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large part destroyed by a shock that caused great damage elsewhere in the state.

North of 40° N. lat. the Coast Range and Sierra systems unite, forming a country extremely rough. The eastern half of this area is covered chiefly with volcanic plains, very dry and barren, lying between precipitous, although not very lofty, ranges; the western half is magnificently timbered, and toward the coast excessively wet. Between 35° and 36° N. lat. the Sierra at its southern end turns westward toward the coast as the Tehachapi Range. The valley is thus closed to the north and south, and is surrounded by a mountain wall, which is broken down in but a single place, the gap behind the Golden Gate at San Francisco. Through this passes the entire drainage of the interior. The length of the valley is about 450 m., its breadth averages about 40 m. if the lower foothills be included, so that the entire area is about 18,000 sq. m. The drainage basin measured from the water-partings of the enclosing mountains is some three times as great. From the mouth of the Sacramento to Redding, at the northern head of the valley, the rise is 552 ft. in 192 m., and from the mouth of the San Joaquin southward to Kern lake it is 282 ft. in 260 m.

Two great rivers drain this central basin,—the San Joaquin, whose valley comprises more than three-fifths of the entire basin, and the Sacramento, whose valley comprises the remainder. The San Joaquin is a very crooked stream flowing through a low mud-plain, with tule banks; the Sacramento is much less meandering, and its immediate basin, which is of sandy loam, is higher and more attractive than that of the San Joaquin. The eastward flanks of the Coast Range are very scantily forested, and they furnish not a single stream permanent enough to reach either the Sacramento or San Joaquin throughout the dry season. On the eastern side of both rivers are various important tributaries, fed by the more abundant rains and melting snows of the western flank of the Sierra; but these streams also shrink greatly in the dry season. The Feather, emptying into the Sacramento river about 20 m. N. of the city of Sacramento, is the most important tributary of the Sacramento river. A striking feature of the Sacramento system is that for 200 m. north of the Feather it does not receive a single tributary of any importance, though walled in by high mountains. Another peculiar and very general feature of the drainage system of the state is the presence of numerous so-called river “sinks,” where the waters disappear, either directly by evaporation or (as in Death Valley) after flowing for a time beneath the surface. These “sinks” are therefore not the true sinks of limestone regions. The popular name is applied to Owen’s lake, at the end of Owen’s river; to Mono lake, into which flow various streams rising in the Sierra between Mount Dana and Castle Peak; and to Death Valley, which contains the “sink” of the Amargosa river, and evidently was once an extensive lake, although now only a mud-flat in ordinary winters, and a dry, alkaline, desert plain in summer. All these lakes, and the other mountain lakes before referred to, show by the terraces about them that the water stood during the glacial period much higher than it does now. Tulare lake, which with Buena Vista lake and Kern lake receives the drainage of the southern Sierra, shows extreme local variations of shore-line, and is generally believed to have shrunk extremely since 1850, though of this no adequate proof yet exists. In 1900 it was about 200 sq. m. in area. In wet seasons it overflows its banks and becomes greatly extended in area, discharging its surplus waters into the San Joaquin; but in dry seasons the evaporation is so great that there is no such discharge. The drainage of Lassen, Siskiyou and Modoc counties has no outlet to the sea and is collected in a number of great alkaline lakes.

Finally along the sea below Pt. Conception are fertile coastal plains of considerable extent, separated from the interior deserts by various mountain ranges from 5000 to 7000 ft. high, and with peaks much higher (San Bernardino, 11,600; San Jacinto, 10,800; San Antonio, 10,140). Unlike the northern Sierra, the ranges of Southern California are broken down in a number of places. It is over these passes—Soledad, 2822 ft., Cajon, San Gorgonio, 2560 ft.—that the railways cross to the coast. That part of California which lies to the south and east of the southern inosculation of the Coast Range and the Sierra comprises an area of fully 50,000 sq. m., and belongs to the Basin Range region. For the most part it is excessively dry and barren. The Mohave desert—embracing Kern, Los Angeles and San Bernardino, as also a large part of San Diego, Imperial and Riverside counties—belong to the “Great Basin,” while a narrow strip along the Colorado river is in the “Open Basin Region.” They have no drainage to the sea, save fitfully for slight areas through the Colorado river. The Mohave desert is about 2000 ft. above the sea in general altitude. The southern part of the Great Basin region is vaguely designated the Colorado desert. In San Diego, Imperial and Riverside counties a number of creeks or so-called rivers, with beds that are normally dry, flow centrally toward the desert of Salton Sink or “Sea”; this is the lowest part of a large area that is depressed below the level of the sea,—at Salton 263 ft., and 287 ft. at the lowest point. In 1900 the Colorado river (q.v.) was tapped south of the Mexican boundary for water wherewith to irrigate land in the Imperial Valley along the Southern Pacific railway, adjoining Salton Sea. The river enlarged the canal, and finding a steeper gradient than that to its mouth, was diverted into the Colorado desert, flooding Salton Sea;[1] and when the break in this river was closed for the second time in February 1907, though much of its water still escaped through minor channels and by seepage, a lake more than 400 sq. m. in area was left. A permanent 60 ft. masonry dam was completed in July 1907. The region to the east of the Sierra, likewise in the Great Basin province, between the crest of that range and the Nevada boundary, is very mountainous. Owen’s river runs through it from north to south for some 180 m. Near Owen’s lake the scenery is extremely grand. The valley here is very narrow, and on either side the mountains rise from 7000 to 10,000 ft. above the lake and river. The Inyo range, on the east, is quite bare of timber, and its summits are only occasionally whitened with snow for a few days during the winter, as almost all precipitation is cut off by the higher ranges to the westward. Still further to the east some 40 m. from the lake is Death Valley (including Lost or Mesquite Valley)—the name a reminder of the fate of a party of “forty-niners” who perished here, by thirst or by starvation and exposure. Death Valley, some 50 m. long and on an average 20–25 m. broad from the crests of the inclosing mountain ranges (or 5–10 m. at their base), constitutes an independent drainage basin. It is below sea level (about 276 ft. according to recent surveys), and altogether is one of the most remarkable physical features of California. The mountains about it are high and bare and brilliant with varied colours. The Amargosa river, entering the valley from Nevada, disappears in the salty basin. Enormous quantities of borax, already exploited, and of nitrate of soda, are known to be present in the surrounding country, the former as almost pure borate of lime in Tertiary lake sediments.

The physiography of the state is the evident determinant of its climate, fauna and flora. California has the highest land and the lowest land of the United States, the greatest variety of temperature and rainfall, and of products of the soil.

Climate.—The climate is very different from that of the Atlantic coast; and indeed very different from that of any part of the country save that bordering California. Amid great variations of local weather there are some peculiar features that obtain all over the state. In the first place, the climate of the entire Pacific Coast is milder and more uniform in temperature than that of the states in corresponding latitude east of the mountains. Thus we have to go north as far as Sitka in 57° N. lat. to find the same mean yearly temperature as that of Halifax, Nova Scotia, in latitude 44° 39′. And going south along the coast, we find the mean temperature of San Diego 6° or 7° less than that of Vicksburg, Miss., or Charleston, S.C. The quantity of total annual heat supply at Puget Sound exceeds that at Philadelphia, Pittsburg, Cleveland or Omaha, all more than

  1. In December 1904 Salton Sea was dry; in February 1906 it was occupied by a lake 60 m. long.