Book Cliffs  Book Cliffs, geological feature of east-central
Utah and western Colorado, U.S. Beginning near Helper, Utah, and
joined at Green River, Utah, by a second escarpment, the Roan
Cliffs, the 2,000-foot- (610-metre-) tall mountain wall, winds a
250-mile (400-km) course along the Tavaputs and Roan plateaus,
ending near Grand Junction, Colorado; it is the longest
continuous escarpment in the world. Viewed in oblique light, the
cliffs resemble a book lying on its side. Much of the rugged
region is administered as wilderness or grazing land by the
federal government.