Oregon

I

Introduction

Oregon, one of the Pacific states of the United States. It is bordered on the north by Washington, on the east by Idaho, on the south by Nevada and California, and on the west by the Pacific Ocean. Oregon contains some of the most beautiful scenery in the United States as well as some of the nation’s most fertile soils and richest timberlands. However, it was the beaver that first gave rise to the development of Oregon.

Oregon’s nickname, the Beaver State, harks back to the early years of the 19th century. Fur hats were fashionable at that time, in northeastern cities, and Oregon’s streams were an important source of beaver. With competition fierce among the fur companies for control of the western lands, adventurous trappers, called mountain men, became the first white people to know the region well. Later, when the rage for beaver hats had passed and Oregon’s beaver supply was all but exhausted, the mountain men showed the early pioneers a route they had picked out in their trapping years. Known as the Oregon Trail, it took thousands during the 1840s to the fertile Willamette Valley, where wheat, fruits, and vegetables thrived. Settlers were also drawn to other parts of the state, where a profitable timber industry later developed around Oregon’s bountiful supply of Douglas fir trees.

In the 1990s the timber industry, while still critical to Oregon’s economy, waned as access to old growth stands of trees diminished. Meanwhile, manufacturing grew, fueled by technology industries in the Willamette Valley.

The origin of the state name is uncertain. It may, however, be derived from the French ouragan, meaning storm or hurricane. The Columbia River may have been called the River of Storms by the early French Canadian trappers. Oregon entered the Union on February 14, 1859, as the 33rd state. Salem is Oregon’s capital. Portland is its largest city.

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II

Physical Geography

Oregon ranks tenth in size among the states, covering an area of 254,806 sq km (98,381 sq mi), including 2,719 sq km (1,050 sq mi) of inland water and 207 sq km (80 sq mi) of coastal water over which it has jurisdiction. The state has a roughly rectangular shape with a width from east to west of 669 km (416 mi) and a length from north to south of 476 km (296 mi). The mean elevation is 1,000 m (3,300 ft).

A

Natural Regions

Oregon includes parts of four major physiographic provinces (natural land regions) of the United States. The Pacific Border province occupies the western part of the state and encompasses the Oregon Coast Range, the Klamath Mountains, and the Willamette Valley. The Sierra-Cascade province is dominated by the Cascade Range, which parallels the Pacific Border province. The Columbia Plateau lies in the northeastern and north central part of the state. It is subdivided into the Blue Mountains, the Deschutes-Umatilla Plateau, the Harney Desert, and the Payette Section. In the south is Oregon’s fourth physiographic region, a subdivision of the Basin and Range province called the Great Basin.

The Oregon section of the Coast Ranges is typical of such systems, with ridges running parallel to the coast and narrow valleys between the ridges. The crests of the ridges reach an average height of 550 m (1,800 ft) in the north. In the south they are higher, reaching an average height of nearly 1,080 m (3,600 ft). The high peaks and rugged headlands along the coast are formed of igneous rock intruded into sedimentary formations. The highest of the mountains is Marys Peak (1,249 m/4,097 ft).

Abutting the Oregon Coast Range are the higher and more rugged Klamath Mountains, which extend southward into California. Their highest peaks exceed 2,100 m (7,000 ft). The ridges and peaks are made up of a complex mass of relatively old marble and limestone as well as serpentine, shale, and hard sandstone. This mountain structure has yielded considerable quantities of gold, chromite, and nickel. There are a few alluvial basins in the Klamath Mountains, notably the Rogue River Valley around the cities of Medford and Ashland, a smaller alluvial lowland near Grants Pass, and another in the vicinity of Cave Junction. These lowlands provide favorable locations for farms and cities and are densely populated.

The Willamette Valley is the only large alluvial lowland in Oregon. The heart of the state, it contains the largest cities and a majority of Oregon’s population. The Willamette River meanders back and forth across this valley, which is more than 240 km (150 mi) long and up to 50 km (30 mi) wide. Some hilly areas emerge from the lowland, such as the Salem and Eola hills in the middle of the valley. Elsewhere the lowland is level, and in places artificial drainage is required to make it habitable.

