Ground Water Geology Of Edwards County Texas PDF Download

Excerpt from Geology and Groundwater Studies in Part of the Edwards Plateau of Texas: Including Sutton and Adjacent Counties In the vicinity of Lowrey Draw the exposed rocks consist of hard, nearly pure limestones, which predominate on the valley sides and ridges, and of softer, nodular, marly limestones, which occur on the undissected plateau and in the lower parts of the valleys. Among the purer strata are numerous rudistid reefs. All these rocks appear to belong to zone D and to be of Georgetown age, although the uppermost marly strata may be equivalent to the Grayson forma tion. The dolomitic beds of zone C have been found in wells. Although throughout most of the Edwards Plateau the strata appear nearly horizontal, all evidence confirms the structure proposed by Cartwright, in which the Cretaceous beds drape over the hills and sag into the valleys of the buried pre-cretaceous surface. As a result, in Sutton County they form a broad syncline, plunging gently toward the southwest, with highs toward the northwest and the northeast, and they also probably form a narrower syncline along the South Llano River, southeast of which they drape over the Edwards Arch. In southern and southwestern Edwards and in Val Verde County, all the strata dip more steeply southward and southwestward toward the Balcones fault zone. Except for the rudistid reefs, most of the limestones of the western Edwards Plateau have little or no primary permeability, but transmit water through their joints and solution openings. The dolomitic beds, however, are permeable and appear to be the most important aquifer. Their occurrence in numerous wells and their outcrops on all sides of the plateau indicate that they probably underlie the entire region, but their permeability varies greatly from place to place. At most places their groundwater is under a slight artesian head, probably due to water standing in the joints of the overlying limestones. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.