Ouachita Mountains, Oklahoma as seen from STS-58

STS058-91-058 (18 Oct-1 Nov 1993) --- In this unusually clear view, the Ouachita Mountains of southeastern Oklahoma are framed on the north by Lake Eufaula on the South Canadian River, and on the south by the Red River. Sandstone, shale and chert (similar to flint) deposited in a sea several thousand feet deep were squeezed up to form the mountains about 250 million years ago. During the ensuing time, erosion of the western end of the Ouachita Mountains has emphasized linear ridges of resistant rock in the plunging anticlines and synclines, causing relief of 800 meters (2,600 feet) or more. Clouds formed by upslope winds border both the north and south sides of one of the most dramatic plunging synclines (in a syncline the rock layers dip toward the center of the structure). Toward the west, densely forested mountains give way to gently rolling, less rocky terrain and a drier climate which is better suited to farming. The mountains centered on Broken Bow, in the lower right corner of the scene, display abundant timber clearcuts that are being regenerated.