How to make glacial erosion

In my previous topic, I wanted to find a way of making the branching pattern found in real mountain ranges. I found that using two erosion devices (one with channeling and the other without) can come close to this. However, the channels created simply lack the depth and width of real life ridges. It seems that most such valleys are formed by glacial erosion, such as in the aptly named glacier national park. The park has ‘u’ shaped valleys with steep cliff sides. Even the northern Appalachian range in Vermont, New Hampshire, and Maine show signs of glacial erosion, with large ‘bowls’. Notice the sides of the mountain in the picture below. I cant find any way of replicating such erosion procedurally.

Your product is beautiful.

Could we use world machine to make a 4D?