Gizmo Surface with Contour

Ok, maybe this is easy and I'm just missing it, but the example under "Surface Plots" in Visualization.ihf shows a 3D surface with a contour map at the bottom of the graph. This is exactly how I want to display my data. How does one add a contour plot to the bottom (or preferably top) of a gizmo plot?
Thanks John!

I knew it had to be easy but didn't find anything on it!

Michael