ISINGLASS CANYON. Isinglass Canyon, a valley with an intermittent stream, begins four miles southwest of the Southern Pacific Railroad tracks in southwestern Terrell County at the junction of Whitely and Hagler canyons (at 30°04' N, 102°25' W) and runs southeast fifteen miles to a point (at 29°55' N, 102°22' W) on Washboard Canyon, a half mile east of the Brewster county line. Putnam Canyon meets Isinglass Canyon 2½ miles northeast of the Elders Ranch headquarters. The path of the canyon dissects massive limestone and crosses wash deposits on flat plains. Generally dark, calcareous stony clays and clay loams support oaks, junipers, grasses, and mesquites.