Geology of Sand Rock Creek beds, Crosby County, Texas
The Sand Rock Creek beds of Crosby County, Texas, consist of light-colored dolostones, limestones, and sandstones deposited in an ancient intermittent lake basin. During major periods of lake desiccation fine grained dolostones were deposited in the central area of the basin and limestones along the periphery of the basin. Clays front outcrop sec":ions consist principally of smectite and illite with lesser amounts of sepiolite and attapulgite. Sand composition is quartz arenite. Lack of fossils, basin-wide unconformities, immature soil zones, and presence of sepiolite indicate a hostile, semi-arid paleoenvironment. Stratigraphic evidence indicates that the Sand Rock Creek beds were deposited during uppermost Pliocene and lower Pleistocene time.