This digital geologic map compilation presents new polygon (map unit
contacts) and line (faults) vector data for the Seco Creek area in south-central
Texas. The map database, which is at 1:50,000-scale resolution, provides
geologic coverage for an area located in Medina County about 25 km northwest
of San Antonio. The map area is underlain by sedimentary rocks of Cretaceous
and Quaternary age that are offset by a series of normal faults. The stratigraphy
ranges from the Lower Cretaceous Glen Rose Limestone (oldest) to Quaternary
(youngest) alluvium. Edwards Group rock units are represented by the Devils
River and Fort Terrett Formations, the latter being equivalent to the lower
part of the Devils River Formation. The impetus for compiling the geology
of the four 7.5 degree-quadrangle (Comanche Waterhole, Flatrock Crossing,
Sabinal NE, and Texas Mountain) area was to provide a digital geologic
map database for a helicopter electromagnetic (HEM) survey flown in 2002
and for ongoing 3-D EarthVision modeling of the Edwards/Trinity aquifer
boundary. |
