With such great post series like where on google earth, geopuzzles, and the alliterative sea-floor Sunday, Friday faults, and Friday field foto, when not start out the week with map Monday?
The map is of the pluvial Lake Bonneville, completed during the Wheeler Survey, one of the large "west of the 100th meridian" surveys that helped to establish the USGS in the 1870s. The data for the map was gathered in part by the great 19th century geomorphologist, G. K. Gilbert. The map is part of the David Rumsey Map Collection. Click on the image for a larger look. If you also have time, check out this neat little flash "brief history of Lake Bonneville" from the Utah State Geological Survey.
Restored Outline Of Lake Bonneville. Geological Data By G.K. Gilbert & E.E. Howell. J. Bien lith. Portions Of Western Utah & Eastern Nevada. Expeditions of 1869, 1871, 1872 & 1873 Under the Command of 1st. Lieut. Geo. M. Wheeler, Corps of Engineers, U.S. Army. U.S. Geographical Surveys West Of The One-Hundredth Meridian. (1876)