BUREAU OF ECONOMIC GEOLOGY THE UNIVERSITY OF TEXAS AUSTIN 12, TEXAS

John T. Lonsdale, Director

Geologic Quadrangle Map No. 16

Harper Quadrangle, Gillespie County, Texas

By Virgil E. Barnes

July, 1954 GeologyHarperQuadrangle,GillespieCounty,oftheTexas

VirgilE.Barnes

General Setting mated to be about 90 feet thick in the Pedernales River, locality 17-23A, have Inmapping the Comanche Peak lime- in the sequence weather slowly and pebbles,cobbles, and finer materials in- lished data). A well in the Spring Hensell sand, and in the other three, part quadrangle and been identified by Ralph Imlay as stone, have only thin soil covering are cluding some Much of the ma- Creek quadrangle to east the water Harper quadrangle is in the Edwards southeastern of the Dr. points at which its boundaries a or caliche. situated the is from near the base of the consists of alternating beds of lime- follows: cross roads were placed on aerial pho- bare and nearly void of vegetation. The terial is limestone, chert, and dolomite of the center of the maximum entered Edwards limestone. Two of the springs Plateau province south of the Llano re- stone, dolomite, clay, and sand or, more tographs. In addition points of contact softer beds develop a more adequate from the Edwards limestone, and some diorite. Itis unlikely that the maximum issue from near the base, and the other gion. The plateau surface within the Tylostoma cf. regina (Cragin) correctly stated, beds having various were mapped at many places between soil and are thickly vegetated mostly is limestone from the Comanche Peak. is caused entirely by diorite, and since is located about 100 feet above the quadrangle is dissected by the Peder- Nerinea texana Roemer? proportions of these materials. Only 4 sp. portions photographs by a scrub oak identified by Cuyler All of the deposits are located in the a poorly denned superimposed maxi- base of the Edwards nales River and its tributaries in the Lunatia? roads. On of the limestone. The feet of Glen Rose beds are described Aporrhais? sp. having stereoscopic coverage the bound- (1931) as "Quercus fusiformis Sargent southeastern portion of the quadrangle. mum exists to the west of the well, it wells range from 77 to 283 feet in southern part and by Threadgill and Lunatia? pedernalis (Roemer) in the section given below. aries were traced under the stereo- (mountain scrub oak)." Alluvium— Deposits are is likely that a large diorite mass has depth, and the water level in 1936 EdwardsCreeks in the northern part. Protocardia texana (Conrad) Alluvium. of alluvium The Glen Rose limestone, consisting scope, stereoscopic coverage intruded the Packsaddle schist. stood between 19 and 232 The geology of the Harper quad- Protocardia multistriata Shumard and where The Edwards surface below the gyp- mostly situated along Pedernales River feet below of beds having varying resistance to sp. is lacking, the boundaries can still be the surface. The total solids range from rangle is shown on a planimetric map, Corbis sum horizon is mostly rocky with hard and its tributaries. A small amount in erosion, sp. parts per elsewhere in Gillespie County Protocardia very closely approximated by following The the northern part of the quadrangle is 214 to 354 million. and the only topographic map avail- Cyprimeria texana (Roemer) limestone beds and chert. chert Mineral Resources produces a terraced topography which the vegetational banding. It is possible, along and zone near able is the reconnaissance 30-minute Arctica spp. has a fairly general distribution, but Edwards Creek Maverick A the base of the Edwards shows clearly on aerial photographs. In however, the quadrangle in Kerrville quadrangle. Elevations rang- Brachydontes pedernalis (Roemer) that within some outcrop bands are free of it. Some Spring Branch. Narrow belts and The known mineral resources of the limestone is the most readily utilizable the Harper quadrangle, however, the areas covered by colluvial material, the quadrangle are limited to ing between 1,891 and 2,226 feet were Exogyra texana Roemer of the chert in the Edwards limestone patches of alluvium