Devils River, an intermittent stream, rises in southwestern Sutton County at the gathering of six watercourses, Dry Devils River, Granger Draw, House Draw, Jackson Draw, Flat Rock Draw, and Rough Canyon (at 30°20' N, 100°57' W) and runs southwest for ninety-four miles to its mouth on the northeastern shore of Amistad Reservoir in southern Val Verde County (at 29°28' N, 101°04' W). On its long route thirty-two tributaries disembogue into it, including Dolan Creek, where Dolan Falls is formed, Dark Canyon, Dead Mans Creek, and Satan Canyon. The path of Devils River sharply dissects massive limestone and traverses wash deposits of sand, gravel, and mud on flat terrain. The area's generally dark, calcareous, stony clays and clay loams support oak, juniper, grasses, mesquite, and water-tolerant hardwoods and conifers. In 1590 Gaspar Castaño de Sosa, a Spanish explorer, traveled along the river and called it Laxas, meaning "slack" or "feeble." Later travelers and settlers called the river San Pedro. In the 1840s Texas Ranger captain John Coffee (Jack) Hays asked the name of the river as he stood before one of its deep canyons. Upon hearing its name, he reportedly replied that it looked more like the Devil's river than Saint Peter's. The stream was well known to early travelers because it allowed access from north to south through rugged canyonland, and it offered water. East-west expeditions followed its banks as far as possible before striking out into the desert.