Back and forth!

The glacier deposits and moves all rock debris that it tears from the mountain to the rhythm of these advances and subsequent retreats. These mounds are called “lateral moraines” when they are deposited on the sides of the glacier and “frontal moraines” when they are on the former glacial front. Behind the rock bars and moraines, glacial lakes can form. They generally disappear as a result of the filling or splitting of the dykes created by the moraines.