follow many of the nonmetallic aquifer within the quadrangle, and the slopes are more gentle, colluvial ma- Gryphaea wardiHill and Vaughan upper boundary of the Comanche Peak is of a quality suitable for the manu- lesser drainages in the area but are in- substances and water. Outside of the Hensell sand beneath should also con- determined during traversing for con- Gryphaea terials are thicker, and little of the sp. limestone has been mapped too high soil, which is mostly for range trol, only highest point was Holectypus planatus Roemer facture of artifacts, and because it was significant and have not been mapped. used tain some water. No information is but the vegetational banding so common to cf. reached. The lowest point is somewhere and that the outcrop belt of Comanche used so extensively by the aborigines, is Some of the alluvium is cultivatedand land, the most important nonmetallic available on the rocks beneath the Cre- the GlenRose is present.The Glen Rose limestone.— In Peak shown is too wide. that cleared resources are construction materials. taceous within the quadrangle, but in the southeastern part of the quad- Comanche Peak limestone the mostly referred to as flint. The Edwards some is not supports a it is limestone is not very fossiliferouswithin below, unlikely much rangle and is estimated to be at an section described the Comanche The Comanche Peak limestone is fos- limestone within the quadrangle is so growth of pecan trees. that of the the Harper quadrangle, and no elevation of about 1,800 feet, giving Peak limestone is 31 feet thick, which siliferous especially in its lower por- gently sloping and the rocks so poorly Construction Materials willbe underlain by water-bearingrocks collections were made from it. and indications exposed impossible reasonably close the surface. The about 425 feet of relief for the quad- is slightly thicker than in the adjacent tion, of are pres- that it is practically Subsurface Geology — to rangle. FredericksburgGroup quadrangles to the north and east. The ent elsewhere in it. Two collections to measure a complete section. The Building stone.stone Some limestone beds sandstones of the probably quadrangle, About two-thirds of the quadrangle Included within the Fredericksburg Comanche Peak limestone grades down- were made directly from the Comanche basal portion of the Edwardslimestone No rocks of pre-Cretaceous age crop in the Edwards limestone are of about are present beneath the but Peak limestone, and, explainedabove, along Pedernales River, however, within the quadrangle, andonly one if their depth can be judged from wells is directly drained by Pedernales River group of theHarperquadrangle is about ward into the Walnut clay. Upward it as is ex- out suitable thickness for ledge-stone to be quadrangle, and its branches. The northern third 307 feet of Edwards limestone, 30 feet grades into the Edwards limestone, and some of the fossils fromAlocality 17-23 posed in a bluff section and is de- well is known to have gone through used in building. A few of these beds to the east and west of the they will range from* about 2,500 to of the quadrangle is in the Llano River of Comanche Peak limestone, and 3 the boundary is arbitrarily placed at are also probably from the Comanche scribed below. the Cretaceous. To the east in the are of hard, light-colored limestone Peak limestone. Creek quadrangle, the Rown- 4,000 feet in depth. drainage basin and is drained by Ed- feet of Walnut clay. The boundaries the base of a thin-bedded, very fine- The fossils have been The portion of the Edwards lime- Spring which should be an attractive building by Dr. Ralph Imlay as No. Kott well entered wards Creek, Maverick Spring Branch, between the units are gradational, and grained limestone which contains chert identified fol- stone above the gypsum horizon in gen- tree 1 the stone. lows: Honeycut formation of age, — and theheadwatersof Threadgill Creek, for this quadrangle, Thompson's (1935) in some outcrops in adjacent quad- eral is composed of softer materials, RoadRoad material. Caliche derived from these, and to the southwest in the