1873 Wheeler Map of Southern Nevada, Boulder Canyon and Las Vegas Region

An interesting pair of geologic maps of the American West, displaying the region around the Colorado River at Boulder Canyon, not far from the future city of Las Vegas. They were produced by the Wheeler Survey c. 1873 and published in the Topographical Atlas, which summarized the survey's work.

A Closer Look

Though presented side-by-side, the map at left depicts an area just to the north of the map at right, so that they together cover a continuous area running north to south between the 35th and 39th parallel north in the vicinity of the 114th parallel west. Today, this region sits to the east and northeast of the city of Las Vegas. The Colorado River is prominent in the map at right, including Boulder Canyon, later the site of Hoover Dam. Chromolithography is employed to distinguish rock by type and era. Aside from geographic features such as mountains, rivers, creeks, and springs, signs of human settlement, including roads, mines, telegraph lines, and towns also appear.

The Wheeler Survey, 1872 - 1879

One of the 'Four Great Surveys' of the American West, the expedition led by U.S. Army officer George Montague Wheeler was tasked with creating geologic and topographic maps of the territory west of the 100th meridian at the scale of eight miles to one inch. Like the other three 'great surveys' that took place around the same time, led by Clarence King (Fortieth Parallel Survey), John Wesley Powell (Green and Colorado Rivers, including the Grand Canyon), and Ferdinand Vandeveer Hayden (U.S. Geological and Geographical Survey of the Territories, focusing on the Yellowstone Region), the Wheeler Survey collected a wide range of information on Native American cultures (including early photographs), flora, fauna, and other topics in addition to its surveying work. Veterans of these expeditions went on to illustrious careers in the military, geology, cartography, photography, painting, and other fields. In 1879, Congress formally merged these projects to create the U.S. Geological Survey.

Chromolithography

Chromolithography, sometimes called oleography, is a color lithographic technique developed in the mid-19th century. The process involved using multiple lithographic stones, one for each color, to yield a rich composite effect. Oftentimes, the process would start with a black basecoat upon which subsequent colors were layered. Some chromolithographs used 30 or more separate lithographic stones to achieve the desired product. Chromolithograph color could also be effectively blended for even more dramatic results. The process became extremely popular in the late 19th and early 20th centuries, when it emerged as the dominant method of color printing. The vivid color chromolithography produced made it exceptionally effective for advertising and propaganda imagery.

Publication History and Census

This map was prepared by Grove Karl Gilbert, Arch R. Marvine, Edwin Eugene Howell, and George Montague Wheeler, based on surveys conducted in 1871 - 1873. It was lithographed by Weyss, Herman, and Lang, almost certainly employees of Julius Bien, for publication in the work Topographical Atlas Projected to Illustrate United States Geographical Surveys West of the 100th Meridian of Longitude, published between 1876 and 1881. In addition to the present, chromolithographed printing, examples exist of a map by the same title printed in black-and-white which provides a wider view of the U.S. Southwest, without the information on rock layers and ages. Regardless of printing, the map is only independently cataloged by Brigham Young University and the University of Wisconsin-Milwaukee, while the entire Atlas is more widespread.