moulin

A nearly vertical cavity in a glacier through which meltwater from the surface drops into tunnels that are within or beneath the ice.

A nearly vertical shaft or cavity worn in a glacier by the running down of water, which sometimes in the hot days of summer, on the large glaciers, forms considerable rivulets on the surface of the ice.

A cylindrical, vertical shaft that extends through a glacier and is carved by meltwater from the glacier’s surface.