Washington, the Evergreen State, occupies the northwest corner of the United States, with the Pacific Ocean on the west, Canada on the north, Idaho on the east, and Oregon on the south. Although its northwest corner is chewed out by the sea, and its southern border is determined by the meanderings of the Columbia River from the point where it swings westward, the State is roughly rectangular, measuring 360 miles east to west and 240 miles north to south. With a water area of 1,721 square miles and a land area of 66,836 square miles, Washington is larger than all New England.
The State, consisting of seven distinct physiographic areas -- the Olympic Mountains, Willapa Hills, Puget Sound Basin, Cascade Mountains, Okanogan Highlands, Columbia Basin, and Blue Mountains -- represents virtually every topographic variation known in the United States.
The Olympic Mountains, a part of the coastal range, lie between Puget Sound, Juan de Fuca Strait, and the Pacific Ocean, and are separated from the Willapa Hills by the valley of the Chehalis River. The region presents a labyrinth of peaks -- Mount Olympus (8,150 alt.), Mount Fitzhenry (8,098 alt.), and Mount Constance (7,717 alt.), outstanding -- and serrated ridges, broken and eroded. Alpine valleys lakes, and torrential rivers are numerous.
South of the Olympic Mountains are the Willapa Hills, a region of sedimentary and igneous rocks of the Tertiary period. Relatively low, rarely approaching 3,000 feet in elevation, this area receives less rainfall than the northern region, yet vegetation is rank, and there are many streams draining into the Columbia River and Willapa Harbor. Only along the bank of the Columbia River do the hills become abrupt.
The Puget Sound Basin lies between the Olympic and Cascade Mountains in the form of a broad trough, extending from Juan de Fuca Strait, which connects Puget Sound with the Pacific, half way to the Columbia River. It averages 100 feet in elevation in its central portion, while its flanks rise to join the mountains. Based upon rugged folds of sedimentary rocks, rock beds, glaciation, and lava flows, the erosion of innumerable streams has made it relatively uniform. At its southern end are extended plains, reaching almost to the Columbia River. Puget Sound, for which the basin is the trough, is 80 miles long, 8 miles wide at the broadest point, and has depths of 900 feet: a body of water flanked by forested bluffs and low dikelands, with extensive bays, inlets, and passages between the 300 islands that lie within its shores, Of these, the 172 inhabitable islands of the San Juan group (see Island Tour 3) and Whidbey Island, second largest in continental United States, are most noteworthy.
Extending across the State from north to south at its approximate middle longitude is the great barrier of the Cascade Mountains -- shaped somewhat like an hour-glass -- a range, 100 miles wide at the Canadian and Oregon boundaries, and 50 miles at its middle. The numerous peaks average from 6,000 to 8,000 feet in elevation, while the volcanic cones of Mounts Rainier, St. Helens, Baker, Adams, and Glacier Peak rise much higher. Of these peaks, only one, Mount Adams, is on the range axis; the others, St. Helens, Baker, Glacier Peak, and Rainier are on the western flank. Because of their origin, the northern and southern Cascades are quite dissimilar. The rugged southern portion resulted from great igneous activity due to volcanoes, while the northern portion, seemingly a great raised plateau at one time, is more uniform; whatever ruggedness it possesses has resulted from erosion rather than from volcanic action. The streams of the range, as a whole, are strong and deeply bedded. Mountain valleys, once the beds of great glaciers, have been deeply eroded -- leaving grand cirques and amphitheaters, such as the water-filled gorge of Lake Chelan, that are among the great attractions of the range. Only the Columbia River crosses the Cascade Mountains. Three tunnels -- the Cascade, the Rockdale, and the Stampedepierce the Cascades for rail transportation; and the Chinook, Stevens, and Snoqualmie passes make them surmountable by highways.
North of the "Big Bend" of the Columbia River and north of the Spokane River, and merging into the Cascades on the west and the Rockies on the east, are the Okanogan Highlands: beautifully rounded, broad, low hills sloping gently from watersheds to the river beds, with divides -- often 6,000 feet in elevation -- never sharp or abrupt. The Highlands, unlike the heavily wooded Cascades, are largely open and park-like, with a minimum of undergrowth.
South of the Okanogan Highlands almost to the Oregon boundary,and extending east of the Cascades almost to the Idaho boundary, is the Columbia Basin, an area of approximately 1,500,000 acres of sage and scabland. From an elevation of 500 feet at the Columbia River, lowest point in the region, the basin rises rapidly westward toward the foothills of the Cascades; eastward, the rise is more gradual to an elevation of approximately 2,000 feet at the Idaho Line. Ridges, extending east and west through the basin and marking the eroded course of past ice sheets, once rose across streams, but the latter in time have cut through them. The area of the Big Bend is scarred by great, ancient, long-dry river courses, of which Moses Coulee and Grand Coulee are excellent examples. Some of the coulees, however, still hold chains of lakes, strongly alkaline. From the region of the deep canyons of the Snake River and its tributaries, rolling plateaus -- the Palouse Country -- extend north and east, a fertile region of wind-borne soil deposits. In the southeastern corner of the State are the Blue Mountains, a prominent uplift of some 7,000 feet in the lava plain. The rounded domes, rising 2,000 to 4,000 feet above the surrounding basin lands, receive, in contrast to the contiguous country, enough rainfall to support forest growth. The streams, in deep valleys, have affected general contours very little.