Mountaineering in the Sierra Nevada. Clarence King

The western margin of this continent is built of a succession of mountain chains folded in broad corrugations, like waves of stone upon whose seaward base beat the mild, small breakers of the Pacific.

By far the grandest of all these ranges is the Sierra Nevada, a long and massive uplift lying between the arid deserts of the Great Basin and the Californian exuberance of grain-field and orchard; its eastern slope, a defiant wall of rock plunging abruptly down to the plain; the western, a long, grand sweep, well watered and overgrown with cool, stately forests; its crest a line of sharp, snowy peaks springing into the sky and catching the alpenglow long after the sun has set for all the rest of America.

The Sierras have a structure and a physical character which are individual and unique. To Professor Whitney and his corps of the Geological Survey of California is due the honor of first gaining a scientific knowledge of the form, plan, and physical conditions of the Sierras. How many thousands of miles, how many toilsome climbs, we made, and what measure of patience came to be expended, cannot be told; but the general harvest is gathered in, and already a volume of great interest (the forerunner of others) has been published.

The ancient history of the Sierras goes back to a period when the Atlantic and Pacific were one ocean, in whose depths great accumulations of sand and powdered stone were gathering and being spread out in level strata.

It is not easy to assign the age in which these submarine strata were begun, nor exactly the boundaries of the embryo continents from whose shores the primeval breakers ground away sand and gravel enough to form such incredibly thick deposits.

It appears most likely that the Sierra region was submerged from the earliest Palæozoic, or perhaps even the Azoic, age. Slowly the deep ocean valley filled up, until, in the late Triassic period, the uppermost tables were in water shallow enough to drift the sands and clays into wave and ripple ridges. With what immeasurable patience, what infinite deliberation, has nature amassed the materials for these mountains! Age succeeded age; form after form of animal and plant life perished in the unfolding of the great plan of development, while the suspended sands of that primeval sea sank slowly down and were stretched in level plains upon the floor of stone.

Early in the Jurassic period an impressive and far-reaching movement of the earth’s crust took place, during which the bed of the ocean rose in crumpled waves towering high in the air and forming the mountain framework of the Western United States. This system of upheavals reached as far east as Middle Wyoming and stretched from Mexico probably into Alaska. Its numerous ridges and chains, having a general northwest trend, were crowded together in one broad zone whose western and most lofty member is the Sierra Nevada. During all of the Cretaceous period, and a part of the Tertiary, the Pacific beat upon its seaward foot-hills, tearing to pieces the rocks, crumbling and grinding the shores, and, drifting the powdered stone and pebbles beneath its waves, scattered them again in layers. This submarine table-land fringed the whole base of the range and extended westward an unknown distance under the sea. To this perpetual sea-wearing of the Sierra Nevada base was added the detritus made by the cutting out of cañons, which in great volumes continually poured into the Pacific, and was arranged upon its bottom by currents.

In the late Tertiary period a chapter of very remarkable events occurred. For a second time the evenly laid beds of the sea-bottom were crumpled by the shrinking of the earth. The ocean flowed back into deeper and narrower limits, and, fronting the Sierra Nevada, appeared the present system of Coast Ranges. The intermediate depression, or sea-trough as I like to call it, is the valley of California, and is therefore a more recent continental feature than the Sierra Nevada. At once then from the folded rocks of the Coast Ranges, from the Sierra summits and the inland plateaus, and from numberless vents caused by the fierce dynamical action, there poured out a general deluge of melted rock. From the bottom of the sea sprang up those fountains of lava whose cooled material forms many of the islands of the Pacific, and all along the coast of America, like a system of answering beacons, blazed up volcanic chimneys. The rent mountains glowed with outpourings of molten stone. Sheets of lava poured down the slopes of the Sierra, covering an immense proportion of its surface, only the high granite and metamorphic peaks reaching above the deluge. Rivers and lakes floated up in a cloud of steam and were gone forever. The misty sky of these volcanic days glowed with innumerable lurid reflections, and at intervals along the crest of the range great cones arose, blackening the sky with their plumes of mineral smoke. At length, having exhausted themselves, the volcanoes burned lower and lower, and at last by far the greater number went out altogether. With a tendency to extremes which “development” geologists would hesitate to admit, nature passed under the dominion of ice and snow.

The vast amount of ocean water which had been vaporized floated over the land, condensed upon hill-tops, chilled the lavas, and finally buried beneath an icy covering all the higher parts of the mountain system. According to well-known laws, the overburdened summits unloaded themselves by a system of glaciers. The whole Sierra crest was one pile of snow, from whose base crawled out the ice-rivers, wearing their bodies into the rock, sculpturing as they went the forms of valleys, and brightening the surface of their tracks by the friction of stones and sand which were bedded,

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