Resources of the United States appears annually and makes known not only the figures of production but also the numerous theoretical considerations which interest the miner.
As to the geographic work which the Geological Survey also possesses among its attributes, a numerous personnel of topographers and engineers work actively at the execution of the map in the most diverse parts of the country under the direction of Mr. H. Gannett. Already more than six hundred sheets have been surveyed and drawn, and about four hundred have appeared.
Besides geology and geography ought to be mentioned a considerable work, of which Mr. Powell is the founder, in the domain of the pre-Columbian archæology, the linguistics, the ethnology, and the anthropology of the Indians of North America, splendidly illustrated by Mr. Holmes. The last publication of Mr. Powell upon the classification of American languages is, according to the best judges, of great importance.
Not being able to give here a complete list of all the actual collaborators of the survey, or of their services, we must content ourselves with noticing those who have taken the principal part in the execution of the works already published. These are in alphabetical order: Messrs. Becker, Chamberlin, Cross, Davis, Day, Diller, S. F. Emmons, Fontaine, Gannett, Gilbert, Hague, Hayes, Holmes, Iddings, McGee, Marsh, Newberry, Peale, Russell, Shaler, Van Hise, Walcott, Ward, Upham, Weed, C. A. White, Whitfield, A. Williams, G. H. Williams, and H. S. Williams. It is but just that we should not omit the names of those who are dead: Messrs. Hayden, Irving, Lesquereux, Leidy, Marvine, and Newton; or of those who no longer belong to the survey: Messrs. Bradley, Cope, Curtis, Dutton, Endlich, Hill, Howell, Clarence King, St. John, Stevenson, and Wheeler. Many of these names will remain justly illustrious.
It will be impossible to give in this report even a summary idea of the most remarkable discoveries which are due to the Geological Survey. They belong to branches very diverse: regional geology, monographs concerning metalliferous deposits, general and comparative stratigraphy, mineralogy and petrography, volcanic phenomena, glacial phenomena, ancient Quaternary lakes, and a history of the Atlantic littoral.
Among the most considerable results must be mentioned the paleontological discoveries made in the Rocky Mountains. Since the day in which Hayden undertook his memorable explorations, we have learned that the site of the Rocky Mountains was continuously a part of the continent during the greater portion of the Secondary, Tertiary, and Quaternary epochs. Upon this vast continent the quadrupeds could develop during extended time, freely, without any interruption to their evolution, and thus they
