_Thomas Condon Viewpoint, John Day Fossil Beds State Park._ From Picture Gorge to the cliffs opposite, the Picture Gorge Basalts and varicolored ash beds of the John Day Formation rise together nearly 2000 feet. The basalt that caps Sheep Rock is an erosional remnant. The lower beds in the John Day Formation are colored red by clay eroded from thick soil on the Clarno Formation, which is exposed in the farthest red hill. The soil was formed by tropical weathering some 30-35 million years ago, before the John Day Formation was laid down. Faulting on a small scale is illustrated in Sheep Rock, where the thick olive-drab ash flow in the middle of the John Day Formation is offset 75-100 feet (Fig. 6). The fault slopes about 45° eastward. About two miles downstream, large-scale movement on two faults has dropped the basalt flows in Middle Mountain 2000-2500 feet. One of the faults follows along the upstream base of Middle Mountain (Fig. 6). [Illustration: Fig. 5—North-south section along the John Day River through Picture Gorge and Middle Mountain.] [Illustration: Fig. 1.—Geologic map of the John Day Country showing log route.] [Higher-Resolution Map] G. 118.7 _Munro Area, John Day Fossil Beds State Park._ The valley of the John Day River has been widened to nearly five miles by erosion in the John Day Formation. Large tilted slide blocks of the John Day Formation and basalts jumbled together show how important landsliding of soft beds under hard rocks can be in widening valleys. [Illustration: Fig. 6.—Sheep Rock from Thomas Condon viewpoint.] Here one can appreciate the regularity and extent of basalt flows of the flood or plateau type, which form the Columbia Plateau. Individual flows have been traced 100 miles. Travelers will see few other rocks between here and The Dalles, Wenatchee, Pendleton, or Spokane as they cross parts of the Columbia Plateau. H. 116.2 _Cathedral Rock._ The bluff called Cathedral Rock is the front face of a large block of the John Day Formation that has slid from the west (Fig. 7). Inside the next horseshoe bend downstream a large mass of basalt is tilted down against Cathedral Rock. From the highway 1.1 miles farther north one can see the side of the tilted block along the river, and the same two prominent red and olive-drab ash layers in the high bluff from which the block slid. The horseshoe bend was formed as the river was pushed eastward by the nose of the landslide. [Illustration: Fig. 7.—View of Cathedral Rock and diagram of landsliding.] [Illustration: ] J. 107.0