Map 3363 U.S

Home , Hammett Shale

U.S. Department of the Interior Scientific Investigations Map 3363 U.S. Geological Survey Version 1.1 Pamphlet accompanies map

Kgrue

Kgrcb Kgrf Kgrcb Kgrb Kkbn Kgrcb Kgrle Kkbn Kgrb Kgrle

Kgrcb Kgrf Kgrf

Kgrb Kgrf Kgrb Kgrf Kgrf

Kgrlb

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Kgrcb Kkbn Kgrle Kgrle Site 2 Kgrb Kgrf Kgrcb

Kgrts Kgrf Kgrlb Kgrle

Kgrb Kgrb

Kgrle Kgrf

Kgrd Kgrb Kgrlb Kgrle Kgrts Kgrb Kgrle Kgrb Kgrue

Kgrb Kgrr U Kgrlb D Kgrle Kgrf Kgrlb

Kgrue

U Kgrb D Kgrf D Kgrf Kgrlb Kgrcb Kgrue U D U Kgrts U D Kgrf Kgrb Kgrts

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Kkbn Kgrlb Kgrb Kgrd Kgrf Kgrlb D Kgrts Kgrlb U Kgrd

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Kgrcb U Kgrlb Kgrd Kgrts D Kgrb Khah Kgrr Kgrr Kgrd Kgrts Kgrb Kgrb Site 1 Kcccc Kgrd Kgrd Kkbn Kkbn Kgrf Kgrts Kgrb Kgrlb Kgrlb

Kgrts U Kgrts Kgrr Kgrf Kgrf D U Kgrd D Kgrle Kgrd Kgrle Kgrb Kgrhc Kgrlb Kgrf Kgrts Kkbn Kgrb Kgrts Kgrb Kgrb Kgrcb Kgrhc Kgrlb

Kgrle Kgrts Kgrlb D Kgrlb Kgrr Kgrhc Kgrlb U Kgrr U Kgrd Kgrue U Kheh D Kgrts D

Kgrb Kgrhc Kcccc Kgrlb Kgrd Kgrle D U Kgrr

Kgrf Kgrr Kgrts U Kgrd Kgrb Kgrd Kgrb Kgrcb Kcccc D D Kgrf Kgrf

U Kgrle Kgrd Kgrlb Kheh U Kgrr D Kgrd Kgrle U

D Kgrue Kgrb Kgrd Kgrts Kgrts Kgrle Kgrhc Kgrf Kgrd Kgrf Kgrb Kgrhc Kgrb Kgrd Kgrhc Kgrlb Kgrr Kgrts Kgrb Kgrf U Kgrr Kgrts Kgrlb Kgrr D Kgrue Kgrb Kgrd Kheh Kgrlb Kgrf Kgrb Kgrts Kgrts U Kgrhc D Kgrb Kgrlb Kgrts Kheh Kgrb Kgrf Kgrle U Kgrle Kgrlb D Kgrle Kgrlb Kgrf Kkbn Kgrr Kgrlb Kgrf Kgrlb Kgrlb Kgrd Kgrd Kgrcb Kgrts Kgrf Kgrb Kgrts Kgrlb

Kgrue Kgrle Kgrd Kgrle Kgrf Kgrts Kgrr Kgrle Kgrlb Base from U.S. Geological Survey 24,000-scale Blanco, Texas (1965 edition), Kgrlb Field mapping of the hydrostratigraphic units was accomplished on an Apple iPad2 containing geospatially registered 7.5-minute USGS Payton, Texas (1963, 1987 edition), and Rough Hollow, Texas (1963, 1987 edition) 4.5° SCALE 1:24 000 Kgrb topographic maps and utilizing integrated global positioning system (GPS). North American Datum of 1983 (NAD83) 1 1/ 2 0 1 MILE The field data were transferred to Esri ArcMap (Esri, 2014), quality checked, and then used to produce the study area’s hydrostratigraphic map. TEXAS Universal Transverse Mercator Projection, zone 14 10000 1000 2000 3000 4000 5000 6000 7000 FEET Lithologic and hydrostratigraphic descriptions are from field observations and previous investigations. TRUE NORTH

MAGNETIC NORTH Digital cartography and GIS database by Diana E. Pedraza. 10.5 1 KILOMETER

