west were from all three of the 'Carbonate rock classification in this report follows Dunham distinct areas of the present report. Unlike the area (1962). LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 291 being deposited farther offshore. At the end of Tri­ Definition of Rock Units nity (Glen Rose) time the shoreline had withdrawn to a position parallel to and slightly north of the On the bases for revision summarized in the ini­ Balcones fault trend. The shore area and an ex­ tial section of this report, a revised system of no­ panse some distance inland was an exposed mud menclature appropriate for the central and southern areas is submitted below2. The formation units re­ flat undergoing consolidation, cementation, and wea­ cognized are of tested utility for descriptive and thering. Farther inland and westward fluvial sands, cartographic purposes (Figures 9-15) ;3 the names silts, and redbeds were being deposited. proposed and the usages advocated should suppress As the sea readvanced to the north, offshore lime certain ambiguities and thus advance sounder in­ wackestones with normal marine faunas were de­ terpretations of the geologic history of the region posited in the following sequence: (1) transitional- concerned. ly on dolomite and dolomitic marls; (2) disconform­ ably on bored, oyster-encrusted, and weathered dolo­ Devils River Formation (Udden, 1907) mite; and (3) transitionally to locally disconform- Udden introduced the name Devils River ably on sands and silts. These initial transgressive Limestone in these words: sediments, a nodular lime wackestone varying from 10 to 60 feet thick, form a basal rock unit common "This name is here applied to the lime­ to most of the study area. It may be desirable to stones which are found exposed on Devil's designate the unit formally in the future, but for 1 River (Val Verde County). They include the present this seems unnecessary . what is known in central Texas as the Ed­ wards and Georgetown limestones. The up­ These basal beds and the overlying 500-700 feet per hundred feet, or less, correspond to the of limestones can be divided geographically into latter, and the lower four hundred feet are three geologically distinct areas — northern, central, the equivalent of the greater part of the and southern (Figure 6) — and the rocks in each former. They are not separated by any area are divisible into distinct formations (Figure well-marked horizon of change, but merge 7). The northern area sequence, divisible by a dis- gradually into each other." conformity into two formations, is characterized by ease of subdivision, by distinctive faunal assemblag­ The errors of the conjectured footage equivalents es, and by a north-south facies change from marly of this date (extended directly from the assumptions mudstones to predominantly rudist-miliolid wacke­ of Hill and Vaughan (1898) on the Edwards Plateau stones. The southward facies change culminates in section to the east); the fact that essentially all of a narrow band of undivided rudist-miliolid lime the exposed section observed by Udden is of Washi­ wackestones, mudstones, and minor grainstones ta age (noted earlier by Dumble (1895) and stressed which constitute the central area. The boundary subsequently by Stanton (1928); and the observa­ between the central and southern areas is a line of tion that Udden applied the name to exposures from abrupt facies change from the single mass of indi­ old Camp Hudson (Figure 6), north of the outcrop visible limestones to three formations of variable trend as now restricted, downstream to the Rio limestone facies (Figure 8). This line of facies Grande, quite some distance south of the restricted change marks the northeastern boundary of the trend, have not affected the basic concept of the Maverick basin (Winter, 1961a-c), and the three for­ Devils River Limestone. The concept of an undivided mations are characteristic of this basin. formation predominantly of Edwards facies but re­ presenting all of the Fredericksburg formations plus The upper contact of this" group of closely in­ the overlying Georgetown Washita of central Texas terrelated formations is a major unconformity ex­ has remained useful, has been consistently so ap­ hibiting both truncation of the underlying beds and plied, and can be retained with slight modification. two separate onlaps of the overlying formations, the Del Rio and the Buda. In the southern area, The data pertinent to redefinition of the Devils 80-90 feet of Del Rio clays plus a basal 30 feet of River Formation are given below: inter-bedded clay and limestone overlies the uncon­ formity. Northward these beds thin by onlap and Formal reference. Udden, J. A. (1907), Report truncation. Beyond the onlap-plus-truncation limit on a Geological Survey of the Lands Belonging to of the Del Rio, the Buda Limestone rests on the un­ the New York and Texas Land Company (Ltd.) in conformity, and this relationship is present over the Upper Rio Grande Embayment in Texas, Augus- most of the northern area investigated. tana Library Pub. No. 6, p. 56.

'This unit has been mapped by previous workers as the "Co­ manche Peak" or "Walnut-Comanche Peak" formation. For Name and geographic feature. Devils River Lime­ reasons stated in the Revision of Nomenclature section, it is stone, after exposures along Devils River, Val Verde not desirable to use either of these names in this area. Fur­ County, Texas. thermore, as the basal transgressive beds of several formations, the unit is an integral part of these formations, and designa­ tion as a separate stratigraphic unit serves to obscure rather 'Figure 15 is based on the works of Hill and Vaughan than clarify this relationship. (1898a-b,), Vaughan (1900a), Long (1958, 1962), Welder and Proposals treating the northern area are withheld pending Reeves (1962), and Bennett and Sayre (1962) with additional additional field work. mapping by the writers. 292 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

0 10 30 30 40 SO

Figure 6. Map of geologically distinct areas in the Edwards Plateau; area of study outlined.

