Geologic Cross Sections?
A third standard geologic
diagram is a cross section, which views the earth as if it were cut open and seen
from the side. Geologic cross sections are interpretative, since the relations
can generally not be observed directly. Only in areas of deep canyons or high
mountains can natural cross sections be observed. In most cases cross sections
require inference about subsurface structure. Sometimes drill holes or geophysical
exploration provide data from which cross sections can be constructed.
Look at the cross-sections on page 5 and page 15a of Rocks, Rails and Trails as examples of this
type of geologic diagram.