Dry Selected References which reach Llano River by way of observation that units should have rangles. Locality 17-13A, along Edwards and immediately above the gypsum the weathering of Edwards limestone Threadgill and Beaver Creek. about the rank seems logi- horizon many of the limestone are Branch quadrangle, the Owen No. 1 has been used for the surfacing of Creek of members The Comanche Peak limestone con- Creek—in north portion of quad- beds Barnes, V. E. (1944) Gypsum in the Harper quadrangle is on the introducing a rangle various angles, indicating col- Tatsch well entered rocks of Pennsyl- secondary roads and The cal. However, instead of tains considerableargillaceous material tilted at for base-course Edwards limestone of central Texas: south side of the Llano uplift, and Cre- new name, Fredericksburg could easily Monopleura pinguiseula White lapse. The Edwards limestone forming vanian age. In view of the extensive materials in highway construction. This Univ. Texas Pub. 4301, Jan. 1, 1943, especially in its basal part. The lower Caprinula crassifibra (Roemer) pre-Cretaceous pp. 35-46. taceous rocks crop out in all of the be dropped from group to formational the highest outcrops within the quad- faulting in the rocks of material while of use for surfacing portion of the Comanche Peak tends Pseudonerinea? spp. (1948) facies in quadrangle. Rocks of Cambrian and rank, especially as the U. S. Geological (Neithea) duplicicosta rangle appears to be undisturbed and the Llano uplift, many rock units may secondary roads has little value for Ouachita to be nodular, is mostly burrowed, and Pecten central Texas: Bur. Econ. Geol.,Rept. age are not far beneath the Survey excludes the Kiamichi clay from Roemer to have a very well-developed vegeta- be present. It seems likely that all units base-course material since it causes Ordovician is mostly fossiliferous. The upper por- Inv. 2, 12 pp. more deeply incised streams. The Cre- the Fredericksburg group (Wilmarth, tional banding, whereas the soft dis- of the Ordovician and possibly some freeze damage. Zones are present in the tion is much argillaceous, is well Locality A, ,Dawson, R. F., andPark- are essentially horizontal 1938, p. 776). less 17—17 about 5.6 miles east- turbed zone beneath has verylittleband- units of the Mississippian and Pennsyl- Edwards limestone, however, which taceous rocks southeast of Harper— inson, G. A. (1947) Building stones to — bedded, and is lighter colored. vanian may underlie the Cretaceous and may dip 2 or 3 feet per mile Walnut clayclay. The thickness of the Holectypus cf. engerrandi Lambert ing. The softer portion of the Edwards should make good base-course material. of central Texas: Univ. Texas Pub. the northwest. Walnut clay measuredalong Pedernales The Comanche Peak limestone is — limestone is extensively cultivated but within the quadrangle. The presence of Some of the rock in the Edwards may 4246, Dec. 8, 1942, 198 pp. discussions of the strati- River is 3 feet. It rests on and fills softer and more massive than the over- Edwards limestone.limestone The Edwards tends to have a more uniform cover of Cambrian or even pre-Cambrian rocks be hard enough for granules. Outcrops Bridge, Josiah, Barnes, V. E., and Broader Cloud, P. E., (1947) Stratig- the upper 2 of a clay bed lying Edwards limestone and tends to limestone cropping out in the Harper vegetation in the uncultivated portion beneath the Cretaceous is possible. of hard limestone in the Edwards are Jr. graphic, structural, economic, and geo- cracks in feet raphy the Upper Cambrian, Llano into steeper slopes. of physical problems of the region are in the Glen Rose. The clay of the Glen erode Within the quadrangle is about 307 feet thick, pro- than does the Edwards either above or TheC. G. Williams No. 1Oliver Hopf present about 2 miles southeast af uplift, Texas: Bull. Geol.Soc. Amer., given in references cited below. This Rose is similar to that of the Walnut Harper quadrangle, however, the Co- viding the beds between Pedernales below. well in the Martha Norrod survey is Harper along Pedernales River. A sec- vol. 58, pp. 109-124.

