Moraines
When a glacier melts, glaciers deposit unsorted ridges of till called moraines. Terminal moraines are found along the edge where the retreating glacier melts, and lateral moraines are located parallel to the direction of a valley glacier flow. In its steady state, a glacier is always carrying sediment to its snout and leaving it there, where it piles up like this in a terminal moraine. Advancing glaciers push the end moraine further, perhaps smearing it out and running it over, but retreating glaciers leave the end moraine behind.
In this picture represents a Terminal Moraine. It is located in Nellie Juan Glacier, Alaska. This was retreated during the 20th century. When a glacier melts, glaciers deposit unsorted ridges of till that flow into a area full of water.