Fuel depots often require hydro contour plotting to determine the possible extent of contamination due to fuel leakage. Some you might loosely call stratigraphic in that it plotted the workable limits of a strata of mechanically competent material for a proposed quarry purchase. You never know what's going to come up.
So your mapping was all surface contours, or soil related. Nothing like this, I take it:
http://www.und.edu/instruct/mineral/101intro/grandcanyon/grandcan.htm