Page:U.S. Department of the Interior Annual Report 1878.djvu/35

Rh the whole very satisfactory. About 12,000 square miles of very difficult country were surveyed, much of it in minute detail, and a mass of observation secured for the twelfth annual report, which will make it of more general interest and value than any of the preceding.

The district assigned to this survey by this department for the next Atlas comprises all the area of the Territories of the United States north of latitude 41° 45', east of meridian 117° and west of meridian 94°. It is estimated that the mapping of this area will occupy five years more, and when this is completed, the survey will have mapped over one-fourth the territory of the United States west of the one hundredth meridian.

Major Powell reports that early in July the parties of this survey again took the field. A new base-line has been measured at Kanab, in Southern Utah, on ground better adapted to the requirements of the trigonometric operations than the one formerly established in that vicinity. This line has been connected with the one previously measured at Gunnison by a complete chain of triangles having artificial points. Thus a geodetic basis has been given to the whole geographic work south of the 40th parallel sufficiently refined for all the purposes for which the survey is made.

The topographic and geologic work has been prosecuted south and east of the Colorado River. District 106 has been completed and much work done in district 105. The topographic methods employed were essentially the same as those of the previous season, that is, the plane-table and orograph were used in conjunction, the results of each being complementary to the other.

The hypsometric work rests on the base at Kanab, which had been previously established by long series of barometric observations.

The region surveyed embraces the elevated plateaus south of the Grand Cañon of the Colorado, and the plateaus and desert valleys stretching to the eastward. Very little irrigable land has been found, less than one-fourth of one per cent., as the tributaries of the Colorado are all very small and the great river itself runs at a profound depth below the general surface of the country, so that it cannot be used. Extensive and valuable grazing lands are included in the survey and some valuable forests of pine, spruce, and fir, the extent and characteristics of which have been carefully determined.

As the work has progressed from year to year it has been found that important economic questions relating to the future industries of the far West demanded more thorough investigation. The mineral resources, the extent, and practicability of the irrigable lands, pasturage lands, and timber lands have been regarded as questions of prime importance, and the researches of the survey have been more and more directed to their solution.
 * 31