Landforms of the Great Basin

In 1964, biogeographer Edwin Hammond classified landforms in the United States by manually interpreting 1:250,000-scale topographic maps. Using a 93-square-kilometer neighborhood analysis window, he determined three input variables: slope, local relief, and profile. Unique combinations of these variables defined landform classes. By grouping the landform classes, Hammond identified five landform types: Plains, Tablelands, Plains with Hills or Mountains, Open Hills & Mountains, and Hills & Mountains. In 1991, this method was automated by Richard Dikau, Earl Brabb, and Mark Robert with GIS tools. They classified landforms in New Mexico using 200-meter digital elevation data and a 96-square-kilometer analysis window. The delineation of landforms in the Great Basin was implemented using this approach. Their algorithm was translated into a geoprocessing model in ModelBuilder for ArcGIS Desktop 9.1 and executed using the 30-meter National Elevation Dataset and a 1-square-kilometer circular analysis window. The model derived 21 landform classes in the Great Basin. Those classes were grouped into the final landform types. This map identifies seven landform types by expanding Hammond’s Plains and Hills & Mountains landform types.

Courtesy of U.S. Geological Survey.