Glacial Landforms Flashcards
Abrasion
Erosion caused by rocks and boulders in the base of a glacier acting like a giant file scratching and scraping the rocks below
Arete
A sharp, knife-like ridge formed between two corries cutting back by processes of erosion and freeze-thaw.
Bulldozing
Ice pushes material of all shapes and sizes in front of it as it moves slowly forwards.
Corrie/ Cirque
Armchair- shaped hollow in the mountainside formed by glacial erosion, rotational slip and freeze-thaw. This is where the valley glacier begins. When the ice melts, it can leave a small, circular lake called a tarn.
Drumlin
A hill made of glacial till deposited by a moving glacier, usually elongated or oval in shape, with the longer axis parallel to the former direction of ice.
Erratics
Rocks which have been transported and deposited by a glacier some distance from their source region.
Freeze-Thaw Weathering/ Frost- Shattering
It occurs in cold climates when temperatures are often around freezing point and where exposed rocks contain many cracks. Water enters the cracks during the warmer day and freezes during the colder night. As the water turns to ice it expands and exerts pressure on the surrounding rock, causing pieces to break off.
Glacial Trough/ U-Shaped Valley
A river valley deepened and widened by the erosive action of glaciers; it becomes U-shaped rather than the normal V-shape of a river valley.
Hanging valley
A tributary valley to the main glacier, too cold and high up for ice to move easily. It therefore wasn’t eroded as much as the lower main valley, and today is often the site for a waterfall, crashing down onto the main valley floor.
Moraine
Frost-shattered rock debris and material eroded from the valley floor and sides, transported and deposited by the glacier. It is out of the ice.
Outwash
Material, chiefly sand or gravel, deposited by meltwater streams in front of, and underneath, a glacier.The material is sorted and rounded by water action.
Plucking
A type of erosion where meltwater in the glacier freezes onto rocks. As the ice moves forwards, it pulls out large pieces along the rock joints.
Pyramidal Peak
Where several corries cut back to meet at a central point, the mountain takes the form of a steep pyramid.
Ribbon Lake
A long, narrow lake found in glacial valleys formed in locations where the glacier had more ersosive power, eg in areas of softer rock, where the valley gradient temporarily steepened or a tributary glacier joined the main valley.
Rotational Slip
This occurs when the ice moves in a circular motion. This process can help to erode hollows in the landscape, and deepen hollows into bowl shapes.