NORTHERN AREA CENTRAL SOUTHERN AREA AREA Leakey Fort Lancaster B UD A DEL RIO

Upper Regressi' <

UNNAMED UPPER SALMON DEVI LS < FORMATION PEAK

FORMATION

RIVER <

MC KNIGHT

FORMATION UNNAMED LOWE R FORMATION > < WEST FORMATION > < NUECES > FORMATION

Basal Sands

GLEN ROSE

Figure 7. Generalized northwest-southeast stratigraphic section of Devils River Formation and equivalents, Edwards Plateau. ®- -®- FOnT TEMETT LEAKEY ROAD CUT

G FO i 1 rrr^T] rem 7~71 E^TOI __ _. Marl Mudtton* Wacktitan* Graimlon* Dolomit* kraccia Conglomerate Chert Estimated or retry ftalli red •vaportte tnkknoti limeitone

Figure 8. North-south correlation cross-section, southern Edwards Plateau, southwest Texas. 294 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

Hiliolid, Dictyoconos cf. D. walnutensis, shell fragment grainstone with Tow recrystallized and with large oysters in upper part

yiliolid. shell fragment grainstone; recrystal lized in upper 1 foot; recryit» 11ized and with Toucasia in lower 2 feet • bedded, miHo lid, shel 1 fragment, snail grains

Hiliolid mudstone with Toucasia, caprinidnids (?}\fI , and Monoplcura in mound; oyster and 130 14 Toucasia fragment mudstone with chert in int 15 Hiliolid, shell fragment, lilhoclast ([fainstone

14 Recrystallized and dolomitized limest e with fossi I mol Z 120 Shell fragment, i iliolid grainatone with small snails in lower 1 fo «frystat1ii?d LR-101 with chert and o Recryst» 1 1 iz«d limestone with large irregular chert masses and recrysta1 1 ized 12 of gray fine grain limestone in upper 4 feet; mottled, slender snail, oyster j]Q echinoid fragment waekes tone with abundant miliolids in lower 4 feet

buff, recrystallized and dolo

Oyster fragment, mottled wackestone with slender 1 foot 191^1 Thin-bedded to laminated shell fragment muds

od, echinoid fragment wa eke si tone in lower 1 foot; slende il, ostracod estone in upper 2 feet

Hottled [burrowed(?)], shell fragment, pellet wackestone with abundant small cla

'.ir. ^y^.^^y r 2 feet and mudst V • £- • --S • &- Hiliolid, shell fragment grai one with slende lithoclasts in upper 0.5 fo burrowed, mili in the middle; oys fragments throughout

5 Very poorly exposed.

4 Similar to below with .

> ; •> Ijj « c 3 Burrowed, nodular, shell fragment wackestone with Exofyr, o a -

3 Soft yellow break.

Poorly exposed, nodular, shell fragment wackestone th abundant E. tex.

GLEN ROSE

EXPL ANATION

s—< Exogyra texana ^> Radiolite ~\$r Burrowed

Marl Mudstone Wackestone Grainstone 1/ /I Breccia Chert or recrystallized Dolomite limestone Figure 9a Graphic section of the Devils River Formation at the type locality; 4 miles west of Leakey on State Highway 337, Real County, Texas. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS

Recrystallized 1 i m shell fragments, pellets, and in upper 2 feet.

Thin-bedded, completely recrystallized, fine gcain limestone with Urge crystals in beds and in vertical veins; becomes thin-bedded to laminated upward with caliche in upper mo st part 24.2

Z o 29 Recrystallized and calichified limestone;

a A „ -260

3 £?x+-< Dark gray, recrystallized, fi ontorted and brecciated upward; recrysta llized and dolomitized with angular holes where pie of breccia have been dissol ved in upper part; angular broken chert throughout.

Recrystal lized in lower half with remnant miliolids and shell fragments; chert with miliolid, shell fragment grainstone; top half calichified and dolomitized. ... 14.5

26 Recrystalliied and dolomitized li th clam and snai 1 molds

ystallized and dolomitized li th large, well preserved caprinids lower 1 foot

Dolomite with caprinid, snail, and clam molds; yellow, soft, friable dolomite in upper part

Dolomitized and reerystal 1 ized limes olds in upper 2 feet thin-bedded caliche in lower part.

