The Pike's Peak boom was only one in a series of mining episodes which, within fifteen years of the discoveries in California, let in the light of exploration and settlement upon hundreds of valleys scattered over the whole of the Rocky Mountain West. The men who exploited California had generally been amateur miners, acquiring skill by bitter experience; but the next decade developed a professional class, mobile as quicksilver, restless and adventurous as all the West, which permeated into the most remote recesses of the mountains and produced before the Civil War was over, as the direct result of their search for gold, not only Colorado, but Nevada and Arizona, Idaho and Montana. Activity was constant during these years all along the continental divide. New camps were being born overnight, old ones were abandoned by magic. Here and there cities rose and remained to mark success in the search. Abandoned huts and half-worked diggings were scars covering a fourth of the continent. Colorado, in the summer of 1859, attracted the largest of migrations, but while Denver was being settled there began, farther west, a boom which for the present outdid it in significance. The old California trail from Salt Lake crossed the Nevada desert and entered California by various passes through the Sierra Nevadas. Several trading posts had been planted along this trail by Mormons and others during the fifties, until in 1854 the legislature of Utah had created a Carson County in the west end of the territory for the benefit of the settlements along the river of the same name. Small discoveries of gold were enough to draw to this district a floating population which founded a Carson City as early as 1858. But there were no indications of a great excitement until after the finding of a marvellously rich vein of silver near Gold Hill in the spring of 1859. Here, not far from Mt. Davidson and but a few miles east of Lake Tahoe and the Sierras, was the famous Comstock lode, upon which it was possible within five years to build a state.