APPROXIMATE MEAN LOCATION OF QUADRANGLES DECLINATION, 2016 NORTH AMERICAN VERTICAL DATUM OF 1988 Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. DESCRIPTION OF MAP UNITS ii6 Base Twin Sisters Hydrostratigraphic Unit (HSU) Table 1. Summary of the geologic framework, hydrostratigraphy, and ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas. Although this information product, for the most part, is in the public domain, ii3 Top Doeppenschmidt HSU: Rudist Reef Variant [Period, Epoch, Group, Formation, Members, and lithology modified from Whitney (1952), Lozo and Stricklin (1956), Stricklin and others (1971), Rose (1972), Stricklin and Smith (1973), Amsbury (1974), Inden (1974), Perkins (1974), Clark and others (2010), Blome and it also may contain copyrighted materials as noted in the text. Permission to Edwards Group (upper Lower Cretaceous, Albian)—Overlies the Trinity Group; mudstone, ii1 Clark (2014), Clark and others (2014), and the U.S. Geological Survey National Geologic Map Database, GEOLEX (http://ngmdb.usgs.gov/Geolex). Aquifers from Maclay and Small (1976), Ashworth (1983). Thickness from outcrop, Clark and others (2009), Weirman reproduce copyrighted items must be secured from the copyright owner. wackestone, packstone, grainstone, boundstone, dolomitic limestone, argillaceous limestone, and others (2010), and Clark and others (2014). Hydrogeologic function modified from Clark and others (2009), Weirman and others (2010), Clark and others (2014), and Clark and Morris (2015). Porosity types modified from Choquette and Pray (1970). evaporites, shale, chert. Most removed by erosion. Thickness of remaining Edwards Group 60 ft. ii1 Fabric selective: I, Interparticle porosity; SH, Shelter porosity; MO, Moldic porosity; BU, Burrowed porosity; BP, Bedding plane porosity. Not-fabric selective: FR, Fracture porosity; CH, Channel porosity; BR, Breccia; VUG, vug porosity; CV, Cave porosity. This database, identified as SIM 3363, has been approved for release and Only basal nodular member of Kainer Formation is present in study area publication by the U.S. Geological Survey (USGS). Although this database ii2 *previously published identification for the hydrostratigraphic unit; has been subjected to rigorous review and is substantially complete, the Kainer Formation (late Early Cretaceous, Albian)—Overlies the Trinity Group; mudstones, Trinity **not aerially exposed in the study area] USGS reserves the right to revise the data pursuant to further analysis and wackestone, packstone, grainstone, dolomitic limestone, shale, chert (except in the basal nodular ii1 aquifer review. Furthermore, it is released on condition that neither the USGS nor unit). Most removed by erosion. Thickness of remaining Edwards Group 60 ft. Only basal nodular Geologic framework Hydrostratigraphy ii1 the U.S. Government may be held liable for any damages resulting from its t 98°37’30” 98°30’00” 98°22’30” 98°15’30” 98°07’30” 98°00’00” member of Kainer Formation is present in study area l e

authorized or unauthorized use. B 1

l 30°15’00” a Hydrostratigraphic unit VIII—Conﬁning, locally water bearing; bedding plane, fracture r Kkbn ii1 u Thickness TEXAS t Although these data have been processed successfully on a computer c Hydrostratigraphic Hydrogeologic Porosity porosity, and minor cave porosity. Thickness 60 ft u HYEMONUMENT YEAGER HENLY DRIPPING Lithology Aquifer (feet; measured Field identification r t unit (*) function type

system at the U.S. Geological Survey (USGS), no warranty expressed or ii2 Epoch Group S at outcrop)

HILL CREEK SPRINGS PERIOD Members implied is made regarding the display or utility of the data on any other a G.Q.M. 27 Formation ii1 t Trinity Group (Lower Cretaceous)—Overlies, in the subsurface, Pennsylvanian shale (Imlay, 1940) ii2 i Approximate

