Outlined topography in Cross Sections

[Morgan Silverman]

Hello,
I am plotting cross sections that show the surface topography in them. It's
hard to see where the topography is in the blank area though. Does anyone
know how I can create an outline of the topography in a cross section, so
that when the entire area above is not shaded it, you can still see where
the edge of the topography is? Thanks.
-Morgan