From 1867 practically to the end of the nineteenth century a series of geological surveys led by Clarence King (1842-1901), Ferdinand V. Hayden (1829-1887), and John Wesley Powell (1834-1902) explored and mapped the West. Carried out under the aegis of the U.S. Army Corps of Engineers, King's survey of the Fortieth Parallel (the "Great Basin" between the middle Rockies and the Sierra Nevada) in 1867 was mainly utilitarian in its objectives: King had justified the survey by claiming it would stimulate the discovery of mineral deposits. His books The Mining Industry (1870) and Systematic Geology (1878) were products of this survey.

Searching for Dinosaurs.

Hayden, who joined the Interior Department in 1867, organized a survey of the western territories, pushed for the establishment of Yellowstone Park (which was authorized in 1872), and became first director of what was then called the U.S. Geological...