BLANCO COUNTY thickness (feet) system or for general or scientific purposes, nor shall the act of distribution h Bureau of Economic Depth ii1 c Gamma Hydrostratigraphic units SPR 1:240 in the study area. Contains shale, mudstone to grainstone, boundstone, sandstone, and argillaceous ii2 KENDALL COUNTY a constitute any such warranty. The USGS or the U.S. Government shall not ii1 u Geology (Austin) O HAYS COUNTY be held liable for improper or incorrect use of the data described and/or limestone. Thickness of Trinity Group approximately 635–802 ft ii2 BANDERA COUNTY (Barnes and others, ii1 EXPLANATION 1965) Shaly, nodular limestone; burrowed mudstone and miliolid grainstone: In contained herein. COMAL Massive, nodular and mottled limestone, BRBs2 and orange wisps in ii2 40–60 western Comal County contains oyster reefs of Ceratostreon [Exogyra] VIII 40–60 Confining, locally BP, FR, Glen Rose Limestone (Lower Cretaceous, lower Aptian to middle Albian)—Alternating beds of ii1 COUNTY (Kkbn) freshly broken rock, Ceratostreon [Exogyra] texana 30°07’30” Kainer texana and caprinid biostromes which is the transition to the Walnut Clay water bearing CV

Trinity aquifer Edwards Edwards Formation

For more information concerning this publication, contact yellowish-tan, medium-bedded limestone and argillaceous limestone with minor evaporite layers. basal nodular ii1 Edwards aquifer of the Fort Terrett Director, USGS Texas Water Science Center Composed of the Lower and Upper Members, separated by a regionally extensive marker bed, Study area CRABAPPLE BLANCO PAYTON ROUGH HOLLOW DRIFTWOOD ii1 U.S. Geological Survey composed of the small fossil identified as Corbula sp. BEXAR USGS 7.5′ quadrangle boundary CREEK fossiliferous BU, BP, Argillaceous wackestone, packstone to miliolid grainstone, argillaceous Alternating beds of limestone and argillaceous limestone; fossils rare; 1505 Ferguson Lane Edwards aquifer COUNTY Camp Bullis (B) 220–230 Confining FR, occasional ii2 Balcones fault zone (most intensely faulted area) limestone; burrowed (Kgrcb) stair-step topography Austin, Texas 78754–4501 Upper Member (Lower Cretaceous, lower to middle Albian)—Massive shale, claystone, CV Sites mentioned in the text (512) 927-3500 evaporites, siltstone, mudstone, wackestone, packstone, grainstone, boundstone and argillaceous ii1 Balcones Dissolved evaporites, highly altered crystalline limestone and chalky limestone. Locally 300–390 ft thick. Composed of the following hydrostratigraphic units in Springs mentioned in the text Weathers to an orangish red pebbly texture, often has less cedar growth Or visit the Texas Water Science Center Web site at ii2 Figure 8. Photograph showing a close-up of the conglomerate/breccia bed at mudstone, breccia; commonly contains boxwork voids where the Upper evaporite (C) fault zone 0–10 Aquifer I, MO, BR and hardier, more abundant grasses, boxwork structure, springs and seeps http://tx.usgs.gov/ descending stratigraphic order: Cavernous (Kgrc), Camp Bullis (Kgrcb), upper evaporite 30°00’00” the base of the Hensell Sand at site 1 alongalong the Blanco River,River, western HaysHays evaporites have been dissolved (Kgrue) ii1 lower evaporite (Kgrue), fossiliferous (Kgrf), lower evaporite (Kgrle) County, Texas. Note circular hole where rock plug was removed. Photograph ii3 98°15'00" KENDALIA SPRING BRANCH FISCHER DEVILS WIMBERLEY BLANCO taken on July 13, 2015, by Allan Clark. Alternating wackestone, packstone, clay, and mudstone; thin, silty "platy" Kgrcb Camp Bullis hydrostratigraphic unit—Conﬁning; burrow, fracture porosity, and