Abilene Sheet Explanation

Abilene Sheet Explanation - TO ACCOMPANY MAP ABILENE SHEET...

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TH E UNIVERSITY OF TEXAS AT AUSTIN BUREAU OF ECONOMIC GEOLOGY T O ACCOMPAN Y MA P ABILEN E SHEE T GEOLOGIC ATLA S OF TEXAS GEOLOGIC ATLAS OF TEXAS, ABILENE SHEET FREDERICK BYRON PLUMMER MEMORIAL EDITION VIRGIL E. BARNES, Project Director 1972
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EXPLANATIO N Alluvium Flood-plain deposits, includes low terrace deposits near flood-plain level and bedrock locally in stream channels; thickness up to 25 feet Surficial deposits undivided Sand, clay, caliche, and gravel; includes older terrace remnants, lag gravel, residual soil, and colluvium commonly cemented by caliche; mapped where sufficiently thick and extensive to obscure bedrock, upper surface commonly slopes toward present streams, rests principally on mudstones of Clear Fork Group; contemporaneous with Qt and Qal; thickness up to 10 feet Fluviatile terrace deposits Gravel, sand, and silt. Mostly undivided, Qt. ALONG CLEAR FORK OF BRAZOS RIVER, HUBBARD CREEK, AND ELM CREEK divided into two terrace groups, low terrace deposits undivided, Qt 1, and high terrace deposits probably representing one terrace, Qt 2. Gravel, sandy, pebbles rounded, include quartz, igneous rock, and metamorphic rock from distant sources intermingled with local bedrock fragments especially along smaller streams; sand, fine- to coarse-grained quartz, reddish brown to gray; silt, sandy, clayey, bedded to lenticular, commonly cross-bedded. Thickness up to 25 feet Seymour Formation Sand, gravel, and clay, deposits separately mapped include thin deposits, Qs 1, thick deposits, Qs 2, and deposits of limestone gravel, Qs 3 Thin deposits, Qs 1, sand, friable, conglomerate in basal part, pebbles consist of chert, quartz, sandstone, limestone, and/or igneous and metamorphic rocks, cross-bedding and small channel fill deposits scarce, too thin to support much timber; thickness 1-10 feet Thick deposits, Qs 2, sand, friable, local clay lenses, bedded, basal conglomerate similar to Qs 1 may be present, thick enough to support dense growth of post oak, RESTRICTED TO NORTH SIDE OF CLEAR FORK OF BRAZOS RIVER, probably represents ancient channel deposits of the Clear Fork; thickness 10-80 feet Limestone gravel, Qs 3, mostly pebbles from Cretaceous outcrops to south and southwest, angular to moderately well rounded, calcite cement, near base some pebbles similar to those in Qs 1, deposits elongate in direction of slope, wedge-shaped in cross section, deposited by northward-flowing, high-gradient streams; thickness 5-40 feet
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Edwards Limestone, Comanche Peak Limestone, and Walnut Formation Limestone and clay stone; Edwards Limestone, Ked, SEPARATELY MAPPED IN EASTERN CAL- LAHAN COUNTY; Edwards Limestone, Comanche Peak Limestone, and Walnut Forma- tion, Kecw, UNDIVIDED IN WESTERN CALLAHAN, TAYLOR, AND RUNNELS COUNTIES; Co- manche Peak Limestone and Walnut Formation, Kcw, UNDIVIDED IN EASTERN CALLA- HAN AND NORTHERN BROWN COUNTIES; Walnut Formation, Kwa, MAPPED SEPARATELY IN ERATH COUNTY Edwards Limestone; limestone, ls, SEPARATELY MAPPED IN WESTERN PART OF AREA.
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Abilene Sheet Explanation - TO ACCOMPANY MAP ABILENE SHEET...

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