Moraine

A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice sheet.

[7] Passive processes involve the placing of chaotic supraglacial sediments onto the landscape with limited reworking, typically forming hummocky moraines.

[10] Moraine may also form by the accumulation of sand and gravel deposits from glacial streams emanating from the ice margin.

These fan deposits may coalesce to form a long moraine bank marking the ice margin.

Reworking of moraines may lead to the formation of placer deposits of gold as is the case of southernmost Chile.

[citation needed] Lateral moraines are parallel ridges of debris deposited along the sides of a glacier.

[15] Ground moraines are till-covered areas with irregular topography and no ridges, often forming gently rolling hills or plains,[16] with relief of less than 10 meters (33 ft).

[19] Named for Gerard De Geer, who first described them in 1889, these moraines may have developed from crevasses underneath the ice sheet.

They form perpendicular to the lateral moraines that they reside between and are composed of unconsolidated debris deposited by the glacier.

[6][22] In permafrost areas an advancing glacier may push up thick layers of frozen sediments at its front.

As the glacier melts or retreats, the debris is deposited and a ridge down the middle of the valley floor is created.

The Kaskawulsh Glacier in the Kluane National Park, Yukon, has a ridge of medial moraine 1 km wide.