bedding plane. ii2 COUNTY Round BACKBONE Upper mudstone at base, Orbitolina minuta (Douglas, 1960), Porocystis MO, FR, Alternating beds of limestone and marls with Orbitolina minuta ii1 SIM 3333 Bulverde Fossiliferous (D) 120 Confining Thickness 220–230 ft Mountain golobularis, Tapes decepta, Protocardia texana, Hemiaster sp., Neithea sp., (Douglas, 1960) common ii3 Upper Trinity (Kgrf) CV near top USGS Turritella, gastropods and mollusks ii1 30°22'30" (Clark, and Morris, Kgrue 281 348–380 (typically 360) Upper evaporite hydrostratigraphic unit—Aquifer; interparticle, moldic (boxwork) and breccia Johnson Base Doeppenschmidt HSU: Rudist Reef Variant 2015) porosity. Thickness absent to 10 ft ii3 City S ii6 Y Top Rust HSU A Dripping Dissolved evaporites, highly altered crystalline limestone and chalky 290 H 29°52’30” Kgrf Fossiliferous hydrostratigraphic unit—Aquifer; interparticle, moldic, fracture and cave (near ii3 Springs Little Blanco mudstone, breccia; up to three Corbula sp. beds; lower Corbula bed up to Lower evaporite (E) Weathers to an orange; is red pebbly texture, often has less cedar growth COUNTY 8–10 Aquifer I, MO, BR ii6 290 1 foot thick with ripples common, commonly contains boxwork voids (Kgrle) and hardier grasses, boxwork structure, Corbula sp., springs and seeps top of unit). Thickness 120 ft ii5 Rough 97°52'30" Index map showing map area in yellow and adjacent U.S. Geological Survey (USGS) where evaporites have been dissolved ii6 98°37'30" Blanco Payton Hollow ii6 Quadrangle Quadrangle Quadrangle 7.5-minute quadrangles. For publications cited in this report, the agency or institution, Blanco Kgrle Lower evaporite hydrostratigraphic unit—Aquifer; interparticle, moldic (boxwork) and breccia ii4 River Blanco Site 1 Buda author, and publication year are shown. porosity. Thickness 10 ft ii3 Site 2 Salenia texana bed immediately below Corbula bed, abundant fossils Twin Twin Sisters Wackestone to grainstone, agrillaceous wackestone, shale, evaporites; BP, FR; MO and BR ii6 r Bulverde (A) 30–40 including Protocardia, pectin, Orbitolina texana (Roemer, 1852), BlanSisters ive Wimberley Salenia texana, Macraster sp., Orbitolina texana (Roemer, 1852), Confining where evaporites have ii6 COUNTY co R Porocystis, gastropods, echinoids, grades into marls, bioturbated Lower Member (Lower Cretaceous, upper Aptian)—Massive, shale, evaporites, mudstone to KENDALL (Kgrb) (typically 30) 30°00'00" G Kyle Nerinia sp., pecten, gastropods, pelecyopods been removed uad Little limestone beds, and evaporite beds grainstone, boundstone and argillaceous limestone. Locally 195–270 ft thick. Composed of the ii4 alupe iver Canyon San hydrostratigraphic units in descending stratigraphic order: Bulverde ( ), Little Blanco ( ), ii3 99°22'30" R Magic Spring Lake Kgrb Kgrlb 10 COMAL Marcos Twin Sisters (Kgrts), Doeppenschmidt (Kgrd), Rust (Kgrr) and Honey Creek (Kgrhc) ii3 COUNTY 281 Mudstone to wackestone, argillaceous wackestone, boundstone; Orbitolina MO in ii6 Honey Creek Spring 30–40 Limestone beds thicker and more resistive to erosion than overlying and 16 99°00'00" texana (Roemer, 1852), caprinid, toucasia, monopleurid, pectens, Little Blanco (B) Aquifer patch reefs, ii6 Glen Rose Limestone underlying units, Orbitolina texana (Roemer, 1852), rudist patch reefs Bulverde pelecypods, gastropods (Kgrlb) (typically 30) Kgrb Bulverde hydrostratigraphic unit—Conﬁning; moldic and breccia (where evaporites have been Me 173 46 BP, FR ii4 di na Boerne FigureFigure 5. PhotPhotographograph showingshowing an outcrooutcroppingpping of a biostrome in the

