Digital Elevation Model Map

Source: http://tahoe.usgs.gov/DEM.html

A digital elevation model or DEM is a digital topographical map, or a map that displays surface relief. They can be created using a number of different methods from traditional surveying to remote sensing equipment, like satellites. The map below is the Lake Tahoe basin. It was created using a bathymetric elevation model. This map is black and white verse color. Whites and lighter colors represent higher elevations.