The most important stream is the Columbia river, which forms the northern boundary for 300 m. and receives directly the waters of all the important rivers in the state except a few in the S.W. Rivers. and a few in the extreme E. About 160 m. from its mouth are the Cascades, where the river cuts through the lava beds of the Cascade Mountains and makes a descent of about 300 ft. through a canyon 6 m. long and nearly 1 m. deep. The passage of vessels through the river at this point is made possible by means of locks. Fifty-three m. farther up the stream is a second set of rapids known as the Dalles, where the stream for about 2 m. is confined within a narrow channel from 130 to 200 ft. wide The largest tributary of the Columbia is the Snake river, which for nearly 200 m. of its course forms the boundary between Oregon and Idaho. It flows through a canyon from 2000 to 5000 ft. deep, with steep walls of basaltic and kindred rocks. The powerful erosion has often caused the columnar black basalt to assume weird and fantastic shapes. The chief tributaries of the Snake river in Oregon are the Grand Ronde, Powder, Burnt, Malheur and Owyhee rivers. The principal tributaries of the Columbia E. of the Cascade Mountains and lying wholly within the state are the John Day river, which rises in the Blue Mountains and enters the Columbia 29 m. above the Dalles after pursuing a winding course of about 250 m.; and the Deschutes river, which rises on the eastern slope of the Cascade Mountains, and after flowing northward for about 320 m. enters the Columbia 12 m. above the Dalles. The Deschutes river drains a region which is less arid than the plateau farther E., and which contains a number of small lakes. A peculiar feature of the stream is the uniformity of its volume throughout the year; the great crevasses in the lava bed through which it flows form natural spillways and check any tendency of the stream to rise within its banks. The Willamette river, W. of the Cascade Mountains, is the most important stream lying wholly within the state. It rises on the western slope of the Cascades and enters the Columbia river about 100 m. above its mouth, having with its branches a length of about 300 m. In the western part of the state a number of short streams flow directly into the Pacific Ocean, the most important of these being the Rogue and the Umpqua rivers, which have their sources in the Cascades.
In Southern Oregon, especially in the Great Basin region, there are numerous lakes. Malheur Lake, in Harney county, during the wet season is about 25 m. long and has an average width of Lakes. 5 or 6 m. It is not over 10 ft. deep in any part, and is only a few inches in depth a mile from the shore. In the summer most of its bed is a playa or mud flat. Almost continuous with this body of water on the S.W. is Harney Lake, roughly circular in form and about 7-8 m. in diameter. The waters of both lakes arc alkaline, but Malheur Lake is often freshened by overflowing into Harney Lake, while the latter, having no outlet, is growing continually more alkaline. East of the Steens Mountains there is a chain of very small lakes, such as the Juniper, Manns and Alvord lakes, and also a playa known as the Alvord Desert, which in the spring is covered with a few inches, or perhaps 1 or 2 ft., of water, and becomes a lake with an area of 50 or 60 sq. m. In the summer the dry bed is smooth and very hard, and when the skies are clear the monotony of the landscape is sometimes broken by a mirage. In Lake county, occupying fault-made troughs, are several large bodies of water—Lake Abert (about 5 m. by 15 m.), Warner Lake (50 m. long, 4-8 m. wide). Summer Lake (a little smaller than Abert), and Goose Lake, the one last named lying partly in California and draining into the Sacramento system. The Upper and the Lower Klamath lakes of Klamath county are noted for their scenic beauty. Near the north-western boundary of Klamath county is the famous Crater Lake, whose surface is 6239 ft. above the sea. This lake lies in a great pit or caldera created by the wrecking in prehistoric times of the volcano Mount Mazama, which according to geologists once had an altitude of about 14,000 ft. above the sea and of 8000 ft. above the surrounding tableland; the upper portion of the mountain fell inward, possibly owing to the withdrawal of interior lava, and left a crater-like rim, or caldera, rising 2000 ft. above the surrounding country. The lake is 4 m. wide and 6 m. long, has a depth in some places of nearly 2000 ft., and is surrounded by walls of rock from 500 to 2000 ft. high. In spite of its great elevation the lake has never been known to freeze, and though it has no visible outlet its waters are fresh.
Fauna and Flora.—Large game has disappeared from the settled areas, but is still fairly abundant on the plains of the east and among the mountains of the west. In the mountain forests of south-western Oregon bears, deer, elk, pumas, wolves and foxes are plentiful. Among the south-eastern plateaus antelope are found at all seasons, and deer and big-horn (mountain sheep), and occasionally a few elk, in the winter. Bears, wolves, lynxes and foxes are also numerous in the east, and there the coyote is found in disagreeable numbers. The pocket-gopher and the jack-rabbit are so numerous as to be great pests. The principal varieties of game-birds arc ducks, geese, grouse and California quail. Sage-hens are occasionally seen on the dry plateaus and valleys, especially in Harney county. The Oregon robin (Merula naevia) and the Oregon snowbird (Junco Oregonis) arc common in Oregon and northward. On the rocky headlands and islands of the coast nest thousands of gulls, cormorants, puffins, guillemots, surf-ducks (Oedemia), dotterels, terns, petrels and numerous other birds. There, too, the Steller's sea-lion (Eumetopias stelleri) spends the mating season. The marine fauna is abundant and of great economic importance. The river fauna of the coast is of two distinct types: the type of the Columbia fauna in rivers north of the Rogue; and another type in the Klamath and its tributaries. Typical of the Columbia river is Catastomus macrocheilus and of the Klamath, C. rimiculus. Lampreys, sticklebacks, cattoids, sturgeons—the white sturgeon (Acipenser transmontanus) is commonly known as the “Oregon sturgeon”—trout and salmon are the principal anadromous fish, the salmon and trout being the most important economically. The best varieties of the salmon for canning are: the king, Chinook or quinnat (Oncorhynchus tschawytscha). far better than any other variety; and the steel-head, blue back or sukkegh (O. nerka).
