WASHBOARD CANYON. Washboard Canyon, a valley with an intermittent stream, rises two miles southeast of the Brown Ranch headquarters in southeastern Pecos County (at 30°07' N, 102°35' W) and runs southeast twenty-nine miles to a point on the Rio Grande near the Brewster county line in southern Terrell County (at 29°53' N, 102°19' W). Candilla Canyon, Isinglass Canyon, and San Francisco Creek are tributaries. The route of the canyon sharply dissects massive limestone on flat terrain and crosses alluvial fans of sand, gravel, and mud on steep to gentle slopes. Generally dark, calcareous stony clays and clay loams support scrub brush, oaks, junipers, grasses, and mesquites. The name is descriptive; the wide floor is covered with creek rubble and is bumpy.