Geology of the Cedar Mesa-Boundary Butte area, San Juan County, Utah

The Cedar Mesa-Boundary Butte area lies within the Colorado Plateau and includes about 650 square miles in southern San Juan County, Utah. Altitudes ranges from 3,890 feet on the westward-flowing San Juan River, the major and only perennial stream, to more than 6,400 feet on Cedar Mesa in the northwest. Bare rocks, high mesas, sheer cliffs, and deep canyons characterize the area. Comb Ridge, a prominent hogback of eastward-dipping rocks, trends north through the middle part of the area and is the most conspicuous topographic feature. The only permanent settlements are Bluff in the east and Mexican Hat in the west, both on the San Juan River.