CHAPTER I. 



GENERAL DESCRIPTION OF THE REGIONS EXAMINED. 



General topography. — Sacramento valley. — Pit river and its tributaries — Plateau between pit river and the des chutes 

 valley. — Des chutes valley. — Cascade range in Oregon territory. —Willamette valley. — Calapooya mountains. — 

 Umpqca valley. — Umpqca mountains. — Rogue river valley. — Siskiyou mountains. — Klamath river and its tributaries. — 

 Shasta butte, and the mountain chains op northern California. 



GENERAL TOPOGRAPHY. 



There is a great similarity in the general topographical features of the whole Pacific slope. 

 The Sierra Nevada in California, and the Cascade Range in Oregon and Washington Terri- 

 tories, form a continuous wall of mountains nearly parallel to the coast, and from one to two 

 hundred miles distant from it. Where examined hy our party, the main crest of this range is 

 rarely elevated less than 6,000 feet above the level of the sea; and many of its peaks tower into 

 the region of eternal snow, the lower limit of which is about 8,000 feet above the same level. 

 This long chain of mountains forms a great natural boundary. To the eastward lies a plateau 

 of which the average altitude is about 4,500 feet above the sea. The winds from the ocean 

 deposit most of their moisture upon the western slope of the mountains, and reach the plateau 

 dry. This, together with the volcanic character of the country, renders nearly the whole region 

 an arid waste, unfit to support a civilized population. 



West of the Sierra Nevada and Cascade Ranges, the character of the country is widely different. 

 The Coast Range, another and parallel chain of mountains, but of a lesser altitude and of- a 

 more broken nature, borders the sea-shore. Between the two lie several large fertile valleys, 

 elevated but slightly above the sea, and containing nearly all the arable land of the far west ; 

 of these valleys, the San Joaquin and Tulare, the Sacramento, the Willamette, the Umpqua, 

 the Rogue river, and the Cowlitz are the chief ; but the Gulf of California itself may be con- 

 sidered one of the great series, probably produced by a common cause, and differing from the 

 rest only in being submerged. 



In northern California and southern Oregon, the two great parallel chains of mountains 

 approach each other ; and several ranges, the chief of 'which are called the Siskiyou, the Ump- 

 qua, and the Calapooya mountains, connect them, thus separating the Sacramento and Willa- 

 mette valleys by a line of transverse ridges. These ridges present the only serious obstacle to 

 the construction of a railroad from the Sacramento valley to the Columbia river. Two routes 

 between these termini were examined by our party. The first crossed the western chain of the 

 Sierra Nevada at the head of the Sacramento valley, and, after passing over the comparatively 

 level plateau of the interior until the transverse ridges had been turned, re-crossed the moun- 

 tains near the source of the Willamette river, and followed the valley of that stream to the 

 Columbia. The second lay over the transverse ridges. A general description of the region 

 traversed by each of the routes will occupy the remainder of the chapter. 

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