The desert

by John C. Van Dyke

The foot-hills are just what their name indicates—the hills that lie at the foot of the mountains. They are not usually detached from the main range like so many of the lomas, but are a part of it; and while not exactly the buttresses of the mountains, yet they remind one of those architectural supports of cathedral walls. The foot-hills themselves are perhaps as firmly supported as the mountains for very often they stretch down from the mountains in a long ridge like a spine, and from the spine are thrown out supporting ribs that trail away into the valleys. In a granite country these foot-hills are usually very smooth, and are made up largely, as regards their surfaces, of the grit and grind of the rocks. The rocks themselves are usually wind worn, rounded by rain and sand, and sometimes fantastic in shape. Often the soft granite wears through in seams and leaves lozenge-like blocks linked together like beads upon a string; often the whole rock-crown of the hill is honey-combed by the wind until it looks as soft as a sponge. The foot-hills of porphyry are more jagged and rough in every way. The stone is much harder and while it splits like granite and falls along the mountain-side in a talus it does not readily disintegrate. The last bit of it remains a hard kernel, and the porphyry foot-hill is usually a keen-edged mountain in miniature.

Mountain-plants.

Bare mountains.

The hills have a desert vegetation of grease wood, cactus, and sage, with occasional trees like the palo verde and the lluvia d’oro; but their general appearance is not very different from the mesas. Where the altitude is high—say five thousand feet and over—there may be a more radical change in vegetation; for now the oak begins to appear, and if it is open country the grasses and flowers show everywhere. Sometimes the foot-hills are covered with a dense chaparral made up of many low trees and bushes; but this growth is more peculiar to the Californian hills west of the Coast Range than to Arizona. Many of the ranges in the Canyon country are almost as bare of vegetation as an ancient lake-bed. And sometimes altitude seems to have little to do with the kinds of growths. Cacti and the salt-bush flourish at six thousand feet as readily as down in the Salton Basin three hundred feet below sea-level. The most dangerous and difficult thing to set up about anything in this desert world is the general law or common rule. The exception—the thing that is perhaps uncommon—comes up at every turn to your undoing.

The southern exposures.

Gray lichens.

Even the mountains of Arizona that have an elevation of from five to eight thousand feet are often quite bare of timber. The sahuaro, the nopal, the palo verde may grow to their very peaks and still make only a scanty covering. Seen from a distance the southern exposure of the mountain looks perfectly bare; but if you travel around it to the north side where the sunlight does not fall except for a few hours of the day, you will find a growth of bushes, small trees, vines, and grasses that, taken together, form something of a thicket—that is for a desert. And here, too, on the northern exposure you will find the abrupt walls of the peak stained with great fields of orange and gray lichens that lend a color quality to the whole top.

Still in the desert region.

Arida zona.

But through the bushes and grasses and lichens the wine-red of the porphyry comes cropping out to tell you that the mountain is a mass of rock, that it holds little or no soil on its sides, that it has not a suspicion of water; and that whatever grows upon it, does so, not by favor of circumstance, but through sheer desert stubbornness. The vegetation is a thin disguise that is penetrated in a few moments. The arid character of the mountain says plainly enough that we are not yet out of the region of sands and burning winds and fiery sun-shafts. The whole of the Arizona country as far east as the Continental Divide, in spite of its occasional green valleys and few high mountain-ranges with timbered tops, is a slope leading up and out from the desert by gradual if broken steps which we have called mesas or benches. It is a bare, dry land. Its name would imply that the early Spaniards had found it that and called it arida zona for cause.[8]