Prevailing winds.
On the western portions of the Colorado the wind comes from the Pacific across Southern California. The hot air from the desert goes up and out over the Coast Range, reaching seaward. How far out it goes is unknown, but when it has cooled off it descends and flows back toward the land as the daily sea-breeze. It re-enters the desert through such loop holes in the Coast Range as the San Gorgonio Pass—the old Puerta de San Carlos—above Indio. The rush of it through that pass is quite violent at times. For wind is very much like water and seeks the least obstructed way. Its goal is usually the hottest and the lowest place on the desert—such a place, for example, as Salton, though I am not prepared to point out the exact spot on the desert that the winds choose as a target. On the Mojave Desert at the north their action is similar, though there they draw down from the Mount Whitney region as well as from the Pacific.
Wear of the winds.
Erosion of mountains.
In open places these desert winds are sometimes terrific in force though usually they are moderate and blow with steadiness from certain directions. As you feel them softly blowing against your cheek it is hard to imagine that they have any sharp edge to them. Yet about you on every side is abundant evidence of their works. The sculptor’s sand-blast works swifter but not surer. Granite and porphyry cannot withstand them, and in time they even cut through the glassy surface of lava. Their wear is not here nor there, but all over, everywhere. The edge of the wind is always against the stone. Continually there is the slow erosion of canyon, crag, and peak; forever there is a gnawing at the bases and along the face-walls of the great sierras. Grain by grain, the vast foundations, the beetling escarpments, the high domes in air are crumbled away and drifted into the valleys. Nature heaved up these mountains at one time to fulfil a purpose: she is now taking them down to fulfil another purpose. If she has not water to work with here as elsewhere she is not baffled of her purpose. Wind and sand answer quite as well.
Rock-cutting.
Fantastic forms.
But the cutting of the wind is not always even or uniform, owing to the inequalities in the fibre of rock; and often odd effects are produced by the softer pieces of rock wearing away first and leaving the harder section exposed to view. Frequently these remainders take on fantastic shapes and are likened to things human, such as faces, heads, and hands. In the San Gorgonio Pass the rock-cuttings are in parallel lines, and occasionally a row of garnets in the rock will make the jewel-pointed fingers of a hand protruding from the parent body.[3] Again shafts of hard granite may make tall spires and turrets upon a mountain peak, a vein of quartz may bulge out in a white or yellow or rose-colored band; and a ridge of black lava, reaching down the side of a foot-hill, may creep and heave like the backbone of an enormous dragon.
Wash-outs.
Sand-lines in caves.