BIG BRIARY CREEK. Big Briary Creek rises three miles north of Rosebud in southern Falls County (at 31°07' N, 96°58' W) and runs southeast for ten miles to its mouth on Pond Creek, twelve miles northeast of Cameron in Milam County (at 31°01' N, 96°53' W). It traverses flat to rolling prairie surfaced by dark, calcareous clays that support mesquite, cacti, and grasses.