Summary Report for the 2003-2004 STATEMAP Project: Geologic Mapping to Support Improved Database Development and Understanding of Urban Corridors, Critical Aquifers and Special Areas of Environmental Concern in Texas

This Texas STATEMAP project involves geologic mapping of areas where improved geologic information can assist the management and use of land and water resources. Work during the past year focused on new geologic mapping within two project study areas (fig. 1): (1) Hill Country Trinity aquifer near Kerrville and Bandera, Central Texas, and (2) Christmas Point quadrangle-San Luis Pass area, Texas Gulf of Mexico coast. The geologic maps produced by this project will aid professionals and the public in making informed decisions regarding land use, aquifer management, and environmental protection for urban-growth corridors in Texas. Maps of the project 1 Hill Country Trinity aquifer area will be used to make decisions regarding aquifer management and modeling, land use, and environmental protection for Central Texas; a region where population growth is causing greater demands for the use of water and Earth resources. The map produced for project 2 involves a Texas Gulf of Mexico coast area near San Luis Pass, the Christmas Point quadrangle. Mapping Holocene and Pleistocene environmental geologic units associated with coastal depositional environments within this important tidal-folet area of the Texas Gulf Coast will support crucial activities such as evaluating historic changes of coastal depositional environments, addressing erosion issues, educating the public, and establishing a framework for conducting studies and presenting data for the management of other Texas inlets.

Deliverables produced for this 2003-2004 contract year are (1) project 1: 10 open-file geologic quadrangle maps (1:24,000) of the Hill Country Trinity aquifer near Kerrville and Bandera, Central Texas, and (2) project 2: open-file geologic quadrangle map (1:24,000) of the Christmas Point quadrangle-San Luis Pass area, Texas Gulf Coast. Methods used for the projects included standard field techniques, study of aerial photographs, and review of previous work. Mapping of the Christmas Point quadrangle also involved digital photography and mapping techniques.

Existing regional geologic maps that encompass project 1, Hill Country Trinity aquifer area near Kerrville and Bandera, are the 1:250,000-scale Llano sheet (Barnes, 1981) and San Antonio sheet (Brown and others, 1974). A regional map, scale 1:250,000, of Edwards Group strata was constructed by Rose (1972) during his investigation of Edwards strata. Regional maps that cover project 2, Christmas Point quadrangle-San Luis Pass area, include the 1:125,000-scale Environmental Geologic Atlas of the Texas Coastal Zone-Galveston-Houston Sheet (Fisher and others, 1972) and the 1:125,000-scale map of Submerged Lands of Texas, Galveston-Houston Area (White and others, 1985).