Largest of Nevada's Wildernesses, Arc Dome comprises the southern one-third of the Toiyabe Range, a rugged spine of mountains with difficult access, and includes the range's highest summits. Arc Dome itself, at 11,775 feet, dominates the area. Much of the Wilderness lies above 10,000 feet. On the west side, the ground rises rather gradually from the Reese River Valley. On the east, steep inclines are broken by many rocky canyons. Vegetation consists of sagebrush and grass lower down, and changes to pinyon-juniper higher up, with occasional stands of pine and aspen. Desert bighorn sheep, once abundant in the state, now are seldom found except in the Jett Canyon-Twin Rivers region in the eastern section. Other wildlife species known to be established here include mountain lions, bobcats, deer, beavers, grouse and raptors. Anglers are attracted to the trout in Reese River, South Twin Creek and North Twin Creek.