Moraine

Moraine, a term adopted from the French for the rocky material carried downwards on the outside of a glacier, and deposited at its sides and foot. The position of the moraine with regard to the glacier is indicated by the names applied to it. The lateral moraine is the fringe of rock fragments at the glacier side. The glacier is always slowly moving down the valley. There are always points in the valley where rock falls are more frequent than in other places. The glacier as it moves forward catches this material and carries it onward in a long heaped line distributing it evenly all down the valley sides. When two glacial valleys converge into one valley two lateral moraines unite at the point of junction and form a median moraine in the resultant broader glacier, which now has two lateral moraines and one median. All this material carried by the glacier is deposited where the glacier ends, and forms the terminal moraine, frequently in the form of a crescentic dam across the valley. This material is carried farther downwards by stream action and distributed; otherwise the end of all glacier valleys would be blocked with debris against which the ice would be piled to a great height, and the glacier would finally become stationary. The material pushed forward beneath the glacier is sometimes called the ground moraine, the part left beneath the ice the lodge moraine, that carried to the edge and dropped the dump moraine, and that carried forward the push moraine. (See GLACIER.)