The sage-brush country of California begins properly at the foot of the Sierras where the state-line sheers east by south from Lake Tahoe. It covers the high valleys that divide the true Sierra from the older, lesser ranges that keep it company as far south as Olancha. Below Mono Lake, that part of the gold region made immortal by Mark Twain, it gives to the chrome- and ochre-tinted soil its distinguishing characteristic. From the long arm of Death Valley it begins to be encroached upon by the mesquite, and at Indian Wells it is driven close under the lee of the last Sierra. The range of which San Bernardino and San Jacinto are outposts carries the artemisia farther desertward, almost to the Colorado River in fact, and south again about the Salton Sea it holds its own with sahuro and palo verde. Its eastern border, like that of the wild tribes along the Mojave line, is lost in pure desertness. Formerly much of that country from San Bernardino to the sea was native to the sage, and all the southern end of the San Joaquin. But now all this is replaced with orchards, for the artemisia proves nothing so much of the soil on which it grows as that, given a due allowance of water, it is as desirable for other things. [Illustration: THE HALF DOME, YOSEMITE] All this country which I have described to you has so recently been sea that the mark of its old beach-line is plainly to be traced along the east Sierra wall. Still the evaporating water leaves vast deposits of salt and alkali, blinking white in the sink of Death Valley. There are lakes there still where the salt crusts over hard and clear like ice, and deep thick puddles of bitter minerals, the lees of that ancient inland ocean. From the top of any of the denuded desert ranges it is possible to trace the winding bays and estuaries, and, with an eye for location, to choose the points at which one may fairly expect to find potsherds, amulets, fire-blackened hearthstones, and the middens of a nameless people who built their primitive towns along its beaches. It must have had much to recommend it in those days before the sage-brush took it, for this inland sea, rather than the more mountainous Pacific shore, was the route taken by the ancient migratory peoples who left their undecipherable signs scored into the rocks from the Aztec country to the Arctic. On isolated igneous rocks near their old encampments, and high on the walls of the box canons, such as might have been tide-rifts, high above any mechanical contrivance of the present-day Indians, the records resist equally the shifts of sea and sand and the efforts of modern science to read them.