publication on the Harper quadrangle but does not contain Exogyra. Within manche Peak slope is much less well River and Maner triangulation station Gypsum is present about 140 feet about 600 feet south of U. S. highway tion along Pedernales River including Cloud, P. E., Jr., and Barnes, V. E. series of similar publica- the quadrangle the Walnut clay is developedthan usual, and colluvial ma- are horizontal. The lower boundary, as above the base of the Edwards lime- No. 290 and half a mile west of Flag the basal portion of the Edwards lime- (1948) The Ellenburger group of is one of a central Texas: Univ.Texas Pub. 4621, shown on shown the line. terials cover most its outcrop. Along explained above, is gradational and is stone in north-central Gillespie County; Creek. samples received stone is described below. tions, an index to which is on map as a solid color of Scattered be- June 1, 1946, 473 pp. the opposite page. The reader is re- The Walnut clay is composed of Pedernales River the massive character arbitrarily placed at the base of a thin- however, no exposure was seen in the tween depths of 405 and 615 feet are Sand and gravel.gravel— The alluvial de- Cuyler, R.H. (1931) Vegetation as an ferred to the index map to locate other highly calcareous, silty, fossiliferous of the Comanche Peak is welldisplayed beddedlimestone which in quadrangles Harper quadrangle. The gypsum bed from the Hensell sand and its basal posits along Pedernales River are thin, indicator of geologic formations: Bull. 15, quadrangles mentioned in the present clay mostly as films in impure nodular where the underlying softer Glen Rose to the east is chert bearing. The Ed- is thought to have extended over a conglomerate. 615 feet the well much silt and clay are associated with Amer. Assoc. Petr. Geol., vol. Below 67-78. outcrop beds removed, the quadrangle wide area but, as indicated by collapse pp. text. limestone. In fresh the Walnut have been thus allow- wardslimestone within is in dolomite and limestone of the the gravel, and sand is limited to Romberg,Frederick, and Barnes, V.E. is light greenish gray to light olive-gray, ing house-size blocks of the lower por- is composed of a variety of rock types structures within the quadrangle, is Honeycut formation of the Ellenburger particles of chert and limestone. The (1944) Correlation of gravity obser- tion the probably now mostly removed by solu- Geologic Formations but in most outcrops it is weathered of Comanche Peak to topple including limestone, dolomite, chert, group. Description of the samples re- deposits in generalare of littlevalue for vations with the geology of the to a yellowish gray mottled by yellow- to the river bed. and perhaps gypsum. The limestone tion. gravel. of the Edwards Smoothingiron granite mass, Llano ceived to date of publication of this sand and Some Geophysics, 9, ish orange. It is too thin to influence The Comanche Peak limestone has and dolomite vary widely in composi- No fossil collections have been made limestone, however, County, Texas: vol. Mesozoic Rocks report is given below. is suitable for the pp. 79-93. noticeably the vegetation and culture of a distinctive vegetation which on north tion, texture, thickness of beds, and from the Edwards limestone within the production The information about the pre-Cam- of crushed rock. Shield, Elgean (1937) Records of the area and in most of its outcrop is slopes in most areas shows clearly on hardness, and the expression of this Harper quadrangle, but fossils in chert wells, drillers'logs, and water analy- Cretaceous System (Lower Cretaceous) brian rocks is limited to gravity data. covered by material creeping down aerial photographs as a black band. In variation is very well shown on aerial have been seen at several places at ses in Gillespie County, Texas: State The entire quadrangle is in an area Water ShingleHills Formation from the Comanche Peak limestone and the Harperquadrangle the more thickly photographs by vegetational banding. approximately the level of the gypsum Board of Water Engineers, 51 pp. high gravity values, and highest Thompson, S. A. (1935) Fredericks- (Barnes, 1948). Edwards limestone. vegetated band, while present, not The outcrop horizon. of the A ground-water survey of Gillespie Hensell sand member is of the Edwards limestone burg group Lower Cretaceous with — value is near the eastern border of the (1937). of The Hensell sanddoes not crop out in Many fossil collectionsmade from the as distinctive as elsewhere where the has an average density of vegetation County was made by Shield special reference to north-central cover is the Rose quadrangle. Large gravity maxima in Geol., the Harper quadrangle, but it is close Walnut clay also contain fossils from colluvial less. A narrow-leaf greater than that of Glen Quarternary Deposits Most of the nine wellsand springs in- Texas: Bull. Amer. Assoc. Petr. areas of outcropping pre-Cambrian 19, the at thepoint wherePeder- the basal portion of the overlying Co- oak identified by Cuyler (1931) as limestone, and in additionis much bet- ventoried within the Harper quadrangle vol. pp. 1508-1537. to surface — (1938) of River quadrangle. manche Peaklimestone because the fos- "Quercus texana Sargent (Texas oak)" ter segregatedinto bands. TheEdwards High gravel.gravel The high gravel within rocks in the Llano uplift are associated are located in the Edwards limestone Wilmarth, M. G. Lexicon nales leaves the geologic names of the United States, — units free and is dominant tree on mostly gently sloping the quadrangle probably mostly with Packsaddle schist (Romberg and outcrop In GlenGlen Rose limestone member.member The sils from both weather the the Comanche limestone forms is area. three of the wells Part 1: U. S. Geol. Survey Bull. 896, Glen Rose limestone member is esti- intermingle. Fossils collected along Peak limestone. surfaces, and the hard limestone beds stream deposited and consists chiefly of Barnes, 1944, and subsequent unpub- water is probably produced from the 1244 pp.

