Major J. W. Powell began his large contribution to Government surveys with his exploration of the Grand Canyon in 1869, the Congressional recognition of his expedition being limited to an authorization for the issue of rations by the War Department. Small appropriations were made in the following years, and in 1874 full authorization was given for the continuance of his survey in Utah under the Secretary of the Interior and was followed by the adoption of the name “United States Geographical and Geological Survey of the Rocky Mountain Region.” This organization was the least pretentious of the four operating during this period—it covered less area, expended less public money, and published much less—but its contribution to American geology is not to be measured by miles or pages but by ideas. Its physical environment favored this survey, and in the work of Powell, Dutton, and Gilbert can be seen the beginnings of physiography on the heroic scale exemplified in the Grand Canyon and the High Plateaus. The first use of terms like “base-level of erosion,” “consequent and antecedent drainage,” and “laccolith” marked the introduction of new ideas in the interpretation of land sculpture and geologic structure. The daring boat trip of Powell was no less brilliant than his simple explanation of the Grand Canyon itself. “The United States Geographical Surveys West of the 100th Meridian” was the title given to the explorations made under Lieut. G. M. Wheeler, of the Engineer Corps, which began with topographic reconnaissances in Nevada, Utah, and Arizona, specifically authorized by Congress in 1872. From the standpoint of American geology this could be better known as the Gilbert Survey, Mr. G. K. Gilbert serving for the three years 1871–73, the later part of the time with the title of chief geological assistant. Gilbert’s contributions included his description of Basin Range structure, his first account of old Lake Bonneville, and his discussion of the erosion phenomena of the desert country. J. J. Stevenson also served later as a geologist of this Survey, and A. R. Marvine, E. E. Howell, E. D. Cope, Jules Marcou, and I. C. Russell were connected with the field parties. Captain Wheeler’s own claim for the work of his Survey emphasized its geographic side, for he regarded the results as the partial completion of a systematic topographic survey of the country.