Spectacular geological map of the region, colored based upon the mineralogical content of the region. Centered headwaters of the South Platter River, and showing Pueblo, Greenhorn Station, Colorado Springs in the East and Gunnison in the West. In 1869 Hayden was given a large appropriation and made head of the United States Geological Survey of the Territories. The biggest and best-known of the Great Surveys. The primary purpose of the expeditions to the Rocky Mountains was to evaluate the geological and mineral content of the regions. In addition to his interest in western minerals, Hayden was also one of the first to see the West as the land of the nature-loving tourist. In 1871 Hayden made an expedition into the Yellowstone Geyser Region resulting in spectacular photographs taken by William H. Jackson. The Yellowstone expedition made Hayden famous, but perhaps his most important was the detailed exploration and mapping of Colorado. Here his teams worked through some of the most rugged country in the West to complete the masterful Atlas of Colorado.