If you want it to look immense, the contour lines will need to be intricate down to a very small scale. I'm guessing there's probably a filter for GIMP or another program that can take simple lines and fractally twist them.

I did a quick mock up of the mountains on the SW continent. Ran a fractilize line script for gimp on one section. Spat out this.

Click image for larger version. 

Name:	elevation.jpg 
Views:	57 
Size:	50.3 KB 
ID:	66484

This make it look more immense?