The Pacific Northwest, Natural Features
The Coast Ranges and the Cascade Mountains dominate the terrain of the Pacific Northwest. These two north-south mountain systems run in ridges parallel to the Pacific Coast. Most of the population of the Pacific Northwest lives in the lowlands between these two mountain systems. Another major geographic feature of the Pacific Northwest is the Columbia River, one of the nation's largest rivers. It cuts through a deep gorge in the Cascade Mountains along the border between Washington and Oregon before crossing lower-elevations of the coastal mountains to empty into the Pacific.
The Cascade Mountains extend almost due north and south across central Washington, Oregon, and northern California. The mountains lie about 160 to 240 km (about 100 to 150 mi) inland from the Pacific Coast. The higher elevations of the Cascades have a continuous snow cover. A number of east-west highways built through passes provide fairly easy travel through these mountains, except in winter, when they are periodically blocked by snow.
The Cascades include a series of volcanic peaks, including Mount Rainier, which rises (4,392 m/14,410 ft), Mount Adams (3,742 m/12,276 ft), and Mount Baker (3,285 m/10,778 ft) in Washington; Mount Hood (3,426 m/11,239 ft) in Oregon; and Mount Shasta at (4,317 m/14,162 ft) in California. Some of these volcanoes are still active, including Mount Saint Helens in Washington(2,550 m/8,365 ft), which erupted violently on May 18, 1980, blowing 400 m (1,300 ft) in elevation from the peak and sending a column of ash as high as 19 km (12 mi) high. In addition, the region experiences periodic mild earthquakes.
To the west of the Cascades lies a depression containing Oregon's Willamette Valley and Washington's Puget Sound. In the south end of the depression, the winding Willamette River drains Oregon's central Willamette Valley before entering the Columbia River at Portland. The lowland depression continues north into Washington, where it submerges beneath Puget Sound, an inland extension of the Pacific Ocean lined with jagged peninsulas. The sound contains more than 300 islands, including the San Juan Islands. The Strait of Juan de Fuca provides shipping access to Puget Sound. The strait cuts west at the northern end of the sound and separates Canada's Vancouver Island from Washington's Olympic Peninsula.
To the west, the Olympic Mountains on the Olympic Peninsula are the northernmost of the U.S. Coast Ranges. Because they rise from a dense coniferous forest that lies just above sea level, the Olympics are among the most visually impressive peaks in the United States. They reach a maximum elevation of 2,428 m (7,965 ft) at Mount Olympus. The Coast Ranges continue south through the Oregon Coast Range and the Klamath Mountains before continuing down through California and the Baja California peninsula in northwestern Mexico.