COUNTY Doeppenschmidt removed), bedding plane and fracture porosity. Thickness 30 ft ii3 BANDERA 35 ii6 Pipe Creek New Cow CreekCreek LimestoneLimestone alongalong thethe BlBlancoanco RiverRiver at sitesite 1, western Hays Braunfels CRETACEOUS Bandera Early Cretaceous Kgrlb Little Blanco hydrostratigraphic unit—Aquifer; moldic, fracture and bedding plane porosity. ii3 iver County, Texas. Photograph taken on July 13, 2015, by Robert Morris. Base Rust HSU R BEXAR 10 Thick marl beds, thin shale beds, Orbitolina texana (Roemer, 1852), ii6 COUNTY Thickness 30 ft Trinity Argillaceous wackestone and shale; Orbitolina texana (Roemer, 1852), Twin Sisters (C) 10–40 Confining often contains ponds and seeps, often little vegetation; steeper slopes I Top Honey Creek HSU 29°37'30" pelecypods, gastropods (Kgrts) (typically 30) shale beds often have "badlands" type weathering, thinner in areas of patch reefs in Kgrts Twin Sisters hydrostratigraphic unit—Conﬁning in shale beds; interparticle porosity. ii2 1604 the underlying Doeppenschmidt hydrostratigraphic unit ii1 San ii1 Balcones fault zone Thickness 10–30 ft ii2 San Antonio Lower ii1 Medina FiFiguregure 9. Corbula bed containingcontaining ripples alongalong LedgerockLedgerock Road, southeastern ii1-ii6 Lake Middle Trinity ii1 A Mudstone to grainstone, argillaceous wackestone to packstone, I, MO, Orbitolina texana (Roemer, 1852), limestone beds thicker and more ii2 n RoRoughugh HollowHollow quaquadrangle,drangle, western Hays CoCounty,unty, TeTexas.xas. NNoteote hammer for t Doeppenschmidt (D) 40–80 Kgrd Doeppenschmidt hydrostratigraphic unit—Aquifer, interparticle, moldic, burrow, fracture, o boundstone, miliolid grainstone; pectens, oysters, pelecypods, Nerinia sp., Aquifer BU, BP, resistive than overlying and underlying, patch reefs formed on rudist, n (typically 40) i

410 195–330 (typically 200–225) ( ) o scale. Photograph taken on August 18, 2015, by Robert Morris. Kgrd bedding plane, and cave porosity. Thickness 40–70 ft 10 Saint Rust Orbitolina texana (Roemer, 1852), Tylostoma sp., caprinid, toucasia, FR, CV reefal talus ii4 Hedwig monopleurid Kgrr Rust hydrostratigraphic unit—Confining; interparticle, fracture, and cave porosity. Thickness ii3 edina 40–50 ft ii6 M Alternating beds of argillaceous wackestone to packstone and mudstone to ii4 40–70 Tends to form stair-step topography with soils, Orbitolina texana R grainstone, miliolid grainstone; pectens, oysters, pelecypods, Nerinia sp., Rust (E) ii3 281 i Confining I, FR, CV v (typically 40) (Roemer, 1852) iver e Orbitolina texana (Roemer, 1852), Tylostoma sp., monopleurid (Kgrr) Kgrhc Honey Creek hydrostratigraphic unit—Aquifer; contains interparticle, moldic, burrow, 35 R r ii6 29°15'00" 37 fractured, channel, bedding plane, and cave porosity. Thickness 45–60 ft ii4 Somerset ii3 01020515MILES ii1 Honey Creek Wackestone to grainstone, boundstone, burrows, Orbitolina texana I, MO, BU, Thick beds of wackestone to grainstone; corals, caprinid, Trigonia sp., Pearsall Formation (Lower Cretaceous, upper Aptian)—Defined by Imlay (1945), contains five ii6 Honey Creek (F) 45–60 010205 15 KILOMETERS (Roemer, 1852), Trigonia sp., toucasia, caprinid, shell fragments, pectens, Aquifer BP, FR, cliff forming; outcrop often contains large limestone float with large (typically 55) members (from top to bottom): Hensell Sand, Cow Creek Limestone and Hensell Shale Members. miliolids, Turritella, and various corals (Kgrhc) CH, CV channel and moldic porosity; caves and springs ii6 Thickness 90–162 ft ii5 ii1 Base Honey Creek HSU Figure 1. Location of study area. ii4 Figure 3.3. Photograph showing contact between the Hammett Shale (bottom) Claystone, siltstone, terrigenous sand; red sandstone conglomerate/breccia Quartz geodes, large oyster shells, reddish sandy soil with good grass Hensell Sand Member (Lower Cretaceous, upper Aptian)—Sandstone and limestone. Weakly ii6 Top Hensell Sand Hensell I, MO, SH, and Cow Creek Limestone (top) along the Blanco River at site 1, western Hays 0–40 at base of unit; oysters, quartz geodes 0–40 Aquifer growth, red sandstone conglomerate/breccia at base cemented, claystone, siltstone, terrigenous sand. Quartz geodes and oysters common. Red Hensell (Kheh) CV

