Page:Popular Science Monthly Volume 46.djvu/511

Rh survey. If agreeable to the States, co-operation will be continued on essentially the same conditions in the future as in the past.

—The work of the Geological Survey touches the interests of the agriculturist by furnishing data in relation to the distribution and supply of mineral manures, marls, phosphates, etc., and the distribution of soils. The soils are the direct result of the decay of rocks, and in the nonglaciated areas of the United States the geological maps, showing the distribution of the rocks, are practically soil maps, as the clay, lime, sand, and other constituents of the rocks are the chief ingredients of the soils. The maps of the superficial deposits within the glaciated region will show the distribution of the different types of soils produced during the drift period, and those of the deposits without the glaciated region, the drift materials deposited in the river valleys.

In the arid and semi-arid region all questions of the occurrence and distribution of artesian water and water supply for irrigation are of great importance to the farmer, and a knowledge of the underlying geology will be of service in determining extended systems of drainage in areas provided with abundant water supply by precipitation. The study of the materials entering into the construction of highways is also of moment to the farmer, as good roads mean so much to his industrial and social development.

It is not practicable adequately to summarize in a few paragraphs the results of the work of the survey for the period 18791894. A somewhat full statement has been made in the fourteenth and fifteenth annual reports of the director of the survey. But, in brief, it may be said that there are completed of topographic surveys, six hundred and eight thousand six hundred and fifty square miles, of which five hundred thousand are available for areal geologic mapping; of geologic mapping, one hundred thousand square miles, of which sixty thousand are ready for the engraver; of special geologic and miscellaneous investigations, fifteen large annual reports, one hundred and sixteen bulletins, and twenty-four monographs. Many thousand topographic and special geologic maps have been printed and distributed, and, what is most important, a material and intellectual equipment has been assembled that will have a marked influence in all future work.

Under the statutes the function of the Geological Survey is to make a topographic and geologic map of the United States, and to continue the examination of its geologic structure and mineral