Recrystallized and dolomitized lime stone with abundant small clam and gastropod molds; worm (?) tubes above large chert nodules near middle ggfy ^z:

WT^TW- Dolomitized «nd recrysta 1 1ized limestone with abundant snail molds; miliolid, 21 oyster fragment, lithc-clast (?) grainstone with abundant gastropods in upper 1 foot

20 Covered.

good ledge

Figure 9b Graphic section of the Devils River Formation at the type locality; 4 miles west of Leakey on State Highway 337, Real County, Texas. 296 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

SI Recryital liied limestoi

SO Toucaaia fragment, pellet wackestone with Toucaaia and Pecte

Miliolid, Toucaaia, and oyiter fragment £ rains tone with abundant Chondrodont 450 4' Toucasia, and Monopleura

fin* erain, recry*ta1lized limestone.

Shell fragment wackestone with abundant radiolites, caprinida, Fecfei Chondrodonta; one coral; calichified at ba«e; Toucasia at top

Z 44 Shell fragment wicktitone with abundant radiolitea, caprinids, oysters; radiolites * LR-<0 mostly broken in lower part, whole in upper part o 45 Ostracod, miliolid, pellet wackestone or mudstone with scattered oyster fragments. 3.5 I-

to

ui

5 Light gray, fine to coarse grsin, mottled, r*crystal 1 ized limestone with miliotids and shell fragments in chert; top 2.0 feet ostracod, shell fragment, pellet wackestone with abundant llonopleura and scattered caprinids 30.5

43 Recrystallised limestone with abundant oysters, clams, and Pecren.

42 Dense, recrystallized, fine grain limestone.

Recrystallized and calichified limestone with gastropods, clams, and remnant shell f ra gmen ts

___/"»n7iolid, shell fragment grainstone with abundant whole konopleura; one specimen 40 filled with pellets

-370 Recrystallized mudstone (?) with Toucaaia fragments and caprinida becoming more 39 abundant toward mound; flanking beds of shell fragment wackestone with abundant Mononteura, Toucaaia, and capcinids

38 Recrystallized limestone with remnant miliolids and fragments

oft, shell fragment wackestone with abundant gastropods, oysters, caprinids, and scattered Lunatia; highly burrowed and slightly nodular

Miliolid, shell fragment wackestone with abundant Toucaaia and MonopUura in upper SSg.r-•>••». 350 3* part; slightly recrystallized in lower part

35 Shell fragment grainstone with large Toucasia fragments

Shell fragment, miliolid, pellet (?) grainstone (?) with llonopleura and Toucaaia; 340 caprinid fragments common j,* 5'3

330 33 Recrystallized limeatone with local caprinid fragmen

ladiolite fragment wackestone with abundant pellets, Iithoc I asts , oys caprinida; recrysta 11ised and calichified in lower part

E 31 Described on preceding figure Figure 9a-c. Graphic section of the Devils River Formation at the type locality; 4 miles west of Leakey on State Highway 337, Real County, Texas. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 297

