CASCADE MOUNTAINS, a continuation northward of the Sierra Nevada, about 500m. across the States of Oregon and Washington, U.S.A., into British Columbia. In U.S. territory the range lies from 1 oo to 150m. from the coast. The Cascades are separated on the south from the Sierras by deep valleys near Mt. Shasta in California, while on the north somewhat below the inter national boundary of 49° N. they approach the northern Rockies, mingling with these in inextricable confusion. The Cascades are in general a comparatively low, broad mass surmounted by a number of imposing peaks in Oregon and Washington. Evidences of volcanic activity in comparatively recent geologic time are abundant throughout the length of the range, and all the highest summits are volcanic cones, covered with snow fields and, in a number of instances, with glaciers. The grandest peaks are Shasta (14,I 6I ft.) at the south, and Rainier (or Tacoma, 14,408f t.) in Washington, two of the most magnificent mountains of America. Other notable summits are Mt. McLoughlin (9493) formerly Pitt, Mt. Scott (8,938), Diamond Peak (8,807), Mt. Thielsen (9,178), Mt. Jefferson (10,495) and Mt. Hood (11,225), in Oregon; and Stuart (9,470), St. Helens (9,671), Baker (10,750), and Adams (12,307), in Washington. The Fraser river in the far north, the Columbia at the middle, and the Klamath in the south cut athwart the range to the Pacific. The Columbia has cut al most to the sea level through the great mountain mass, the Dalles being only about iooft. above the sea. It is to the cascades of the tremendous rapids at this point that the mountains owe their name. The slopes of the Cascades are clothed with magnificent forests, chiefly of coniferous evergreens: firs, pine, tamarack, and cedar. The Douglas fir, the "Oregon pine" of commerce, often attaining a height of 25oft., is one of the most beautiful trees in the world. In 1926 the mountain forests were largely included in 13 national forest reserves, with a total area of nearly 13,500,00o acres, extending from the northern boundary of Washington to the southern boundary of Oregon.
See OREGON and WASHINGTON ; also G. O. Smith and F. C. Calkins, A Geological Reconnaissance across the Cascade Range near the Forty Ninth Parallel (1904), being U.S. Geological Survey Bulletin 253; W. D. Smith, A Summary of the Salient Features of the Geology of the Oregon Cascades, being University of Oregon Bulletin, new series, xiv., No. 16.