In alpine areas, sediment is added to the surface of the glacier from the valley walls through various types of mass movement . Much of the debris that is added to the ice of the glacier is eventually delivered to the snout because of the continual forward flow of glacial ice. From the snout this material can be placed directly from the ice or it can be deposited through the action of flowing meltwater . Geomorphologists call the later deposits glaciofluvial deposits. The technical term used to describe material deposited by the ice is called till or moraine .
All glacial deposits are by and large known as glacial drift .
Till is a heterogeneous combination of unstratified sediments ranging in size from large boulders to minute particles of clay . When till is deposited along the edge of a glacier it tends to form irregular hills and mounds known as moraines . A terminal moraine is a deposit that mark, the farthest advance of a glacier. Moraine deposits created during halts in the retreat of the glacier are called recessional moraines . A till plain is a large, relatively flat plain of till that forms when a sheet of ice becomes detached from the main body of the glacier and melts in place.