Moraine.

Moraine. The masses of rock which, by atmospheric action, are separated from the mountains bounding the valleys along which glaciers flow, find a temporary resting-place on the surface of the ice, at the margin of the glacier, and are carried along with it, but so slowly that they form a continuous line along each margin. These lines of debris are called lateral moraines. When two glaciers unite, the two inner moraines unite also and form one large trail in the middle of the trunk glacier, and this is called a medial moraine. A large portion of these rocky fragments at length reach the end of the glacier, and here the melting ice leaves it as a huge mound, which is known as a terminal moraine. The rock-debris, sand, clay, gravel, &c., which are dragged forward underneath the ice, are called ground-moraines, or moraines profondes. See GLACIER, BOULDER-CLAY.