Type region (namesake area). No type section or west of the Laguna-Brackettville road crossing (State locality originally specified. By the Code (Art. 13i), Highway 334), immediately upstream from the con­ the type area contains the type locality, and the fluence with Chalk Creek, Chapman Ranch, north­ type locality contains the type section. Without eastern Kinney County. The locality (WN I & II, these, the original reference area — from Camp Figure 15) is about 8 miles north of Turkey Moun­ Hudson downstream to the Rio Grande — is actually tain and is two miles West 22° North of Salmon a namesake area only1. Peak on the U.S.G.S. Turkey Mountain quadrangle, 15-minute series, 1:62,500 scale. Type section and type locality. Here designated as the section exposed in roadcuts along the Camp Summary lithologic description. The type section Wood-Leakey road (State Highway 337), Real Coun­ is about 145 feet thick and is in sharp concordant ty, Texas, from about 4 miles west of Leakey to contact with the underlying Glen Rose. The lower the top of the divide. This is the maximum exposed 60 feet is the regional basal transgressive unit — interval — 447 feet of the 500- to 600-foot outcrop nodular, shell fragment wackestone with common total thickness — and the most accessible section in oysters and other molluscan — generally the trend. called Comanche Peak (cf. Bennett and Sayre, 1962, Type area. Extends from northern Uvalde County p. 19). The overlying 80-85 feet of massive bedded, through the type locality in southern Real County, miliolid, pellet, shell fragment wackestones to mud- and west through southern Edwards into the name­ stones with some grainstones is the so-called Ed­ sake Devils River drainage near the mouth of Dry wards where the overlying flaggy unit is referred Devils River (Figure 6). Outcrop belt is 10-15 miles to the Kiamichi (Welder and Reeves, 1962) Others wide, as defined by the limits of the subdivided se­ have referred informally to the upper West Nueces quences to the north and south. unit as the "first zone of the Edwards," to the flaggy unit as the "second zone," etc. (Bennett and Summary lithologic description and contacts. The Sayre, 1962). Leakey roadcut section (Figure 9a-c) has been described by Long (1958), Park (1959), Rodda and Area of application. Southerly from the type area, Fisher (1961), Welder and Reeves (1962) and is the West Nueces can be defined objectively over treated in the field trip guidebooks of the South most of southern Uvalde and Kinney counties Texas Geological Society, 1960, and the Gulf Coast by recognition of the basal nodular wackestone beds. Association of Geological Societies, 1961. The entire Beyond this limit in the subsurface the basal contact section is dominated by miliolid, pellet, rudist, shell is indefinite within a transitional interval, and the fragment lime grainstones and wackestones locally projected position of the West Nueces-Glen Rose dolomitized, brecciated, and chert-bearing; rudist contact over most of the Maverick basin is conjectur­ mounds and layers are more common in the upper al. In practice, the area of application is coincident portion. The basal nodular, fossiliferous wackestone with the limits of the overlying McKnight Forma­ is disconformable on the Glen Rose; the uppermost tion. beds (absent here) are in disconformable contact with the Del Rio to the west. McKnight Formation (Winter, 1961) Area of application. In southwest Texas, the out­ The name McKnight, first used informally by crop area of application extends from northwestern Hedwig T. Kniker in reference to the dark lime­ Medina County west through the type area to the stone with evaporites in the Paul Teas and Producers Rio Grande near the mouth of the Pecos River. In of Maryland Oil Co. No. 1 S. E. McKnight well, Mexico, the outcrop belt has been mapped by Petro- Dimmit County, Texas (Sandidge, 1946, and per­ leos Mexicanos across the Serrania del Burro (near sonal communication 10/28/61), was discarded as a Cerro El Colorado) and extended south through the synonym of Kiamichi by Imlay (1945). Later data Sierra del Carmen and Sierra de San Geronimo to­ are in disagreement with Imlay's conviction of equi­ ward Musquiz (Smith, manuscript in preparation). valency and of continuity of the Kiamichi from the West Nueces Formation (New Name) East Texas embayment into the Rio Grande embay­ ment. The bases for his conclusions have since been Name proposal. The West Nueces Formation is rejected by many workers, and the name McKnight here proposed as a replacement name for the so- has been revived (Winter, 1961a-c, 1962) for sub­ called "Edwards" and "Comanche Peak" plus "Wal­ nut" formations as applied in the Maverick basin surface usage west of the San Marcos platform. area of the Rio Grande embayment. The name is The unit has been securely extended to the outcrop, taken from exposures in the type area along the and the name McKnight is herewith applied to the West , eastern Kmney and western surface exposures. Uvalde counties, Texas. Provisional status of name. Although the intent Type section and type locality. The type section of Winter (1961c, p. 19) is implicit, and many of (Figure 10) is exposed in bluffs on the left bank the specific requirements of the Code (Art. 13) have of the West Nueces River, about 372 miles north- been met, Winter designated no interval (type sec­ tion) in any specified well (type locality), and the 'This is the situation in many early definitions of stratigraphic units, for example the Edwards Limestone (Lozo, 1959, p. 4). name thus lacks critical elements of definition for 298 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

MC KNIGHT

all clam wackestone to mudstone with common iliolids, pellet merits; Gryphmet* abundant in upper half and e commonly f i1le Z spar; Grynhaca grainstone with crirrt in up r 1.5 feet o

< 2

Miliolid, pellet, shell fragment gr stone with burrows along bedding surfaces. .,

WN-D-5 "90 4 WN-H-4

.^ • 3 80 Miliolid, shell fragment wackestone with common pellets and burrows; scattered * oysters and clams; common large brown pellets in basal 2 feet with snails and

u ).M. -,-k:

Z

Lumpy, burrowed, shell fragment wackestone with cor mon Fxogyra texana, Lu veral tnin, hard, browi cross-bedded, miliolid, shell fragment grainston.

LiJ oi £ o S«=L

20 £ Nodular, burrowed, shell fragment wackestone with abundant large brown pellets WN-I-2 miliolids abundant; £• texana, heart clams, Lanatia, and large oysters ed; algae scattered to locally abundant.

