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Glacial Aretes

The black lines you can see on the photo are glacial moraine. Moraine is material transported by a glacier and then deposited. There are eight types of moraine, six of which form recognizable landforms, and two of which exist only whilst the glacier exists. The types of moraine that form landforms are Ground, lateral, medial. push, recessional and terminal The two types only associated with glacial ice are subglacial and englagial moraine. 

Ground Moraine. 
Ground moraine is till deposited over the valley floor. It has no obvious features and is to be found where the glacier ice meets the rock underneath the glacier. It may be washed out from under the glacier by meltwater streams, or left in situ when the glacier melts and retreats. 

Lateral Moraine
Lateral moraine forms along the edges of the glacier. Material from the valley walls is broken up by frost shattering and falls onto the ice surface. It is then carried along the sides of the glacier. When the ice melts it forms a ridge of material along the valley side.

Push Moraine
Push moraines are only formed by glaciers that have retreated and then advance again. The existence of a push moraine is usually evidence of the climate becoming poorer after a relatively warm period. Material that had already been deposited is shoved up into a pile as the ice advances, and because most morain material was deposited by falling down not pushing up, there are characteristic differences in the orientation of rocks within a push moraine. A key feature enabling a push moraine to be identified is individual rocks that have been pushed upwards from their original horizontal positions.

Recessional Moraine
Recessional moraines form at the end of the glacier so they are found across the valley, not along it. They form where a retreating glacier remained stationary for sufficient time to produce a mound of material. The process of formation is the same as for a terminal moraine, but they occur where the retreating ice paused rather than at the furthest extent of the ice.

Terminal Moraine
The terminal moraine forms at the snout of the glacier. It marks the furthest extent of the ice, and forms across the valley floor. It resembles a large mound of debris, and is usually the feature that marks the end of unsorted deposits and the start of fluvial sorted material.

Supraglacial Moraine
Supraglacial moraine is material on the surface of the glacier, including lateral and medial moraine, loose rock debris and dust settling out from the atmosphere.

Glacial terms
Firn (Névé) – snow that accumulates to form ice
Nunataks – Exposed summits in Ice sheets
Supraglacial debris -  Eroded material on top of the glacier
Englacial debris -  Eroded material in the middle of the glacier
Subglacial debris -  Eroded material underneath the glacier
Frost Shattering – Freeze thaw material that falls onto the glacier
Abraision (striations) – Erosion of the valley floor by subglacial debris
Plucking – Glacier freezes onto loose rock and plucks it away when it moves
Bergschrund – the Crevasse at the head of the glacier in which melt water collects
Rotational movement – the erosion effect that causes Cirques
Arêtes – formed by 2 adjacent cirques eroding backwards
Pyramidal Peaks – formed by 3 or more adjacent cirques eroding backwards
Glacial Troughs – flat valley floors
Ribbon lakes – in glacial troughs
Truncated Spurs – Ridges cut short by glaciers
Hanging valleys - Valleys cut by glaciers with waterfalls
Roche Moutonnee – Resistant rock smooth one side with plucked crags downstream
Rock Drumlins - Resistant rock smooth both sides – Whalebacks
Till Drumlins – Glacial till and debris in groups broad upstream long and thin down
Terminal Moraines – Glacial debris dumped at the end of a glacial
Lateral Moraines – Glacial debris dumped at the side of a glacial
Medial Moraines – Glacial debris from two lateral moraines when glaciers meet
Kettle Lakes – Depressions caused by large ice lump that then melted
Eskers – lines of subglacial meltwater streams deposited debris