County, Texas. Photograph taken on July 13, 2015, by Allan Clark. Hensell Sand sandstone conglomerate/breccia at base. Thickness absent to 40 ft ii6

Kheh Very fine-grained to fine grained carbonate sand (grainstone) with I, MO, BU, Hensell hydrostratigraphic unit—Aquifer; interparticle, moldic, shelter, and cave porosity. ii1 Base Hensell Sand 26–58 localized cross-bedding; Areas of coral and rudist biostromes (boundstone) Carbonate sands, cross-bedding near top, biostrome composed of corals Cow Creek VUG, BP, Cow Creek overlain by rippled, cross-bedded grainstone 40–72 Aquifer and rudist, talus slopes Thickness absent to 40 ft ii5 Top Cow Creek Limestone EXPLANATION OF HYDROSTRATIGRAPHIC UNITS (Kcccc) FR, CH, Pearsall

Limestone CV Cow Creek Cow Creek Limestone Member (Lower Cretaceous, upper Aptian)—Lower 14 ft dolomitic 14 Dolomitic mudstone to packstone; oysters ii4 mudstone to wackestone grades to dolomitic wackestone to packstone. Oysters. Upper part very Group FormationMember Informal hydrostratigraphic unit Upper: Claystone, with siltstone lenses, overlain by fossiliferous dolomitic Confining ii3 50 limestone; Hammett 50 Confining ** Holds surface water; springs at contact with Cow Creek ﬁne-grained to ﬁne-grained carbonate sand, cross-bedded locally. Thickness about 40–72 ft. unit Kainer basal nodular of the Hammett (?) Shale Lower: siltstone and dolomite (Khah)

Edwards Kkbn VIII Hammett Contains Cow Creek hydrostratigraphic unit ii4 Formation Fort Terrett Formation

