How do you change the material of a toposurface?

This post is regarding one particular query, you can see the full list by clicking here.

The material that is displayed when a Toposurface is cut in section can be changed under the Massing & Site Tab in the ribbon. There should be a small arrow pointing down and right near the section heading Model Site.

Pressing this arrow brings up a dialogue. There is a section of this dialogue titled Section Graphics. Changing the Section Cut Material will change what is displayed what a section cuts through the toposurface. Changing the Elevation of poche base will change the depth this material is displayed to - i.e. its thickness