Oregon Geography: Rainforest, Volcanoes, and High Desert

Oregon's geography is among the most varied of any US state — within 300 miles you traverse temperate rainforest, major river valley, volcanic mountain range, and high desert plateau.

Coast Range and Oregon Coast
The Coast Range (highest point: Mary's Peak, 4,097 ft) runs parallel to the Pacific, draped in Sitka spruce and western hemlock forest nourished by 80–150 inches of annual precipitation in the wettest areas. The Oregon Coast — 363 miles of public beach — is defined by sea stacks, headlands, dune fields (Oregon Dunes are the largest temperate coastal dunes in North America), and fishing towns.

Willamette Valley
Between the Coast Range and the Cascades — Oregon's flat agricultural heartland, drained by the Willamette River flowing north to the Columbia. The valley has Oregon's richest soils (Jory soil, the state soil) and hosts Portland, Salem, Eugene, and most of Oregon's population. The valley's grass seed production supplies most of the US lawn and sports turf market.

Cascade Range
A chain of Quaternary volcanoes running north-south through Oregon. The major volcanic peaks: Mount Hood (11,239 ft — the highest point in Oregon and the most-climbed glaciated peak in North America after Mount Rainier), Mount Jefferson (10,495 ft), the Three Sisters (South Sister 10,358 ft is the highest), Broken Top, Newberry Volcano, Crater Lake (a caldera formed when Mount Mazama collapsed 7,700 years ago), and Mount McLoughlin. The Cascades create a sharp precipitation barrier — western Oregon is wet; eastern Oregon is arid.

Columbia Plateau
Eastern Oregon's dominant landform — a vast basalt plateau formed by the Columbia River Basalt Group (one of the largest lava flood events in Earth's recent history, 10–16 million years ago). The John Day Fossil Beds preserve an extraordinary record of Oregon's subtropical past (25–50 million years old). The Painted Hills are the most photogenic expression of the John Day Formation.

Basin and Range (Southeast Oregon)
Oregon's least-visited region — Harney County (the largest county in Oregon and one of the largest in the US) is a vast high desert of playas, rimrock, and sagebrush. Steens Mountain (9,733 ft) rises 5,000 feet from the Alvord Desert playa — one of the sharpest escarpments in the lower 48. Malheur National Wildlife Refuge is one of the most important bird migration staging areas in the western US.