The following is a link to a document listing the height maps that ship with the game:
SB Maps
The height maps are just the elevation or relief data for that area. There is a map editor with which a wide variety of themed (woodland winter or Australian, e.g.) vegetation can be painted onto the relief data to create a terrain map. A good number of terrain maps are included as well. While the terrain maps can be altered, changed, or improved in the editor, the height maps cannot. There are, however, a small number of maps floating about that are not part of the initial release.
Given the variety of height maps, the versatility of the map editor, the number of themes, and sufficient time, any non-urban area (there are very few man-made objects available in the editor), except maybe the polar ice caps, could be simulated.