Sandstone blocks.
Salt-beds.
Sand-beds.
You may spend days and weeks studying the make-up of these desert-floors. Beyond Yuma on the Colorado there are thousands of acres of mosaic pavement, made from tiny blocks of jasper, carnelian, agate—a pavement of pebbles so hard that a horse’s hoof will make no impression upon it—wind-swept, clean, compact as though pressed down by a roller. One can imagine it made by the winds that have cut and drifted away the light sands and allowed the pebbles to settle close together until they have become wedged in a solid surface. For no known reason other portions of the desert are covered with blocks of red-incrusted sandstone—the incrustation being only above the sand-line. In the lake-beds there is usually a surface of fine silt. It is not a hard surface though it often has a crust upon it that a wild-cat can walk upon, but a horse or a man would pound through as easily as through crusted snow. The salt-beds are of sporadic appearance and hardly count as normal features of the desert. They are often quite beautiful in appearance. The one on the Colorado near Salton is hard as ice, white, and after sunset it often turns blue, yellow, or crimson, dependent upon the sky overhead which it reflects. Borax and gypsum-beds are even scarcer than the salt-beds. They are also white and often very brilliant reflectors of the sky. The sand-beds are, of course, more frequently met with than any others; and yet your horse does not go knee-deep in sand for any great distance. It is too light, and is drifted too easily by the winds. Bowlders, gravel, and general mountain wash is the most common flooring of all.
Mountain vegetation.
Withered grasses.
The mountains whence all the wash comes, are mere ranges of rock. In the canyons, where there is perhaps some underground water, there are occasionally found trees and large bushes, and the very high sierras have forests of pine belted about their tops; but usually the desert ranges are barren. They never bore fruit. The washings from them are grit and fry of rock but no vegetable mould. The black dirt that lies a foot or more in depth upon the surface of the eastern prairies, showing the many years accumulations of decayed grasses and weeds, is not known anywhere on the desert. The slight vegetation that grows never has a chance to turn into mould. And besides, nothing ever rots or decays in these sands. Iron will not rust, nor tin tarnish, nor flesh mortify. The grass and the shrub wither and are finally cut into pieces by flying sands. Sometimes you may see small particles of grass or twigs heaped about an ant-hill, or find them a part of a bird’s nest in a cholla; but usually they turn to dry dust and blow with the wind—at the wind’s will.
Barren rock.
Mountain colors.
The desert mountains gathered in clusters along the waste, how old and wrinkled, how set and determined they look! Somehow they remind you of a clinched hand with the knuckles turned skyward. They have strength and bulk, the suggestion of quiescent force. Barren rock and nothing more; but what could better epitomize power! The heave of the enormous ridge, the loom of the domed top, the bulk and body of the whole are colossal. Rising as they do from flat sands they give the impression of things deep-based—veritable islands of porphyry bent upward from a yellow sea. They are so weather-stained, so worn, that they are not bright in coloring. Usually they assume a dull garnet-red, or the red of peroxide of iron; but occasionally at sunset they warm in color and look fire-red through the pink haze.