MORMON CREEK. Mormon (Morman) Creek rises south of Mormon Road in western Gillespie County (at 30°21' N, 99°07' W). Intermittent in its upper reaches, the stream follows a generally northerly course for ten miles to its mouth on Threadgill Creek, one-quarter mile east of Ranch Road 783 (at 30°28' N, 99°08' W). It rises in limestone hills on the eastern edge of the Edwards Plateau and crosses into part of the Llano Basin, an area characterized by flat to rolling terrain and soils ranging from shallow, stony clays and loams to deeper clayey loams. Vegetation consists primarily of brush, grasses, and open stands of live oak, Ashe juniper, and some mesquite.