COVERED

GLEN 1 Bu f f, f i soft, blue dolomitic clay abo' ROSE s.ciL \/L=

EXPLANATION

* - Exogyra texana Burrowed C Heart clam Mottled 8S0 Gastropods Nodular ••"• Shell fragments, small oysters or clams -U-UTT Borings Miliolids, pellets or rounded fragments, quartz and Stylolite

fr--^--\ i i r-. .•.- -i pV.'V-- V A b&—1 ; Dole Chert Marl Mudstone Wackestone GrainstO mite or recrystallized limestone Figure 10. Graphic section of the West Nueces Formation at the type locality; bluffs on the West Nueces River. 3.5 miles north­ west of State Highway 334 road crossing, Kinney County, Texas. 7 299

SALMON PEAK

13 Thin-bedded mudstone in upper * feet, covered belo

Thin-bedded, gray, 0.06 to 0.12-mm pellet gr and recrystalliied beds and thin chert laye

Corroded and recrysta 1 lized with thin layers of ed mudstone; bedding highly contorted in pi'a

Z . of recrystalliled, anguLar, thin-bedded o

250 Laminated to "flaggy" beds of pellet and nonpellet mudstone with common thin che 9 layers and nodules

< 8 Alternating beds of shell fragment wackestone and laminated mudstone with a thin WN-DT-3 layer of black, laminated, fissile mudstone with filamentous organic material near the middle ,

ce. Dark brown, laminated, fissile mudstone with thin filaments of black organi O material and common thin-shell fragments ,

Light to dark brown, laminated to thin-bedded, slightly fissile, brittle mudstone (?); has shaly appearance and has common thin oyster shells

White mudstone wi th

* White mudstone very thinly laminated and fissile; has "shaly" appe I O ^ ^ 200 Poor recovery; mostly white mudstone with rare shell fragments, scattered pellet "V or miliolids and solutioner! zones; lower level of miliolid, shell fragment z grainstone with lithoclasts {This unit is a well developed breccia on the Laguna Road.)

190 u 5 180 Thin-bedded, brown, pellet grainstone* with shell fragment grainstone interbeds 2 in upper part and corroded and slightly brecciated layers in lower part; thin layered chert in upper and lower 1 foot

-170

Thin-bedded, brown, rippled, Gryphaea fragment grtiin s tones with several corroded 160 1 and slightly brecciated layers and thin chert layers; ripples of 1,5- to 2 ft WJ length, 3- to 5-inch wave height, bearing of crests indeterminate

:m|

WEST NUECES FORMATION B^;*., ^t£) * "c~Z *T^r*"

E X P L A N A T O N

J - *- Shell fragments, small oysters or clams --—"- Ripples ^^ Fissile Wiliotids, pellets or rounded fragments, quarti send tyfr&r Leached and altered I I 1- .• - A nrrri fcsi—^ Mudstone Wackestone Grainstone Breccia Chert or recrystallized limestone Figure 11. Graphic section of the McKnight Formation. Composite outcrop reference section: lower 37 feet from the Bitter Ranch section, Kinney County; remainder from Chalk Bluff section and core, Uvalde County. 300 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964 a> -® i. e.aw.c. 10-22 WEST NUECES RIVER GEORGE PARDI W. W. CORE HOLE a ELECTRIC LOG p COMPOSITE ELECTRIC LOG

—-""^ Figure 12. Correlation diagram of the West Nueces composite section, Kinney and Uvalde counties, and the International Bound­ ary and Water Commission ID-22 core test, Val Verde County, Texas. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 301

10 Recrystallized li

9 Inaccessible (OT descr iption; large oysters at top. Z o

<

oc - O z Mudston with abundant large chert masses ated in definite levels 0.04- m calci te mass* s common; fr

<

Mudstone without the small dark pla but wi th com all calcite in. hell fragments; hard nodul with chert ce in upper 4 fe

o

—I <

Mudstone with abundant small dark places and 0.03- to 0.05-mm calcite upper seams stylolitic

_J Same as below with scattered Macraster and Crypha

Mudstone with rare shell fragments and common globogerinids; small, dark

Mudstone with scattered thin shell fragments and abundant small spherical masses stained dark with manganese (?); stylolitic seams and Gryphaca in upper part. -WN-H-12 *300 Conglomerate; pieces up to several inches long of pellet grainstone of mixed shell fragment, lithoclast, fecal-pellet wackestone-packs MC KNIGHT

EXPLANATION

Mudstone or recrystallized limestone Conglomerate -Chert Figure 13. Graphic section of the Salmon Peak Formation (lower unit) at the type locality; Chalk Bluff on the Nueces River^ 17 miles northwest of Uvalde, Uvalde County, Texas. 302 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

z -10

°> No V) -20 o » o ^ -30 W/DCO Resistivity Log

z IBiP o \- < gSg 'ipunti; Eiotyn 5 \_J^ - ~ -• - wl \ "Tan . limey cl. -60 \ X^.

-*~L^wv- ,h -70 ( ; •o»s filled < •"W**^-^-*-^ lo.tr 0.8 fo<

^80 ^

f////////////A • GPCH•3 -90

z o -100

< -110 <- 2 -

(Kite to tan, vnf -ill sorted, porous, (tntnlly -120 liied. 0.1-0.S mm pellet grain.tone with mllii caprinid Irumtnli, c lam molds, and shell fngmi 2 cm; upper 10 leet has layers of fine to co.ru / 30 feci contains scattered chert nodules.

