Curving through northwestern Nebraska and into the southwest corner of South Dakota, the Pine Ridge Escarpment, rising to 5000 feet, divides the watersheds of the White River, to its north, and the Niobrara River, to its south. Like the Gangplank, west of Cheyenne, and the Palmer Divide, between Denver and Colorado Springs, this ridge is an erosional remnant, molded from Tertiary sediments during the cool, wet climate of the Pleistocene.
Capped with Miocene sandstone of the Arikaree Group, the north-facing, 100 mile long escarpment represents the edge of the High Plains, which stretch away to the south. North of the ridge, the terrain drops into the Missouri Plateau, where the White River and its tributaries have produced badlands in the older sediments of the Oligocene (the White River Group). West of Pine Ridge, the Hat Creek Breaks represent similar geologic strata, rising between the watersheds of the Cheyenne and Upper Niobrara Rivers.
Named for the groves of ponderosa pine that cloak its summit and northern flank, Pine Ridge also harbors a mix of junipers and drought-tolerant shrubs (snowberry, skunkbush, chokecherry, sumac), which attract bighorn sheep, elk, mule deer, porcupines and wild turkey; predators include coyotes, bobcats and mountain lions. Naturalists can most easily explore this ridge at Ft. Robinson State Park, west of Crawford, and Chadron State Park, south of Chadron; more adventurous visitors might set their sights on the Soldier Creek Wilderness Area, WNW of Ft. Robinson. The Toadstool Geologic Park, NNW of Crawford, offers a spectacular array of Oligocene formations, exposed within the Oglala National Grassland.
