California (source: Encyclopedia Britannica 1911 Edition)
The eastern slope is very precipitous, due to a great fault which drops the rocks of the Great Basin region abruptly downward several thousand feet. Rare passes cross the chain, opening at the foot of the mountains on the east and the west high on their flanks, 7000-10,000 ft. above the sea. Between 36° 20' and 38°the lowest gap of any kind is above 9000 ft., and the average height of those actually used is probably not less than rr,000 ft. The Kearsarge, most used of all, is still higher. Very few in the entire Sierra are passable by vehicles. Some forty peaks are catalogued between 5000 and 8000 ft., and there are eleven above 14,000. The highest portion of the system is between the parallels of 36° 30' and 37° 30'; here the passes are about 12,000 ft. in elevation, and the peaks range from 13,000 ft. upward,. Mount Whitney, 14,502 ft., being the highest summit of the United States, excluding Alaska. From this peak north-ward there is a gradual decline, until at the point where the Central Pacific crosses in lat. 39° 20' the elevation is only 7000 ft. Of the mountain scenery the granite pinnacles and domes of the highest Sierra opposite Owen's Lake, where there is a drop eastward into the valley of about 10,000 ft. in to m.; the snowy volcanic cone of Mt Shasta, rising ro,000 ft. above the adjacent plains; and the lovely valleys of the Coast Range, and the south fork of the King river—all these have their charms; but most beautiful of all is the unique scenery of the Yosemite Valley (q.v.).. Much of the ruggedness and beauty of the mountains is due to the erosive action of many alpine glaciers that once existed on the higher summits, and which have left behind their evidences in valleys and amphitheatres with towering walls, polished rock-expanses, glacial lakes and meadows and tumbling waterfalls. Remnants of these glaciers are still to be seen,—as notably on Mt. Shasta,—though shrunk to small dimensions. Glacial action may be studied well as far south as 36°. The canyons are largely the work of rivers, modified by glaciers that ran through them after the rivers had formed them. All of the Sierra lakes and ponds are of glacial origin and there are some thousands of them. The lower lake line is about 8000 ft.; it is lower to the north than to the south, owing to the different climate, and the different period of glacial retrogression. Of these lakes some are fresh, and some—as those of the north-east counties—alkali. The finest of all is Tahoe, 6225 ft. above the sea, lying between the true Sierras and the Basin Ranges, with peaks on several sides rising 4000-5000 ft. above it. It is 1500 ft. deep and its waters are of extraordinary purity (containing only three grains of solid matter to the gallon). Clear Lake, in the Coast Range, is another beautiful sheet of water. It is estimated by John Muir that on an average "perhaps more than a mile " of degradation took place in the last glacial period; but with regard to the whole subject of glacial action in California as in other fields, there is considerable difference of opinion. The same authority counted 65 small residual glaciers between 36° 3o' and 39°; two-thirds of them lie between 370 and 38°, on some of the highest peaks in the district of the San Joaquin, Merced, Tuolumne and Owen's rivers. They do not descend, on an average, below 11,000 ft.; the largest of all, on Mt. Shasta, descends to 9500 ft. above the sea. Volcanic action has likewise left abundant traces, especially in the northern half of the range, whereas the evidences of glacial action are most perfect (though not most abundant) in the south. Lava covers most of the northern half of the range, and there are many craters and ash-cones, some recent and of perfect form. Of these the most remarkable is Mt. Shasta. In Owen's Valley is a fine group of extinct or dormant volcanoes. Among the other indications of great geological disturbances on the Pacific Coast may also be mentioned the earthquakes to which California like the rest of the coast is liable. From 185o to 1887 almost 800 were catalogued by Professor E. H. Holden for California, Oregon and Washington. They occur in all seasons, scores of slight tremors being recorded every year by the Weather Bureau; but they are of no importance, and even of these the number affecting any particular locality is small. From 1769 to 1887 there were 10 " destructive " and 24 other " extremely severe " shocks according to the Rossi Forel nomenclatural scale of intensity. In 1812 great destruction was wrought by an earthquake that affected all the southern part of the state; in 1865 the region about San Francisco was violently disturbed; in 1872 the whole Sierra and the state of Nevada were violently shaken; and in 1906 San Francisco (q.v.) was in large part destroyed by a shock that caused great damage else-where in the state. North of 400 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 350 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 26o 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.