I didn't see the earth map when i played the game. Did i just not look very hard or is it not an added feature yet?
Viewing post in Rivers, Lakes and Erosion comments
On the "Generate new world" dialog, check the box to use a custom heightmap, then click the 'select' button. It will open a file selection dialog. If you haven't added any heightmaps, then the only one should be the Earth heightmap: "CompositeEarth_3600x1800.png". Click "Load" to close the dialog. The Earth map should appear in the generate world dialog. You can now click "Generate" to generate a new world using the Earth map. Note that the import process is not perfect and you will need to edit the map to make it look like the actual Earth.