The location of the outcrop is pinpointed on the base map and the elevation of the contact recorded. As information is plotted on the base map, the points are connected with a line that symbolizes the contact between rock units. In some areas of Kansas, aerial photographs are useful for locating outcrops and for interpretation. Certain vegetation types or patterns may be related to the underlying bedrock and can be utilized in mapping. Soils maps also are useful because some soil types are characteristic of a specific bedrock unit that is near the surface.
Geologic maps are compilations of data and inference.
Because outcrops may be a mile or more apart, geologists must use their training and experience to connect the data points by extrapolating and interpreting what happens between the scattered points of information. The geologist's job is to visualize the bedrock near the surface without the soil cover and to make a map that reflects this image. Once field work is complete and the field maps finalized, the data are entered into a computer. This scale is most appropriate for general-purpose use at the county level.