Geologic and Topographic Mapping

What is a Geologic Map?

Geologic maps are not like other maps. Geologic maps, like all maps, are designed to show where things are. But, whereas the maps we know the best show the distribution of roads, rivers, or county boundaries, a geologic map shows the distribution of geologic features, including different kinds of rocks and faults. A geologic map is usually printed on top of a regular map (called a base map) to help you locate yourself on the map. The base map is printed with light colors, so it doesn’t interfere with seeing the geologic features on the map. The geology is represented by colors, lines, and special symbols unique to geologic maps. Understanding these features will allow you to understand much of the geology shown in almost any standard geologic map.

What is a Topographic Map?

If you were to fly over an area in an airplane and look down, the view you would see would be the map, or plan, view. Topographic maps are maps in which the three-dimensional configuration of the Earth’s surface, i.e., where the hills and valleys are, are represented on a flat, two-dimensional map. From topographic maps, we can determine an area’s relief (the difference in elevation between the high and low points). Topographic maps are used by surveyors, engineers, geologists, and other physical scientists, as well as hikers, hunters, and campers. Topographic maps also show roads, railroads, and political boundaries.