Challis, Idaho - 30x60 Minute Series Topo Map Architecture These aerial photographs will be

These aerial photographs will be useful for professionals involved with geologic

The Colorado crosses the most structural barriers of any river in the western hemisphere

Central Utah Thrust Belt

The Vernon NE quadrangle covers a part of the floor of Rush Valley northeast of the Vernon Hills in southeastern Tooele County

The searchable catalog on this CD does not include data from 988 sample sites that have township and range coordinates only

Challis, Idaho - 30x60 Minute Series Topo Map Architecture These aerial photographs will beThe distinctive characteristic of a topographic map is that the shape of the Earth's surface is shown by contour lines. Contours are imaginary lines that join points of equal elevation on the surface of the land above or below a reference surface, such as mean sea level. Contours make it possible to measure the height of mountains, depths of the ocean bottom, and steepness of slopes. A topographic map shows more than contours. The map also includes