EVANS CREEK. Evans Creek, also known as Sells Creek, rises two miles southwest of Rattlesnake Gap and State Highway 163 in south central Val Verde County (at 29°46' N, 101°10' W) and runs southeast for twenty-four miles to its mouth on the north shore of Amistad Reservoir, a half mile east of the Southern Pacific line on the Mexican border (at 29°32' N, 101°04' W). The stream's course sharply dissects massive limestone as it crosses flat to rolling prairies; it ends on alluvial deposits of gravel, sand, clay, silt, and organic materials. The creek has formed a deep limestone canyon and several large caves. Soils in the area are generally dark, calcareous stony clays and clay loams that support oaks, junipers, mesquites, and grasses.