ii2 Kcccc Cow Creek hydrostratigraphic unit—Aquifer; interparticle, moldic, burrow, vug, fracture, Kgrc Cavernous (absent from study area) Figure 11. Geophysical log with breakdown of hydrostratigraphic units 1Thickness range based on minimum and maximum thickness of individual members (from field measurements and geophysical logs). The actual thickness range near the median of the possible thickness. ii2 Figure 6. Photograph showing an outcropping of strandplain at the top of the 2Black rotund bodies (BRBs) probably from oxidation of Foraminifera (Small and Maclay, 1982). bedding plane, channel and cave porosity. Thickness about 40–72 ft Figure 10. Rose diagram depicting trend of fractures. based on variations in the gamma log (30°05΄24.˝N., 98°17΄07.1˝W.). Kgrcb Camp Bullis Cow Creek Limestone at site 1 alongalong the Blanco River,River, western HaysHays County,County, Hammett Shale Member (Lower Cretaceous, upper Aptian)—Contains siltstone, thin ii2 Texas. Note dipping ripple marked beds of talus. Photograph taken on July 13, dolomite, and claystone. Lower 15 ft contains siltstone and dolomite. Upper part is claystone with ii1 Upper Kgrue Upper evaporite ii2 2015, by Robert Morris. sandstone lenses, overrun by fossiliferous, dolomitic limestone (Lozo and Stricklin, 1956; ii1 Kgrf Fossiliferous Weirman and others, 2010). Total thickness 50 ft (Lozo and Stricklin, 1956). Contains Hammett ii2 hydrostratigraphic unit ii1 Kgrle Lower evaporite Khah Hammett hydrostratigraphic unit—Conﬁning unit, little porosity. Thickness 50 ft Glen Rose ii1 Base Cow Creek Limestone Limestone Kgrb Bulverde MAP EXPLANATION Top Hammett Shale U ii1 Kgrlb Little Blanco Fault—Type unspecified, dashed where inferred. U, upthrown block; D, downthrown block Trinity D Kgrts Twin Sisters Contact—Between hydrostratigraphic units; dashed where inferred Lower Kgrd Doeppenschmidt Corbula bed contact—The Corbula sp. bed marks the boundary between the Lower and Upper Kgrr Rust Members of the Glen Rose Limestone. This report considers the Corbula marker bed to be at the Figure 2. Representation of measured section along the Blanco River at site 1, western Hays County, Texas. base of the Upper Member of the Glen Rose Limestone because three Corbula beds have been The ichnofabric index is adapted from Droser and Bottjer (1986), the carbonate scale is from Dunham (1962), Kgrhc Honey Creek found in the study area. The marker bed is the lowest of three Corbula beds. The Corbula marker and the siliciclastic scale is from Wentworth (1922). bed, which is a grainstone, averages 6 inches thick and often contains ripple marks. The overlying Hensell Sand Kheh Hensell Corbula beds are thin, often less than an inch thick, and usually contain more muds. Dashed Pearsall where inferred Formation Cow Creek Limestone Kcccc Cow Creek FigureFigure 4. PhotPhotographograph showingshowing an outcrooutcroppingpping of the Cow Creek LimestoLimestonene alongalong thethe BlBlancoanco RRiveriver at sisitete 1, western Hays County, Texas. PhPhotographotograph ttakenaken Hammett Shale Khah Hammett on July 13, 2015, by Allan Clark. Sites highlighted in the text— CONVERSION FACTORS Site 1, 30°03΄20˝N., 98°17΄14˝W., location of 195-foot measured section within the Blanco River Site 2, 30°06΄21˝N., 98°28΄39˝W., stratographic type location for the contact of the Upper and Multiply By To obtain Lower Glen Rose Limestone Length inch (in.) 2.54 centimeter (cm) Figure 7. Photograph showing a close-up of corals that form the biostrome at Study boundary inch (in.) 25.4 millimeter (mm) site 1 in the Cow Creek Limestone along the Blanco River, western Hays Figure 12. Thalassinoides network filled with grainstone dominated by Figure 13. Close-up of Thalassinoides network filled with grainstone Figure 14. Plan view of a single Planolites northwestern Blanco quadrangle, Figure 15. Rhizoliths with a yellow-tan rhizohalo observed in eastern Blanco foot (ft) 0.3048 meter (m) County, Texas. Photograph taken on July 13, 2015, by Allan Clark. mile (mi) Orbitolina texana texana with a weather-eroded weather eroded mudstone matrix, matrix western Rough Rough dodominatedminated by OrOrbitolinabitolina texana wiwithth aawea weather-erodedther-eroded mudstonemudstone matrix, matrix approxapproximatelyimately 3 mimilesleswesto west off thethetowno town off Blanco,Blanco, Texas.Texas. LensLens cap is 2.282.28 in.in. in quadranglequadrangle approapproximatelyximately 2 mmilesiles nornorthth ooff ththeetowno town off BlBlanco,anco, TeTexas,xas, aalonglong UUSS HwHwyy 1.609 kilometer (km) Hollow quadrangle, western Hays County, Texas (white box shown in detail in western Rough Hollow quadrangle, western Hays County, Texas. Photograph diameter. Photograph taken August 19, 2014, by James Golab. 281. Note head of geologic hammer for scale. Photograph taken on June 17, 2015, by figure 13). Photograph taken on July 13, 2015, by Robert Morris. taken on July 13, 2015, by Robert Morris. James Golab.

Geologic Framework, Hydrostratigraphy, and Ichnology of the Blanco, Payton, and Rough Hollow 7.5–Minute Quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas

Publishing support provided by Denver Publishing Service Center By Edit and digital layout by J.A. Herrick Manuscript approved for publication July 26, 2016 Suggested citation: Clark, A.K., Golab, J.A., and Morris, R.R., 2016, Geologic framework, hydrostratigraphy, and To learn about the USGS and its information products visit Allan K. Clark, James A. Golab, and Robert R. Morris ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall http://www.usgs.gov/ ISSN 2329-132X (online) Counties, Texas (ver. 1.1, September 20, 2016): U.S. Geological Survey Scientific Investigations Map 3363, 21 p., 1-888-ASK-USGS 2016 http://dx.doi.org/10.3133/sim3363 1 sheet, scale 1:24,000, http://dx.doi.org/10.3133/sim3363.