The Cascade Range, containing some of Oregon’s most magnificent scenery, extends the entire length of the state. The general level of the high plateau of the Cascades is 1,500 m (5,000 ft), but numerous sharp volcanic peaks lie above the plateau level of this mountain range. Among them is Mount Hood (3,426 m/11,239 ft), the highest peak in Oregon. Other peaks are Mount Jefferson and a series of three peaks called the Three Sisters, all of which are more than 3,000 m (10,000 ft) high. Passes traversed by east-west highways provide fairly easy travel through these mountains, except in winter, when they are sometimes blocked by snow.

The Columbia Plateau, which extends into Washington and Idaho, is primarily the result of great extrusions of lava from fissures and vents that once covered a wide area. One of the major divisions of the Columbia Plateau is formed by the Blue Mountains, which might be more accurately described as a large plateau with some steep and rugged areas. The Wallowa Mountains, which lie in the extreme northeastern part of the state, are sometimes considered a part of the Blue Mountains. In the Wallowas, erosion has exposed the granite underlying the lavas, and the highest part of this region, which is severely glaciated, contains many spectacular peaks and glacial lakes.

Good farmland is found in small alluvial basins in the northeast, around La Grande, Baker City, and Enterprise. These basins are well drained by rivers and receive water for irrigation from the adjacent mountain areas. One of the most dramatic features of this northeastern area is Hells Canyon of the Snake River, the deepest gorge in North America, running along the Oregon-Idaho border. The Snake River has cut a narrow gorge into the lava flows of the nearby mountains, forming a canyon, which in places lies 1,800 m (6,000 ft) or more below the adjacent uplands.

The Deschutes-Umatilla Plateau extends eastward from the northern Cascades to the vicinity of Pendleton. The Deschutes-Umatilla is a lava plateau dissected by the canyons of the Deschutes, John Day, Umatilla, and other rivers. The Harney Desert, or High Lava Plains, extends from the central Cascades eastward to the vicinity of Malheur Lake. It consists of relatively young lava flows, covered in places by ash and pumice. Only the irrigated part near the Cascades is very productive. The Payette Section, or Owyhee Upland, consists of old lava plateaus that have been cut up, or dissected, by the action of streams. The lower canyon of the Owyhee has been dammed to produce a long reservoir lying between rugged multicolored cliffs that irrigates a large area near the Snake River.

Oregon’s fourth physiographic region, the Great Basin, is found in south central Oregon, east of the Cascades. Here north-south ranges alternate with broad basins. Some of the basins contain intermittent lakes. An extensive irrigated area near Klamath Falls is supplied with water from the Cascade Range.

B

Rivers and Lakes

The Columbia River forms most of the Oregon-Washington boundary, and with its tributaries this great river drains a large portion of Oregon. From the point where the Columbia first touches the state, at Wallula Gap, the river runs in a shallow gorge, deepening as it approaches the Cascades. This part of the river once had many rapids and falls, but is now navigable by large vessels because of dams and locks that have been built along much of its length. An important tributary of the Columbia is the Snake River, which forms part of the Oregon-Idaho boundary. The Snake rises in Yellowstone National Park and flows through Wyoming and Idaho before reaching Oregon. It supplies water for irrigation and power. The Willamette River, the most important within the state, has its headwaters in the high Cascades, north of Crater Lake. It supplies water for cities and industries in the valley and has become an important amenity. The Deschutes River collects water from the eastern flanks of the Cascade Mountains before joining the Columbia near The Dalles. The rivers of the northern Oregon coast are short, generally draining only the western side of the Oregon Coast Range, although the Siuslaw and Umpqua rivers traverse the entire range farther south. The Rogue River drains a large area in the southwest of the state.

The lakes of Oregon include coastal dune-blocked lakes as well as the lakes of the high Cascades and several shallow basin lakes in the more arid areas. Oregon’s largest lake is Upper Klamath Lake, which lies on the eastern fringes of the Cascades. In the high Cascades, most of the lakes were formed either by glacial action or by lava flows that dammed up stream valleys. Water from these lakes is used in lower regions for irrigation and general water supply. Near the crest of the Cascades are two large lakes, Odell and Waldo. Also in the Cascades is spectacular Crater Lake, which is the deepest lake in the United States.

In the Wallowa Mountains are several lakes of glacial origin, the largest of which is Wallowa Lake. In south central Oregon, some of the lakes occupy large basins in areas of interior drainage and therefore have a sharply fluctuating water level, depending on the amount of rainfall. On occasion they even dry up. Included in this group are Summer, Abert, Harney, and Malheur lakes.

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