Stratigraphic Section

Pedernales River Cretaceous Section Thicknessinfeet IFeet above Thicknessinfeet Feetabove Thicknessinfeet Feetabove Description Description Description Thicknessinfeet Feett above Interval Cumulative base IntervalCumulative base IntervalCumulative base Description Interval Cumulative base in part replacing fossils and in part between sive, and containing an inch-thick, dark yel- dant pelecypod and gastropod casts and in fossils. The rock is a mass of fossils, most lowish brown chert layer at base having up- lower part of intervalsomeExogyra. rredericksburg group: 80 feet measured of which are gastropods and some of which ward-extending protuberances; 46 to 48 feet Walnut clay: 3 thick Edwards limestone:— 46 feet measured - are foraminifera. one bed which is perhaps argillaceous and feet— 1. Limestone mostly extremely fine grained, 34 34 50 84 A thin section of rock from 73.5 feet is dolomitic,is recessive, and contains dark yel- 6. Limestone and clay the limestone is highly 3 80 4-7 yellowish gray, and massive but with some composed of minutely crystalline calcite con- lowish brown chert as a layer of bulbose argillaceous, nodular, yellowish gray, highly thinner bedded intervals. From 50 to 53.5 taining numerous foraminiferaand consider- nodules near base and as scattered nodules fossiliferous,and makes up most of the inter- feet highly burrowed with burrows weather- able other fossil material, mostly poorly pre- near top of interval. val. The clay is present as thin films mostly ing to form honeycombed limestone; 53.5 to served. A thin section of rock from 44 feet is lime- in thelower part of the interval. Exogyra and 55 feet massive but recessive; 55 to 57.5 feet A thin section of rock from 82 feet is lime- stone composed of minutely crystalline cal- casts of pelecypods and gastropods are abun- resistant and honeycombed from burrows; stone composed of minutely crystalline cal- cite. It contains some organic structures in- dant. Gryphaea and echinoids are common. 57.5 to 60 feet massive and recessive; 60 to cite and some fine to medium grained calcite. cluding spine-like objects. Fossils collected from this interval, locality massive, resistant, dolomitic, and in other 17-23A, are listed above. The rock in this 67 feet The rock is a mass of foraminiferaand 31 upper 4 feet honeycombed from the weather- fossil material.Many cloudy areas having the Comanche—Peak limestone: feet thick - interval has characteristics which more near- ing out of burrows:67 to 69 feet argillaceous, size of foraminifera are without structure. An 4. Limestone microgranular, highly dolomitic, 12 58 26 38 ly ally it with the Comanche Peak limestone recessive, and burrowed; 69 to 84 feet well- area containing fewer fossilsis sharplybanded trace of sand, soft, yellowish gray containing and perhaps it should have been so included. beddedlimestone ranging from medium hard and is probably a pebble. some yellowish orange specks, well bedded, ihingle Hills 4 measured and bottom and top beds massive, being formation: feet to soft. From 69.5 to 70.5 feet the limestone 2. Dolomite— microgranular, porous, yellowish 2 36 48-50 Glen Rose limestone member:4 feet described is acoquinitemostly of