Many different types of maps exist to help us understand the world around us, whether it be the distribution of lakes and rivers or political boundaries. However, topographic and geologic maps are often used to delineate different physical features pertaining to the Earth’s surface.
Topographic maps are actually several different maps layered on top of one another. They graphically display a third dimension through contour lines used to depict changes in elevation. Each contour line represents its own level of equal elevation.
A geologic map, on the other hand, does not display a third dimension; instead, it shows the varying geologic features in an area that are under the ground, including rock types and faults. Typically printed on top of a regular map, or base map, geologic maps use symbols, colors and lines standard to geology.
The primary differences between the two lie in the fact that geologic maps display a third dimension in that they show elevations, while geologic maps only depict in two dimensions various rock formations that exist on a flat surface.