The Great Basin Desert is the largest U. S. desert, covering 190,000 square miles. It is bordered by the Sierra Nevada Range on the west and the Rocky Mountains on the east, the Columbia Plateau to the north and the Mojave and Sonoran deserts to the south. The Great Basin Desert, unlike the Mojave or Sonora deserts, characteristically "lacks Creosote Bush" and was defined for the purposes of a 1986 report by J. Robert Macey who distinguished "Great Basin Scrub desert" versus "Creosote Bush desert". Rainfall within the Great Basin Desert region varies from 7 - 12 inches of rainfall per annum, and includes several arid basins without Larrea tridentata (chaparral) such as the "Chalfant, Hammil, Benton and Queen valleys", as well as all but a southeast portion of the Owens Valley. Conversely,