J •J> ••••••*•;•• -uo /

Z o 2

-160

-170

EXPLANATION

© H*ort ckoM flfifl Gastropods ~VT Burrowed -A*w St|

*-- Shell fragmMti, tmall oyjterj or clam Miliolids, peHe*s or rounded frogmevrti, quartz sand

Mud stone *bckesto*e recrystallized limestone

Figure 14. Graphic section of the Salmon Peak Formation (upper unit), from the Shell Development Co., Gliprge Pardi Corehole No. 1, 6 miles northwest of Uvalde, Uvalde County, Texas. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 303 formal establishment as a subsurface unit1. Although Maverick basin of the Rio Grande embayment. The the unit is now known to outcrop, and an outcrop formation is characteristically exposed in the vicinity type section could be defined (and another name of Salmon Peak, Turkey Mountain quadrangle, 19 proposed), informal priority and familiar usage of miles northeast of Brackettville, Kinney County McKnight would seem to favor retaining the sub­ (Bennett and Sayre, 1962, pi. 5), after which the surface name and defining a subsurface type section. unit is named. Outcrop reference section. The surface reference Type section and type locality. The type section section (Figure 11) of the McKnight is a composite of the Salmon Peak Formation is taken from two of two sections: The lower part is from a bluff localities. The lower part (Figure 13) is from the (WN-III, Figure 15) on the right bank of the West 320-foot maximum exposed section at Chalk Bluff Nueces River on the Bitter Ranch, 1.2 miles south of on the Nueces River, Uvalde County, about 14 miles the Tularosa road intersection with the "river road," southeast of Salmon Peak. The uppermost 75 feet northeastern Kinney County; the upper part is from (Figure 14), incompletely exposed in the type area, the basal 75 feet of Chalk Bluff (WN-IV, Figure 15) is described from a cored interval3 depth 86-161 on the Nueces River, 2 miles south of Nineteen Mile feet) on the George Pardi Diamond P Ranch (cf. Crossing of State Highway 55 (Uvalde-Rocksprings Chalk Bluff quadrangle), 8 miles southeast of Chalk road), western Uvalde County. On the U.S.G.S. Bluff. Turkey Mountain quadrangle, 1:62,500, the Bitter Ranch bluff (opposite the mouth of Miguel Canyon) Summary lithologic description and contacts. The is 3.5 miles due west of Salmon Peak. Chalk Bluff, type section is about 380 feet thick and in the type about 4 miles south-southeast of Laguna, is in the area of Uvalde and Kinney counties is divisible into northwest corner of the Chalk Bluff topographic two distinct parts: a lower, 305-foot unit of thick- quadrangle, 1:24,0002. bedded, white, globigerinid lime mudstone with large, irregular masses of chert in the upper half, Summary lithologic description. The maximum and an upper, 75-foot unit of worn shell fragment outcrop thickness of the McKnight is about 145 feet, grainstone cross-bedded near the top and with scat­ and the section is divisible into lower and upper tered caprinid fragments throughout (Figure 12). thin-bedded limestone units separated by a petroli­ The upper grainstone unit, a tongue of Devils River ferous 25-foot section of black, laminated, fissile, lithofacies, is replaced southward by the mudstone. clayey lime mudstone beds. The 70-foot lower sec­ At the outcrop, the Salmon Peak disconformably tion of brown shell fragment and pellet grainstones overlies the McKnight, and the basal bed is conglo­ with thin chert layers is overlain by lighter mud- meratic with pholad-bored pieces of the thin-bedded, stones with solutioned zones and collapse breccia. fecal pellet McKnight grainstone in a lime mud­ The 55-foot upper unit, as exposed at Chalk Bluff, stone matrix. The upper contact is likewise an emer­ is mostly thin-bedded mudstone; it also contains sion surface underlying the lower Del Rio (West thin chert layers, solution zones, and another col­ Prong beds of Greenwood, 1956). lapse breccia bed near the middle. The solution zones and breccia beds represent evaporite beds in Area of application. The Salmon Peak Formation the subsurface (Figure 12). is coextensive with the McKnight on both sides of the Rio Grande and is present in similar facies over Areal outcrops. In southwest Texas the total sec­ the entire Maverick basin. tion is exposed only in the reference area of north­ eastern Kinney and northwestern Uvalde counties. SUMMARY Exposures of the upper portion are present on-the West Fork of Sycamore Creek, 9 miles southeast of In the course of a regional stratigraphic synthesis Carta Valley, southwestern Edwards County, and of the Edwards Plateau Cretaceous, the impropriety on the Devils River in southern Val Verde County and ambiguity of the current outcrop nomenclature at the easternmost point of Slaughter Bend and at has been thoroughly examined. Evaluated in the the mouth of Dead Mans Creek, 11 river miles up­ light of present data, certain previously used forma­ stream. In Mexico, the McKnight encircles the south­ tion names are recommended for replacement and eastern end of the Serrania del Burro. new names are proposed accordingly; other named units are emended or supported for formal accept­ ance. The revisions are: Salmon Peak Formation (New Name) Name Proposal. The Salmon Peak Formation is West Nueces Formation to replace "Edwards" here proposed as a replacement name for the so- (new) plus "Comanche Peak" called "Georgetown Limestone" as applied in the McKnight Formation ^ , Ulr. . ,.„ (Winter, 1961) t0 rePlace *****<*» 'No decision, in conjunction with subsurface workers, has been attempted to designate the namesake well as the type well or 3The Shell Development Co., No. 1 George Pardi corehole is to specify the interval (compare Winter's depths of 6630 to 6.15 miles northwest of the State Highway 55 overpass of the 6950 with Imlay's 6615 or 6730 to 7038; it may be noted Southern Pacific railroad, 800 feet southeast of the Diamond that Mrs. Kniker's original determination of the McKnight P ranchhouse, 400 feet northeast of the highway, in Tobin was from 6875-7038). grid 6S-2E. The location scales 50 feet from the south line, 2These localities were field trip stops 7 and 9, respectively, of 2600 feet from the east line, G.C. and S.F. R.R. survey, Blk. the Gulf Coast Association of Geological Societies 1961 field 591. The core is to be deposited with The University of Texas, trip. Bureau of Economic Geology, Austin. 304 TRANSACTIONS—GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XIV, 1964