The total woodland area of the state according to the United States census of 1900 was 54,300 sq. m. or 56.8 % of the land area. The Federal government established in 1907 and 1908 thirteen forest reserves in the state, ten of which had an area of more than 1,000,000 acres each; their total area on the 1st of January 1910 was 25,345 sq. m. From the coast to the eastern base of the Cascade Mountains the state is heavily timbered, except in small prairies and clearings in the Willamette and other valleys, and the most important tree is the great Douglas fir, pine or spruce (Pseudotsuga Douglasii), commonly called Oregon pine, which sometimes grows to a height of 300 ft., and which was formerly in great demand for masts and spars of sailing-vessels and for bridge timbers; the Douglas fir grows more commercial timber to the acre than any other American variety, and constitutes about five-sevenths of the total stand of the state. Timber is also found on the Blue Mountains in the north-east and on a number of mountains in the central and south-eastern parts of the state. East of the Cascades the valleys are usually treeless, save for a few willows and cottonwoods in the vicinity of streams. Over the greater part of this region the sage-brush is the most common plant, and by its ubiquity it imparts to the landscape the monotonous greyish tint so characteristic of the arid regions of the western United States. West of the Cascades most of the trees of commercial value consist of Douglas fir. Cedar and hemlock also are commercially valuable. There are small amounts of sugar pine, yellow pine, red fir and silver fir (Abies grandis and A. nobilis) and spruce; and among the broad-leaved varieties the oak, ash, maple, mahogany-birch or mountain mahogany (Cercocarpus ledifolia), aspen, cottonwood and balsam are the most common. East of the Cascades the forests consist for the most part of yellow pine. In the south-east the hills and lower slopes of the mountains are almost bare of trees. At higher altitudes, however, the moisture increases and scattered junipers begin to appear. Blending with these at their upper limit and continuing above them are clumps of mountain mahogany, which sometimes attains a height of 20 or 30 ft. Above this belt of mahogany, pines and firs are sometimes found. In this region the mountains have an upper, or cold, timber line, the height of which depends upon the severity of the climate, and a lower, or dry, timber line, which is determined by the amount of rainfall. These upper and lower limits of the timber belt are sometimes very sharply defined, so that tall mountains may be marked by a dark girdle of forest, above and below which appear walls of bare rock. In a very arid region the dry timber line may rise above the cold timber line, and in such a case the mountain will contain no forests. Of this phenomenon the Steens Mountains furnish a conspicuous example. It was estimated that the forests of Oregon contained in 1900 about 150,000,000,000 ft. of Douglas fir or spruce, 40,000,000,000 ft. of yellow pine and 35,000,000,000 ft. of other species—chiefly cedar, hemlock and spruce. In the most heavily wooded region along the Pacific coast and the lower course of the Columbia river are forests of the Douglas fir with stands of 100,000 ft. of timber per acre. The value of the lumber and timber products increased from $1,014,211 in 1870 to $6,530,757 in 1890, to $10,257,169 in 1900, and to $12,483,908 in 1905.
Climate.—Perhaps no state in the union has such great local variations in its climate as has Oregon. Along the coast the climate is humid, mild and uniform, and, as has often been remarked, very like the climate of the British Isles; in the eastern two-thirds of the state, from which the moisture-laden winds are excluded by the high coastwise mountains, the climate is dry and marked by great daily and annual ranges of temperature. The mean annual temperature varies with the elevation and the distance from the sea, being highest along the western slope of the Coast Range at altitudes below 2000 ft., and lowest in the elevated regions E. of the Cascade Mountains. The temperatures along the coast are never as high as 100° F. or as low as zero. In the valleys between the Coast Range and the Cascade Mountains the range of temperature is much greater than it is along the coast; the absolute maximum and minimum being respectively 102° and -2° at Portland, in the N.W., and 108° and -4° at Ashland, in the S.W. Owing to its greater elevation the southern portion of Oregon experiences greater extremes of temperature than the northern. In that part of the state E. of the Cascades the climate is of a continental type, with much greater ranges of temperature than in the W., although in a few low valleys, as at the Dalles, the extremes are somewhat modified. While flowers bloom throughout the year at Portland, frosts have occurred in every month of the year at Lakeview, in the Great Basin. At Astoria, near the mouth of the Columbia river, the mean annual temperature is 52° F., with extremes recorded of 97° and 10°; but at Silver Lake, in the Great