Guidebook of the Western United States: Part D. The Shasta Route and Coast Line

Diller, J.S.; Al, Et

From Alaska to Lower California the western coast of North America is bordered by a belt of mountains which is from 100 to 200 miles wide. This belt as a whole has been named the Pacific System. It separates the Pacific Ocean on the west from an interior plateau region, which also stretches from Alaska to Mexico. This plateau is of varied character but, as is well illustrated by the State of Nevada, much of it is arid and is seamed with mountain ranges. Attention need be directed here only to that part of the Pacific System which lies chiefly in the States of Washington, Oregon, and California, a section 1,300 miles in length. (See Pl. I.) Within these three States the Pacific System embraces a number of distinct mountain ranges from which project some of the loftiest peaks on the continent. It includes also broad valleys that are in part close to sea level. Consequently it is a region of strong contrasts in altitude and of wide diversity of scenery and climate. Before the snow disappears each summer from the crest of the Sierra Nevada the burning sun in the interior valley of California has yellowed the grain and has tinted the fruit in orchard and vineyard. Throughout the year the snow cap of Mount Rainier is in full sight from the fertile valleys of Washington, where winter severity is unknown. For its entire extent, from Alaska to Lower California, the Pacific System may in general be divided lengthwise into three parts—two long lines of mountain ranges and an intervening belt of valleys that may be called the Pacific valley belt. The northernmost member of this belt that need be considered here is the valley of Puget Sound. A low divide separates the sound from Cowlitz Valley, the next member of the belt to the south. Cowlitz Valley drains southward to the Columbia and is succeeded on the south by Willamette (wil-lam'et) Valley, whose waters flow northward into the Columbia. Willamette Valley extends southward for about 120 miles, or about halfway across the State of Oregon. Between its head and the north end of the Great Valley of California, the next member of the Pacific valley belt, there is a tract of generally mountainous country, where, for 200 miles, the threefold longitudinal division of the Pacific System into two ranges and an intervening belt of valleys is less evident than it is elsewhere. South of this interrupting mass of mountains, which is dominated by Mount Shasta, the Great Valley of California stretches for more than 400 miles, having a width in general of 40 to 50 miles. Its northern part, known as the Sacramento Valley, drains southward, and its southern part, known as the San Joaquin Valley, drains northward, Sacramento and San Joaquin rivers both flowing into San Francisco Bay. The south end of the San Joaquin Valley is separated by the transverse Tehachapi Mountains from the Mohave Desert. This in turn is separated by the San Bernardino range from the Salton Basin, which is nothing more than the former upper part of the Gulf of California, the sea having been excluded by the great mass of sediment dumped into the gulf by Colorado River. By some the Mohave Desert and the Gulf of California are regarded as parts of the Pacific valley belt. By others, however, notwithstanding the general alignment of these features with the Great Valley of California, they are regarded as parts of the plateau region that lies east of the Pacific System of mountains.