Hi Wheatpenny,

You can get some genuine height maps here: http://edc2.usgs.gov/geodata/

However, using the DEMs inside of Carrara will require using Digital Carvers Guild Ground Control.

I'd really be inclined to simply use Carrara's painting tools in the Terrain Editor or create a grayscale heightmap in Photoshop/PSP and simply import it into the Terrain Editor. 

Mark