Salmon Peak Formation to replace Darton, H. N. (1933), Guidebook of the Western (new) "Georgetown" United States, Part F, The Southern Pacific Deyils River Formation Lines, New Orleans to Los Angeles, U. S. Geol. (Udden, 1907) areally restricted Surv. Bull. 845, 304 pp. In accordance with the Code of Stratigraphic No­ Dumble, E. T. (1895), Cretaceous of Western Texas menclature, definitions, sections, localities, areas of and Coahuila, Mexico, Bull. Geol. Soc. Am., v. applicability and other basic data are presented in 6, 375-388. Support of the revision submitted. A geologic map Dunham, R. J. (1962), Classification of Carbonate of the critical outcrop reference area in the southern Rocks According to Depositional Texture, in Edwards Plateau is included (Figure 15). Classification of Carbonate Rocks — A Sym­ REFERENCES posium, Memoir No. 1, pp. 108-121, 7 pis., Am, Assoc. Petr. Geol., Tulsa, Oklahoma. Adkins, W. S. (1933), The Mesozoic Systems in Texas, in The Geology of Texas, v. 1, Strati­ Edson, D. J., Jr. (1951), Comanche Series, Lancas­ graphy, Univ. Texas Rull. 3232, pp. 239-518. ter Hill, Crockett County, Texas, Unpublished , and Lozo, F. E. (1951), Stra­ M.A. Thesis, The University of Texas. tigraphy of the Woodbine and Eagle Ford, Fritts, H. M. (1933), The Surface Geology of West Waco Area, Texas, in the Woodbine and Ad­ Texas, with Special Reference to Northwestern jacent Strata of the Waco Area of Central Tex­ Crockett County, Shell Petroleum Corp., Report as — A Symposium, Fondren Sci. Ser. No. 4, Geol. Texas No. 333 (unpublished private re­ Southern Methodist Univ. Press, pp. 101-164, port) . 26 figs., 6 pis. Getzendaner, F. M. (1931), Mineral Resources of American Commission on Stratigraphic Nomencla­ Uvalde, Zavala, and Maverick Counties, Univ. ture (1961), Code of Stratigraphic Nomencla­ Texas Bur. Econ. Geol., Mineral Resource Pam­ ture, Bull. Am. Assoc. Petr. Geol., v. 45, No. 5, phlets, pp. 93-140, figs. 10-15. 645-665. Greenwood, Robert (1956), Submarine Volcanic Barnes, V. E. (1944), Gypsum in the Edwards Mudflows and Limestone Dikes in the Grayson Limestone of Central Texas, Univ. Texas Pub. Formation (Cretaceous) of Central Texas, Gulf 4301, pp. 35-46, illus. Coast Assoc. Geol. Soc, Transactions, v. 6, 167- \ (1952-1956), Geologic Maps, 177, 5 figs. Abstract: XX Cong. Geol. Internac, Scale 1;.31,680, of 7Vi — minute Quadrangles Resumenes, p. 28, 1956. in Gillespie and Adjoining Counties, Texas, Gulf Coast Association of Geological Societies (1961), Univ. Texas Bur. Econ. Geol., Geol. Quad. Maps Field Trip Guidebook — Southern Edwards 1-20. Plateau — 11th Ann. Mtg., October 28-29, 1961, Bennett, R. R. and Sayre, A. N. (1962), Geology viii + 22 pp., appendix and illus. (multilith). and Ground-Water Geology of Kinney County, Hazzard, R. T. (1956), Cretaceous Rocks South of Texas, Texas Water Comm., Bull. 6216, 163 Tarpley to Del Rio and Road Log, Part III, San pp., 15 figs., 26 pis. Angelo Geol. Soc. Field Trip March 1956 (Four Calvert, W. R. (1928), Geologic Features of Val Provinces Guidebook, March 16-17, 1956), pp. Verde County, Texas, Oil and Gas J., v. 26, 43-72. No. 36, 81-82, 85. (1959), The Age of the Yel­ Cheetham, R. N. (1949), General Geology of the lowish Marl above the Georgetown in North­ Del Rio Area, Texas, Unpublished M.S. Thesis, western Val Verde County and Southwestern State University of Iowa. Crockett County, A Discussion, West Texas Geol. Soc. 1959 Field Trip Guidebook (Geology Christaer, D. D. and Wheeler, O. C. (1918), The of the Val Verde Basin), pp. 60-63, illus. Geology of Terrell County, Univ. Texas Bull. 1819, 49 pp., illus., map. Hill, R. T. (1891), The Comanche Series of the Texas-Arkansas Region. Bull., Geol. Soc. Am. Cragin, F. W. (1894), Observations on the Geology v. 2, p. 503-528. of Adjacent Parts of Oklahoma and Northwest Texas, Acad. Nat. Sci. Philadelphia, Proc. 1894, and Vaughan, T. W. (1898a), pp. 63-68. Description of the Nueces Quadrangle, U. S. Curry, W. H., Jr. (1933), The Surface Geology of Geol. Surv. Geol. Atlas, Nueces Folio (No. 42), a Part of the Edwards Plateau Region of Texas, 4 pp., maps. Shell Petroleum Corp., Report Geol. Texas No. and Vaughan, T. W. (1898b), 334 (unpublished private report). Geology of the Edwards Plateau and Rio Grande ^ (1934), Fredericksburg-Wash­ Plain Adjacent to Austin and San Antonio, ita (Edwards-Georgetown) Contact in Edwards Texas, with Reference to the Occurrence of Plateau Region of Texas, Bull. Am. Assoc. Petr. Underground Waters, U. S. Geol. Surv. Ann. Geol., v. 18, No. 12, 1698-1705. Rpt. 18, Part 2, pp. 193-321, illus., maps. LOZO-SMITH: REVISION COMANCHE NOMENCLATURE, SOUTHWEST TEXAS 305

