SketchUp is fully capable of doing so. (Wrong term though -- SketchUp uses 'drape' to describe something else. If you're searching the Users Guide, you don't want to search on that term.)
You want to 'project' a texture onto the terrain surface. This is described in one of the Google video tutorials here:
http://sketchup.google.com/gsu5vtvideos.html
(#12, "Using images as signs")
I've produced several textured terrains with projection, including a tutorial:
http://sketchup.google.com/3dwarehouse/cldetails?mid=2ff3fe050d0f83a549a70958796b8e8&num=50&scoring=d
Hopefully, one of these models provides the help you need.
Regards,
Taff