Olympic Mountains, highest part of the Coast Ranges, on the Olympic Peninsula, NW Wash. Mt. Olympus (7,965 ft/2,427 m) is the highest point in the mountains, which are composed mainly of sedimentary rock. The western side of the mountains is in one of the areas of greatest precipitation in the United States, with an annual rainfall of c.130 in. (330 cm); the northeast side, in the rain shadow, is in one of the driest areas on the West Coast. On the upper slopes are about 60 small glaciers fed by heavy winter snows. The greater part of the Olympic Mts. is included in Olympic National Park, 922,651 acres (373,674 hectares). Proclaimed as Mount Olympus National Monument in 1909, it was established as a national park in 1938. Rugged mountains, alpine meadows, coniferous rain forests, glaciers, lakes, and streams characterize this area. The national park includes a 50-mi (80-km) stretch of scenic Pacific shoreline that contains wildlife sanctuaries. See National Parks and Monuments (table).