The erosion device does a great job of simulating erosion from water run off. this gives the typical V shaped valley. I was wondering if could be the option to have a U shaped valley, similar to what you can see caused by glacial erosion. As a glacier slides down a hill it carves a nice U shape
You can see an example here http://icons.wunderground.com/data/wximagenew/s/snodog/443-800.jpg
