Page:U.S. Department of the Interior Annual Report 1877.djvu/46

XLIV an area of twenty-eight thousand square miles. In accordance with instructions from this department, stone monuments were built at all the important geodetic stations for the use of the surveyors of the public lands under the Commissioner of the General Land Office. The entire number thus erected was two hundred and twenty-five.

As soon as the topographical work is sufficiently advanced, a chart will be prepared showing the location of all the monuments in relation to such of the public lands as are suitable for arable purposes. Very careful attention was given to the study and classification of all areas suitable for arable, pastoral, or mining purposes, and materials were secured for a detailed economic map of the area surveyed, showing the different classes of land by a series of colors. Much attention was given to the measurement of the volume of water in the more important streams for the purposes of irrigation, also to the accumulation of water in reservoirs and the sinking of artesian wells. The possible methods for the redemption of what are called the “barren lands” were examined with great care.

A party was organized during the past season for the purpose of making a critical study of doubtful points in the geological structure of the Rocky Mountain region, and the results have been of the most gratifying character. Numerous facts were obtained which confirmed, in a remarkably clear manner, the statements that had already been made by the chief geologist, that while certain of the grand divisions or groups of strata possessed each certain peculiar characteristics and are recognizable with satisfactory distinctness as general divisions, they really constitute a continuous series of strata with no well-defined planes of demarkation, stratigraphical or paleontological.

A very large collection of fossils, as shells, fishes, insects, plants, &amp;c., were obtained, many of which are new to science. These collections constitute valuable standards for reference in the discussion of the various questions that must arise in the preparation of the geological reports.

One interesting feature of the work of the survey during the past season was the careful examination of the probable ancient outlet of the great lake that filled the Salt Lake Basin. It is probable that the waters flowed northward by way of Marsh Creek into the Portneuf, thence into the great Shoshone or Snake River, and thence into the Columbia River. The source of Marsh Creek is in the lowest pass between the drainage of the Great Basin and that of Snake River.

The publications of the survey during the past year have been quite voluminous, consisting of over 6,000 pages octavo and 2,000 pages quarto, with a great number of illustrations.

Those volumes which are in an advanced state of preparation are two quarto volumes on the vertebrate fossils of the West, one on the fossil insects, and one upon the Rhizopods, certain forms of microscopic life that have had greater influence in building up the crust of the earth