Digitial elevation model (DEM) from USGS with 70 m cell resolution. U.S. Geological Survey ( USGS) Digital Elevation Model (DEM) data files are digital representations of cartographic information in a raster form. DEMs consist of a sampled array of elevations for a number of ground positions at regularly spaced intervals. The 70m DEM is equivalent to the 15-minute DEM data which corresponds to the USGS 1:63,360-scale topographic quadrangle map series of Alaska by unit size.