Cimarron National Grassland and Point of Rocks

The Cimarron National Grassland covers 108,175 acres of Morton and Stevens counties, the largest public land in Kansas, in the old territory of the Comanche and their allies and an Apache hunting ground. It is shortgrass prairie dominated by sand sagebrush, cut by the Cimarron River, which is usually dry on the surface from late summer through winter, though lush growth and groves of cottonwood line its banks, and beaver dams make pools below Middle Spring. Bluffs rise about a hundred feet above the valley, and the best known of them, Point of Rocks, was the landmark wagon drivers on the trail's Dry Route watched for after the waterless stretch, because it meant springs.

The bluff is a short lesson in the geology of southwest Kansas. Its cap is white Ogallala Formation calcrete, sand and gravel washed off the Rocky Mountains millions of years ago and cemented hard. Beneath lie red shales, siltstones and sandstones whose age geologists argued over for more than a century, guessing everything from Permian to Cretaceous. Kansas Geological Survey researchers settled it by measuring uranium and lead in tiny zircon grains: the red beds are the Permian Big Basin Formation, named for the mile-wide sinkhole in Clark County where it was first identified.

The Forest Service's 30-mile auto tour, mostly on dirt roads, passes a prairie dog town, the trail, Point of Rocks and the river. The Cimarron Recreation Area has 12 campsites under cottonwoods and the 10.5-mile Turkey Trail.