Digital elevation models (DEMs) are arrays of elevation data that are geographically referenced. Four types of DEMs are available from the U.S. Geological Survey: 5 minute, 30 arc-second, 3 arc-second and 1 arc-second resolutions. Each type of DEM is available for free on the worldwide web and can be arranged using the program Arc/Info. Once these DEMs have been downloaded, they can be manipulated in a number of ways, including hillshading. Hillshaded DEMs can be used like stereoscopic photographs to teach geomorphology in the lab or classroom setting because they are three-dimensional models of the earth’s surface. When you look at a hillshaded DEM, you can see the surface of the earth stripped of vegetation, roads, buildings and other obstructions. DEMs are very good at highlighting landscape features that commonly are not visible on a standard 7.5’ topographic map because the vertical resolution far exceeds the contour interval of topographic maps. When used in conjunction with a geologic map, students can clearly see the relationship between bedrock and topography.