The Great Basin Desert is marked by wide flatness and is largely a region of ancient lake beds. Its surfaces are in many instances what the geologists term constructional, built up largely of great alluvial fans or piedmont allu vial plains, constituting the so-called filled val leys of the inter-montane belts. Its flora is mostly sage brush and grease wood; its agri cultural products are cereals and tubers, and minerals gold, silver and copper. The Sonoran Desert is of a more complicated geological type, and instead of being land-locked is bordered on one side by the Pacific Ocean. Some of its surfaces are also the result of what geologists term destructional processes. Its floral types are the saguara, palo verde and the cats claw. Its sparse agricultural products are fruit and wheat, its mineral resources gold and copper.
The Chihuahuan Desert, marked by parallel plains and ranges, is a relatively higher region; its features are a combination of destructional and constructional processes. Its floral types are the maguey cactus and yucca ; its chief agricultural product maize (corn), and its prin cipal mineral product silver.
While the desert plains may be extensive, they also have many phases of variation. There are the alkali plains, while crystal patches of saline efflorescence which vegetation abhors, and vast plains of edobys (adobe) brownish choc olate clay soils through which here and there are cut the deep channels of streamless streams, or arroyos. There are the dreary' atabose flats covered by the headlike bunches of a woody grass, abhorred by animals and useless to man, through which one may travel for days. The great white gypsum desert of the Tularosa Val ley of New Mexico is one of the most won drous of all the desert plains. To the eye it is a veritable sea of purest granular snow, marked with wind waves and ripples like the Tropic Ocean, with billows and troughs. In some places there are extensive lakes of crystalline salt which the desert inhabitant uses for herd and flock. Sometimes there are stretches of dreary brown sand hills, great billows gathered around the protecting roots of the thorny mes quite, the particles blowing with each breath of wind.
The half cannot be told of the many other aberrant features of the Great American Desert, like Death Valley; the great or white sand dunes just south of El Paso, each as high as the national capitol, which creep from place to place over the desert plain; the vast plains of malpais in New Mexico with their burning, cutting, black, waterless surfaces of' lava; the S'flour dust" deserts of Jimenez and Arizona and Sonora, where the traveler is choked with clouds of chalk-white powder; the Crow Flat with its glare that blinds; the Jornado del Muerto, with its hundred whirl winds; the saguara desert of Sonora, where for hundreds of miles grows no blade of grass.
The clouds are the most wonderful manifes tations of the desert heavens. The forms of vaporous atmosphere are numerous. In the morning they fill the valleys with snow white vapor, which at midday rises and gathers into solitary fluffs sailing majestically along. Some times showers freshen the desert. These are occasionally of sufficient volume to dampen the earth and vegetation, and an awakening of life ensues which is most remarkable. Vegetation seems to awaken instantaneously, plants which before were dry and dust-covered unfold into broad areas of vivid green. Coriaceous ferns, ordinarily lying like dead leaves among the stones, unroll and wave their fronds in the freshened air. From the inconspicuous flowers of the many thorny shrubs of the acacia and yucca tribe the air is laden with perfume. It would seem paradoxical to speak of the desert in bloom, but the human senses of sight and smell can be regaled by no more pleasant ex perience than the delicate odors and sweeps of color that sometimes follow an unusual rainfall.
Like a dainty pencil line drawn across the sheet of desert, the trails may be seen for miles and miles. These, originally made by the wild Comanche and Apache, lead in long tangents from water-hole to water-hole, cutting paths of deep-worn ruts. Were it not for these trails connecting the various water places the desert probably would be impassable, for the priceless water is usually concealed in spots where least suspected. These water-holes were discovered by the aborigines long before the ranchman and settler came or the army wagons and cavalry troops deepened the . impress of the trails. What stories of death and pain, thirst and star vation could be told by these old trails! We know that as early as 1528 many of them ex - isted, for in that year Cabeza de Vaca and his three shipwrecked survivors of the Narvaez ex pedition followed these paths from water-hole to water-hole across our southern border, and that modern commerce and migration still use these, the oldest and most stable monuments of the desert.