. Annual report of the United States Geological Survey to the Secretary of the Interior . ateau, the Lampasas Plain, and theCallahan Divide. The Lampasas Cut Plain is the modified north-ern extension of the great Edwards Plateau,previously described. It is a greatly dissecteddip plain, now recognizable by the general levelof its many remnantal summits, which dominateall the country south of the Brazos between theWestern Cross Timbers and the Balcones faultzone. These summits, which are called moun-tains by the inhabitants, are numerous remnantalcircular Hat-topped buttes crowning the dividesbe
. Annual report of the United States Geological Survey to the Secretary of the Interior . ateau, the Lampasas Plain, and theCallahan Divide. The Lampasas Cut Plain is the modified north-ern extension of the great Edwards Plateau,previously described. It is a greatly dissecteddip plain, now recognizable by the general levelof its many remnantal summits, which dominateall the country south of the Brazos between theWestern Cross Timbers and the Balcones faultzone. These summits, which are called moun-tains by the inhabitants, are numerous remnantalcircular Hat-topped buttes crowning the dividesbetween the drainage valleys. Life and industryare mostly found in the valleys scored below thesummit levels. In general, these fragments have flat table topsand are bordered by glaring white cliffs above,lead-ing down to gentler slopes below (see PI. XIII).The tops consist of weathered surfaces of theEdwards limestone, sometimes bare of soil and inother places covered with rich but shallow blackor chocolate residual soil supporting grasses andtimber growth. Where barren the surfaces of. UNIVtHS US HILL.] REMNANTS OF THE CUT PLAIN. 79 the massive limestone weather into many minutely .sculptured ridgesand depressions, produced by the solvent effect of the rainfall uponthe hot limestones. Such forms are geologically known as In places thick superficial coatings of residual flints occur,resembling beds of waterworn gravel. These have been left behindas the limestone, which originally contained them, was slowly carriedaway by superficial or underground solution. Some of these flints,through processes of decay, develop a peculiar scoriaceous texture,the cavities of which are filled with drusy quartz which sparkles inthe sunshine. The interior border of the Edwards Cut Plain forms the generalwestern escarpment of the Grand Prairie region south of the the east the plain is less dissected and«ends abruptly at the Balconesfault zone, which is a low escarpment ha
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