16.4: What is a Geologic Cross-section?
What Is a Geologic Cross-section?
Remember that a geologic map will be seen in map-view. However, geologists use information about rocks that are exposed at the surface to visualize the unseen rocks beneath the surface, enabling them to also construct a cross-sectional view. A geologic cross-section illustrates how different types of rock are layered or otherwise configured, including geologic structures, such as folds and faults (Figure 16.4).
Figure 16.4: Geologic cross-section (A-A’-A”) from the northern section of the Alameda, Contra Costa, and San Francisco Counties, California geologic map. (Public Domain; R.W. Gramer/USGS Links to an external site.)