Moraine

Originally a French term, moraine is any accumulation of glacially-caused and deposited debris, mostly taking the form of sediments and soil, yet particle sizes from boulders to silt-like glacial flour can be found too. This debris is also unconsolidated, or loose. As it is caused and left behind by glaciers, moraine is useful in determining the history of glacial activity in the area even if the glaciers themselves have long receded and disappeared.

Several types of moraine exist, classified by their dimensions, method of formation and where they lay in relation to the glacier. The glacier may cause debris to drop from pre-existing stone, grind it from the rock it flows over beneath or cause formation on its upper surface. Some examples include:

Lateral moraine forms at the edges of a glacier where cold and abrasion causes its valley walls to loosen and drop material. The glacier then crushes and grinds some of this.

Medial moraine is found in the unusual event of two glaciers merging together into a whole. The lateral moraine on the inner edge of the meeting becomes located at the centre of the new glacier. A line of this running down the centre of a valley tells of this occurring.

Englacial moraine is unique in that it can only be called englacial while its glacier still exists. It is any debris that has fallen onto the glacier's surface and become embedded within. This includes material that has fallen into cracks and crevasses.

Push or Terminal moraine appears as a ridge at the nose of a glacier, being comprised of material pushed up in front of the glacier as it advances. When a glacier retreats or becomes stationary, the moraine is left behind and so is useful in deciding the extent a glacier once had.