gastropods.Siphoneous about 3 to 4 feet thick. The middle portion — gray, resistant and containing some holes up beds from inches 7. Clay probably calcareous, light greenish 4 84 0-4 algae were collected from fallen blocks in is in ranging about 2 to 6 gray, depth to 2 inches in diameter. in and cracked to of 2 feet with river and probably came from the 2-foot bed A thin section rock from 48 feet is com- thickness. olive-gray Walnut clay filling the cracks. The feet. Siphoneous algae of between 80 and 82 posed of large areas dolomite of lime- SHIFT 75 feet down Pecan Branch to Pedernales are irregular and some are inter- there is a of and cracks were also seen at 70 feet and stone. The calcite is minutely crystalline and River anddown Pedernales River a short distance connecting and ladder or lattice-like in cross slight possibility that the block could have including :o a good exposure. The portion of the section section. The openings appear bed contains much organic material filled to be come from this horizon. The limestone some well-preserved aelow 9 feet in interval 5 is described from a cracks not mostly shell fragments, foraminifera.Some dolo- and burrows. from 80 to 84 feet is mite is present in the calcitic areas. The point 2,500 feet farther downstream. foraminifera, some siphoneous algae. This — The amount insoluble residue hydrochloric acid treatment is as follows: and dolomite is micrcgranular, contains no fossil 5. Limestone fine grained, argillaceous, in part 19 77 7 - 26 of after bed also contains some flat pebbles which remains but does contain above base Percent residue origin. rounded small dolomitic,contains some fine to very finesand Feet are intraformational in cloudy areas. section of rock from57 feet is lime- — - which decreases in amount upward, yellow- 9-17 12.9 A thin 3. very fine grained, white to yel- 10 46 38 48 ish gray, and highly fossiliferous. The bed 17-26 6.8 stone composed of minutely crystalline cal- Limestone gray, bedded, having a wide between 8 and 9 feet is in part rusty, in- 3.2 cite and some scattered fine to medium lowish well and 26-38 indistinct or- variation in thickness of beds. From 38 to durated, and cross-bedded with the cross- 38-40 9.6 grained calcite. Considerable thinly bedded; 43 mostly dipping lower ganic materialincluding foraminiferais pres- 39.5 feet very 39.5 to feet beds northwestward.In 44-50 27.0 containing dusky brown to part it is a mass of pelecypod and gastropod 5.4 ent pellet-like materialof the size massive and dark 50-55 and much large casts, and upper part it is a granular the foraminiferamay be foraminifera with yellowish brown chert as a layer of in shell 55-60 0.3 of base, another layer nodules The rest of interval is argillaceous, 60-65 the tests destroyed. nodules near of debris. 0.3

is lime- within 1foot of top, and as sporadically dis- nodular, highly burrowed, in lower part 65-70 0.6 A thin section of rock from 70 feet highly fossiliferous, composedof minutely crystalline calcjte tributed nodules in between; 43 to 46 feet and in upper part sparse- 70-75 0.2 stone thick, ly The are mostly and about 15 percent coarse grained calcite beds one-fourth inch to 3 inches reces- fossiliferous. fossils abun- 75-84 0.4

