Advances are characterized by a convex-shaped terminus. Glacial drift is the loose and unsorted rock debris distributed by glaciers and glacial meltwaters. Collectively, these deposits are called glacial drift . Till refers to the debris deposited directly by the glacier. Rock debris rolls off the glacier edges and builds piles of loose unconsolidated rocks called glacier moraine .
Lateral moraines form along the side of a glacier and curl into a terminal moraine .
Its presence turns lake water aqua blue or brown, depending on its parent rock type. Coarser rocks may gouge scratches called striations . Retreat results when the glacier is ablating at a rate faster than its movement downvalley. Retreating termini are usually concave in shape. A glacier is a body of ice showing evidence of movement as reported by the presence of ice flowline, crevasses, and recent geologic evidence.