I had to do this glacial scene as part of a series on the history of the earth. I've also included, for whatever interest it may have, the heightfield map I used. The area the image was rendered from is in the upper left-hand corner. You can see the two gradated areas that produced the slope. (I don't think this is the final version of the map, now that I look at it. The crevasses in the glaciers aren't there.)
(http://black-cat-studios.com/glacier.jpg) (http://black-cat-studios.com/glacierdemo2.bmp)