_Strawberry Range._ This range and the Aldrich Mountains form a mountain range 50 miles long; Strawberry Mountain, altitude 9038 feet above sea level, is its highest peak. The eastern two-thirds of the Strawberry Range (Fig. 13) was raised as a great block by uplift on the John Day fault, which follows the northern base of the mountains. The rocks in Strawberry Mountain and to the east are mostly lavas which poured out over the land, whereas the Canyon Mountain part of the range consists of gabbro and peridotite which were intruded at great depth, like granite. The valleys in the higher parts of the range, above about 5000 feet, were widened from narrow V’s to their broad U profiles by glaciers during the Pleistocene Epoch, or Great Ice Age. The alluvial fans (Rattlesnake Formation) in front of the mountains were built up of bouldery gravels and finer sediments. These materials were eroded from the mountains, carried by streams down the steep narrow canyons, and spread out on the valley floor. Because much more material came into the John Day River from the Strawberry Mountains than from the lower mountains to the north, the river was pushed to the north side of its wide valley. Faulting and erosion have completely destroyed the cones of the volcanoes from which the volcanic rocks were erupted in Miocene and Pliocene time. [Illustration: Fig. 13.—Panorama of the Strawberry Range and the John Day River valley from the north.] [Illustration: Fig. 14.—Section through the Strawberry Mountain, along Strawberry Creek.] [This image in higher resolution] _Strawberry Lake and Vicinity._ At Strawberry Camp, about 12 miles south of Prairie City, the broad floor and steep walls of Strawberry Creek valley indicate that the valley has been glaciated. The precipitous cliffs and rounded valley bottom above Strawberry Lake are characteristic of glaciated mountains (Fig. 15). Strawberry Lake is dammed by landslides which probably came from the west wall of the valley after the glacier melted and left the valley wall over-steepened. The hummocky surface and blocky material in the slide are well shown along the last half mile of the trail to Strawberry Lake. Strawberry Falls mark the front of a glacial step over a massive flow of platy andesite. Little Strawberry Lake is dammed by a low glacial moraine. [Illustration: Fig. 15.—Strawberry Lake, the glaciated valley of Strawberry Creek, and cirque walls formed by the Strawberry volcanic plug.]