The Bristol Mountains Wilderness contains the tilted and bisected old volcanic plain called Old Dad Mountains and the northern portion of the Bristol Mountains. The broad Budweiser Wash drains into the eastern portion of the wilderness. The vegetation type is predominantly creosote bush desert scrub and desert wash scrub. Wildlife is typical for the Mojave Desert; including coyote, black-tailed jackrabbits, ground squirrels, kangaroo rats, quail, roadrunners, rattlesnakes, and several species of lizards. The Bristol Mountains also provide habitat for migrating desert bighorn sheep.