Report on the lands of the arid region of the United States, with a more detailed account of the lands of Utah

by John Wesley Powell; Willis Drummond; Clarence E. Dutton; Grove Karl Gilbert; A. H. Thompson

For the reasons so briefly stated, the question of the origin and permanence of the increase of the water supply is one of prime importance to the people of the country. If it is due to a temporary increase of rainfall, or any briefly cyclic cause, we shall have to expect a speedy return to extreme aridity, in which case a large portion of the agricultural industries of the country now growing up would be destroyed.

The increase is abundantly proved; it is a matter of universal experience. The observations of the writer thereon have been widely extended. Having examined as far as possible all the facts seeming to bear on the subject, the theory of the increase of rainfall was rejected, and another explanation more flattering to the future of agriculture accepted.

The amount of water flowing in the streams is but a very small part of that which falls from the heavens. The greater part of the rainfall evaporates from the surfaces which immediately receive it. The exceedingly dry atmosphere quickly reabsorbs the moisture occasionally thrown down by a conjunction of favoring conditions. Any changes in the surfaces which receive the precipitation favorable to the rapid gathering of the rain into rills and brooks and creeks, while taking to the streams but a small amount of that precipitated, will greatly increase the volume of the streams themselves, because the water in the streams bears so small a proportion to the amount discharged from the clouds. The artificial changes wrought by man on the surface of the earth appear to be adequate to the production of the observed effects. The destruction of forests, which has been immense in this country for the past fifteen years; the cropping of the grasses, and the treading of the soil by cattle; the destruction of the beaver dams, causing a drainage of the ponds; the clearing of drift wood from stream channels; the draining of upland meadows, and many other slight modifications, all conspire to increase the accumulation of water in the streams, and all this is added to the supply of water to be used in irrigation.

Students of geology and physical geography have long been aware of these facts. It is well known that, under the modifying influences of man, the streams of any region redeemed from the wilderness are changed in many important characteristics. In flood times their volumes are excessively increased and their powers of destruction multiplied. In seasons of drought, some streams that were perennial before man modified the surface of the country become entirely dry; the smaller navigable streams have their periods of navigation shortened, and the great rivers run so low at times that navigation becomes more and more difficult during dry seasons; in multiplied ways these effects are demonstrated. While in the main the artificial changes wrought by man on the surface are productive of bad results in humid regions, the changes are chiefly advantageous to man in arid regions where agriculture is dependent upon irrigation, for here the result is to increase the supply of water. Mr. Gilbert, while engaged during the past season in studying the lands of Utah, paid especial attention to this subject, and in his chapter has more thoroughly discussed the diverse special methods by which increase in the flow of the streams is caused by the changes wrought by man upon the surface of the earth. His statement of facts is clear, and his conclusions are deemed valid.

CHAPTER VI.
THE LANDS OF UTAH

PHYSICAL FEATURES.

A zone of mountains and high plateaus extends from the northern nearly to the southern boundary of Utah Territory. The Wasatch Mountains constitute the northern portion of this zone, the High Plateaus the southern. This central zone has a general altitude above the sea of from nine to eleven thousand feet. Many peaks are higher, a few reaching an altitude of about twelve thousand feet. On the other hand many cañons and valleys have been excavated by the running waters far below the general level thus indicated.

The Uinta Mountains stretch eastward from the midst of the Wasatch. This region is a lofty table land carrying many elevated peaks whose summits are from twelve to nearly fourteen thousand feet above the level of the sea. This is the highest portion of Utah, and among its peaks are the culminating points.

South from the Uinta Region, and from the southern extremity of the Wasatch Mountains, another elevated district extends east-southeast beyond the borders of Utah. This table land is cut in twain by two great gorges of the Green River—the Cañon of Desolation and Gray Cañon. The eastern portion is called East Tavaputs Plateau, the western West Tavaputs Plateau.

Between the Uinta Mountains and the Tavaputs table land is the Uinta-White Basin, a low synclinal valley, drained by the Uinta and its ramifications on the west, and the lower portion of the White River on the east.