When the pioneers came in sight of the Sierra Nevada (snowy range), they little dreamed of the canons hidden among these mountains. Gold, and not scenery, was the object of their search. The great canons were outside of the gold regions, and so inaccessibly situated that no one except the Indians looked upon them until 1851. In that year a party of soldiers following the trail of some thieving Indians discovered and entered the Yosemite Valley, but it was not explored until 1855. For many years the valley could be reached only by the roughest trails, but as its advantages became more widely known roads were built, and there are now three different wagon routes by which it may be entered. The history of the Yosemite Valley is like that of all the other canons of the Sierra Nevada mountains. Long ago there were no high mountains in eastern California. If there had been explorers crossing the plains in those days, they would have found no rugged wall shutting them off from the Pacific. There came a time, however, when the surface of the western portion of America was broken by violent earthquake movements, and hundreds of fissures were formed. Some of the earth blocks produced by these fissures were shoved upward, while others were dropped. One enormous block, which was to form the Sierra Nevada, was raised along its eastern edge until it stood several thousand feet above the adjoining country. The movement was like that of a trap-door opened slightly, so that upon one side--in this case the western one--the slope was long and gentle, while upon the east it was very abrupt. [Illustration: FIG. 14.--THE YOSEMITE VALLEY] Nature, the sculptor, took this mountain block in hand, and with the aid of running water began to carve its surface into a most intricate system of canons and ridges. The streams first flowed over the easiest slopes to the Great Valley of California, but soon they began to cut their way down into the granite, while along the crests of the ridges the more resistant rocks began to stand out as jagged peaks. Thus Nature worked until the mountains promised before long to be well worn down. The canons had widened to valleys and the rugged slopes had given place to gentle ones. Toward the northern end of the range the work was even farther advanced, for the streams, now choked with gravel and sand, flowed over broad flood plains. In this gravel was buried a part of the wealth of California. The rocks over which the streams flowed contained veins of quartz with little particles of gold scattered through it, and as the surface rock crumbled and was worn away, the gold, being much heavier, slowly accumulated in the gravel at the bottom of the streams. This gold amounted in value to hundreds of millions of dollars.