Sample Description

C.G.Williams No. 1Oliver Hopf Well Depthin Depth in Depthin feet feet feet Depthin — — — feet Dolomite very fine grained, fine grained, and microgranular; light Dolomite microgranular and yellowish gray. Abundant white chert Calcite —largecleavage fragments 775-780 gray; and downward is finer grained and less cherty. The chert is grading to pink is porcelaneous, and some very white chert is Dolomite— microgranular and white 780-790 Sand, sandstone, caliche, and clay— the sand is angular, mostly quartz, white —to light gray and porcelaneous to subchalcedonic 615-635 tripolitic— to granular. Calcite cleavage fragments are common 710-715 Dolomite microgranular, some approaching very fine grained, and and contains some microcline up to one-half inch in size. The sand- Dolomite saccharoidal, mostly microgranular and some fine grained, Dolomite mostly microgranular, and a very small amount that is very yellowish gray to white— some of it having a pinkish cast 790-795 stone is fine grained, silty, and brown. Caliche withmuch the appear- and stained as if weathered.The chert is porcelaneous,mostly white, fine grained, and yellowish gray to pinkish gray. White chert is both Dolomite and limestone mostly dolomite, as in above interval, and ance of limestone in the Ellenburger is sandy, and the clay is silty- and some— is stained pink 665-670 porcelaneous— and tripolitic to granular 715-735 some white, sublithographic ___limestone. White, porcelaneous chert is and red 405-410 Dolomite mostly very fine grained, incipiently altered, and has very Dolomite— microgranular and pinkish yellowish gray 735-745 rare — .._. 795-800 Sand and caliche— the sand is very coarse, and is composed of quartz fine pores— partly filledby a powdery material.Chert is veryscarce 670-675 Dolomite microgranular, light gray and some has a pinkish cast. The Limestone and dolomite mostly white, sublithographic limestone, some and some microcline. The caliche is similar to that from 405 to 410 Dolomite very fine grained and some fine grained, mostly light gray chert is very light gray and chalcedonic. Considerable sand has caved microgranular dolomite, and some that is very fine grained and ■ 415-420 sample from 670 from the Cretaceous light porcelaneous icct— and some is stained pink. Some porosity as in to — 745-750 medium gray. White subchalcedonic to chert is Sand very coarse and composed of quartz and microcline 420-425 675 feet.— Chert is veryabundant, white,and porcelaneous 675-680 Dolomite very fine grained, very light gray, and some has a pinkish common— _. 800-805 Sand and caliche— the sand is very coarse and is composed mostly of Dolomite very fine grained, light gray, much of it stained pink, and cast. A small amount of white chert is porcelaneous. Some Creta- Dolomite microgranular and very fine grained, and yellowish gray to quartz and some microcline. The caliche is similar to that from 405 porosity— is common between grains 680-685 ceous material— has caved 750-755 medium light gray, the latter being somewhat pyritiferous. Chips of microgranular and yellowish gray. Abundant chert is semi- Dolomite very fine grained, very light gray, and some has a pinkish limestone are rare _. to —410 feet ; 425-426 Dolomite — 805-810 Sand coarse and composedof quartz and some microcline 570-575 porcelaneous— to subchalcedonic, and yellowish gray to pinkish gray.— 685-690 cast — 755-760 Dolomite microgranular, very light gray, and a small amount of Conglomerate— fragments of chert and dolomite from Ellenburger Dolomite microgranular, yellowish gray, and some has a pinkish cast. Limestone and dolomite the limestone is sublithographic, yellowish medium gray, the latter being highly pyritiferous. Free pyrite is - - — white porcelaneous chert 690-695 gray, and the dolomite, very fine grained, very light gray, and a _ - - 810-815 pebbles ; 595-600 There is— a small amount of abundant— — small limestone ._ 815-820 Sand and conglomerate the sand is similar to that described above, Dolomite microgranular, and yellowish gray to pinkish gray. This amount— of 765-770 Dolomite— microgranular, verylight gray, and contains rare pyrite and the conglomerate is composed of weathered dolomite and chert sample contains some bright yellow mud, some —white porcelaneous Limestone sublithographic and—white. The chert is white and porce- Dolomite microgranular, very light gray, and contains a few rosettes from the Ellenburger 605-610 chert, and from705 to 710 feet, some clear calcite 695-710 laneous 770-775 of pyrite. White porcelaneous chert is common 820-825 Geologic Map of theHarper Quadrangle,Gillespie County, Texas,1954