As the characters of the _Zauberflöte_ passed safely through the trial of fire and the desperate ordeal of water, so, through the terror of volcanic fires and the chilling empire of ice, has the great Sierra come into the present age of tranquil grandeur.
Five distinct periods divide the history of the range. First, the slow gathering of marine sediment within the early ocean during which incalculable ages were consumed. Second, in the early Jurassic period this level sea-floor came suddenly to be lifted into the air and crumpled in folds, through whose yawning fissures and ruptured axes outpoured wide zones of granite. Third, the volcanic age of fire and steam. Fourth, the glacial period, when the Sierras were one broad field of snow, with huge dragons of ice crawling down its slopes, and wearing their armor into the rocks. Fifth, the present condition, which the following chapters will describe, albeit in a desultory and inadequate manner.
From latitude 35° to latitude 39° 30´ the Sierra lifts a continuous chain, the profile culminating in several groups of peaks separated by deeply depressed curves or sharp notches, the summits varying from eight to fifteen thousand feet, seven to twelve thousand being the common range of passes. Near its southern extremity, in San Bernardino County, the range is cleft to the base with magnificent gateways opening through into the desert. From Walker’s Pass for two hundred miles northward the sky line is more uniformly elevated; the passes averaging nine thousand feet high, the actual summit a chain of peaks from thirteen to fifteen thousand feet. This serrated snow and granite outline of the Sierra Nevada, projected against the cold, clear blue, is the blade of white teeth which suggested its Spanish name.
Northward still the range gradually sinks; high peaks covered with perpetual snow are rarer and rarer. Its summit rolls on in broken, forest-covered ridges, now and then overlooked by a solitary pile of metamorphic or irruptive rock. At length, in Northern California, where it breaks down in a compressed medley of ridges, and open, level expanses of plain, the axis is maintained by a line of extinct volcanoes standing above the lowland in isolated positions. The most lofty of these, Mount Shasta, is a cone of lava fourteen thousand four hundred and forty feet high, its broad base girdled with noble forests, which give way at eight thousand feet to a cap of glaciers and snow.