TO most Americans the southwest means the desert, and it is true that most of Arizona, New Mexico, and Utah, and portions of Colorado and southern California, are arid or semiarid lands, relieved, however, by regions of fertility and agricultural prosperity. In popular conception the desert has been the negative of all that means beauty, richness, and sublimity; it has been the synonym of poverty and death. Gradually but surely the American public is learning that again popular conception is wrong, that the desert is as positive a factor in scenery as the mountain, that it has its own glowing beauty, its own intense personality, and occasionally, in its own amazing way, a sublimity as gorgeous, as compelling, and as emotion-provoking as the most stupendous snow-capped range.
The American desert region includes some of the world’s greatest scenery. The Grand Canyon of the Colorado River is sunk in a plateau which, while sprinkled with scant pine, is nearly rainless. Zion Canyon is a palette of brilliant color lying among golden sands. A score of national monuments conserve large natural bridges, forests of petrified trees, interesting volcanic or other phenomena of prehistoric times, areas of strange cactus growths, deposits of the bones of monstrous reptiles, and remains of a civilization which preceded the discovery of America; and, in addition to these, innumerable places of remarkable magnificence as yet unknown except to the geologist, the topographer, the miner, the Indian, and the adventurer in unfrequented lands.
This arid country consists of rolling sandy plains as broad as seas, dotted with gray sage-brush and relieved by bare craggy monadnocks and naked ranges which the rising and the setting sun paints unbelievable colors. Here and there thin growths of cottonwood outline thin ribbons of rivers, few and far between. Here and there alkali whitens the edges of stained hollows where water lies awhile after spring cloud-bursts. Here and there are salt ponds with no outlet. Yet even in the desolation of its tawny monotony it has a fascination which is insistent and cumulative.
But the southwest is not all desert. There are great areas of thin grazing ranges and lands where dry farming yields fair crops. There are valleys which produce fruits and grains in abundance. There are hamlets and villages and cities which are among the oldest in America, centres of fertile tracts surrounded by deserts which need only water to become the richest lands on the continent. There are regions reclaimed by irrigation where farming has brought prosperity. In other places the plateau covers itself for hundreds of square miles with scrubby pine and cedar.
All in all, it is a land of rare charm and infinite variety.
To appreciate a region which more and more will enter into American consciousness and divide travel with the mountains, the reader should know something of its structural history.
The southwestern part of the United States rose above sea-level and sank below it many times during the many thousands of centuries preceding its present state, which is that of a sandy and generally desert plateau, five to ten thousand feet in altitude. How many times it repeated the cycle is not fully known. Some portions of it doubtless were submerged oftener than others. Some were lifting while others were lowering. And, meantime, mountains rose and were carried away by erosion to give place to other mountains which also wore away; river systems formed and disappeared, lakes and inland seas existed and ceased to exist. The history of our southwest would have been tempestuous indeed had it been compassed within say the life of one man; but, spread over a period of time inconceivable to man, there may have been no time when it might have seemed to be more active in change than its still hot deserts seem to-day to the traveller in passing trains.
Other parts of the continent, no doubt, have undergone as many changes; our southwest is not singular in that. But nowhere else, perhaps, has the change left evidences so plain and so interesting to the unscientific observer. The page of earth’s history is more easily read upon the bare deserts of our southwest than on the grass-concealed prairies of the Mississippi Valley or the eroded and forested ranges of the Appalachians.
Before the Rockies and the Sierra even existed, in the shallow sea which covered this part of the continent were deposited the ooze which later, when this region rose above the sea, became the magnificent limestones of the Grand Canyon. Muds accumulated which to-day are seen in many highly colored shales. Long ages of erosion from outlying mountain regions spread it thick with gravels and sands which now appear in rocky walls of deep canyons. A vast plain was built up and graded by these deposits. The trunks of trees washed down by the floods from far distant uplands were buried in these muds and sands, where, in the course of unnumbered centuries, they turned to stone. They are the petrified forests of today.
Mountains, predecessors of our modern Sierra, lifted in the south and west, squeezed the moisture from the Pacific winds, and turned the region into desert. This was in the Jurassic Period. Sands thou-sands of feet deep were accumulated by the desert winds which are today the sandstones of the giant walls of Zion Canyon.
But this was not the last desert, for again the region sank below the sea. Again for half a million years or more ooze settled upon the sands to turn to limestone millions of years later. In this Jurassic sea sported enormous marine monsters whose bones settled to the bottom to be unearthed in our times, and great flying reptiles crossed its water.
Again the region approached sea-level and accumulated, above its new limestones, other beds of sands. New river systems formed and brought other accumulations from distant highlands. It was then a low swampy plain of enormous size, whose northern limits reached Montana, and which touched what now is Kansas on its east. Upon the borders of its swamps, in Cretaceous times, lived gigantic reptiles, the Dinosaurs and their ungainly companions whose bones are found today in several places.
For the last time the region sank and a shallow sea swept from the Gulf of Mexico to the Arctic Ocean. Again new limestones formed, and as the surface very slowly rose for the last time at the close of the Cretaceous Period many new deposits were added to the scenic exhibit of today.
Meantime other startling changes were making which extended over a lapse of time which human mind cannot grasp. Responding to increasing pressures from below, the continent was folding from north to south. The miracle of the making of the Rockies was enacting.
During all of Tertiary times earth movements of tremendous energy rocked and folded the crust and hastened change. The modern Sierra rose upon the eroded ruins of its predecessor, again shutting off the moisture-laden western winds and turning the south-west again into a desert. One of the mountain-building impulses spread eastward from the Sierra to the Wasatch Mountains, but Nature’s project for this vast granite-cored table-land never was realized, for continually its central sections caved and fell. And so it happened that the eastern edge of the Sierra and the western edge of the Wasatch Mountains became the precipitous edges, thousands of feet high, of a mountain-studded desert which today is called the Great Basin. It includes southeastern Oregon, nearly all of Nevada, the western half of Utah, and a large area in the south of California, besides parts of Idaho and Wyoming. It is 88o miles north and south and 572 miles wide. Its elevation is five thousand feet, more or less, and its area more than two hundred thousand square miles.
This enormous bowl contained no outlet to the sea, and the rivers which flowed into it from all its mountainous borders created a prehistoric lake with an area of fifty-four thousand square miles which was named Lake Bonneville after the army officer whose adventures in 1833 were narrated by Washington Irving; but it was Fremont who first clearly described it. Lake Bonneville has evaporated and disappeared, but in its place are many salty lakes, the greatest of which is Great Salt Lake in Utah. Attenuated rivers still flow into the Great Basin, but are lost in their sands. The greatest of these, the Mohave River, is a hundred miles long, but is not often seen because it hides its waters chiefly under the surface sands. Lake Bonneville’s prehistoric beaches exist today. Transcontinental passengers by rail cross its ancient bed, but few know it.
The Great Basin today is known to travellers principally by the many lesser deserts which compose it, deserts separated from each other by lesser mountain ranges and low divides. Its southern and south-eastern boundaries are the plateaus and mountains which form the northern watershed of the muddy Colorado River and its confluents. South of the Colorado, the plateaus of New Mexico, Arizona, and southern California gradually subside to the Rio Grande.
During this period and the Quaternary which followed it, volcanoes appeared in many places; their dead cones diversify our modern landscape. It was during the Quaternary Period, in whose latter end lives man, that erosion dug the mighty canyons of our great southwest. The Colorado was sweeping out the Grand Canyon at the same time that, far in the north, the glaciers of the Great Ice Age were carving from Algonkian shales and limestones the gorgeous cirques and valleys of Glacier National Park.