: (1901), Geography and Geolo­ Sandidge, J. R. (1946), Expanding Activities of Pa­ gy of the Black and Grand Prairies, Texas, U. S. leontologists, Bull. Am. Assoc. Petr. Geol., v. Geol. Surv. Ann. Rpt. 21, Part 7, 666 pp., illus., 30, No. 7, 1088-1094. maps. Sayre, A. N. (1936), Geology and Ground-Water Imlay, R. W. (1945), Subsurface Lower Cretaceous Resources of Uvalde and Medina Counties, Tex­ Formations of South Texas, Bull. Am. Assoc. as, U. S. Geol. Surv. Water-Supply Paper 678, Petr. Geol., v. 29, No. 10, 1416-1469, 5 figs. 146 pp., illus.

International Boundary and Water Commission Shumard, G. G. (1886), A Partial Report on the (1955), Geologic Strip Maps, Scale 1:50,000, Geology of Western Texas .'..., State Printing covering an area about 3 miles on each side of Office, Austin, Texas, 145 pp. the Rio Grande from Lajitas, Brewster County, to Del Rio, Val Verde County (9 maps plus index map), Intern. Bound, and Water Comm. South Texas Geological Society (1960), Guidebook (El Paso). Open-file material available at Bu­ Fall Field Trip, December 2-3, 1960, Taylor reau of Economic Geology, Austin, Texas. to Glen Rose Geological Section, iv + 25 pp., appendix, illus. (mimeo.). Liddle, R. A. and Prettyman, T. M. (1920), Geology and Mineral Resources of Crockett County with (1962), Contributions to the Notes on the Stratigraphy, Structure, and Oil Geology of South Texas, 308 pp., San Antonio, Prospects of the Central Pecos Valley, Univ. Texas. Texas Bull. 1857, 97 pp., 4 pis. Spice, J. O. (1954), Geology of the Northwest Part Long, A. T. (1958), Ground-Water Geology of Real of the Dry Devil Quadrangle, Val Verde Coun­ County, Texas, Texas Board Water Engineers, ty, Texas, Unpublished M.A. Thesis, The Uni­ Bull. 5803, 46 pp., 10 figs., 3 pis. versity of Texas.

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