An elongated whale-shaped hill formed by glacial action. Its long axis is parallel with the movement of the ice, with the blunter end facing into the glacial movement. Drumlins are sometimes compared to kames, but their formation is distinctively different. A drumlin is not originally shaped by meltwater, but by the ice itself and has a quite regular shape. It occurs in fine grained material, such as clay or shale, not in sands and gravels. And drumlins usually have concentric layers of material, as the ice successively plasters new layers in its movement.