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GCSE Tourism and National Parks

Key Term Notes
Ablation The loss of ice from a glacier due to surface melting, evaporation and the calving of icebergs.
Abrasion The wearing away of rocks by the action of water, ice or wind using moving debris.
Arête A sharp ridge of rock formed by two cirques meeting back to back. A good example is Striding Edge in the Lake District.
Boulder clay / Till Glacial moraine consisting of thick clay with angular rocks. The exact composition will depend on the rocks eroded by the glacier. Boulder clay is sometimes called till.
Cirque, Cwm, Corrie A steep armchair shaped hollow formed by the erosion of the rock by snow and ice. The rotational movement of the ice within the cirque hollows out the base creating a depression. The hollow will become a tarn once the ice retreats.
Crevasse A vertical crack in the glacial ice. It may be formed when a glacier begins to move down a steep slope, when it is forced to make a sharp turn, or when he ice has to move over undulations in the glacier bed. Crevasses can open and close and vary in their size and depth. Most are formed across the glacier but where a glacier widens they may also form parallel to the direction of flow.
Drumlins Elongated oval hills made of Boulder clay. The long axis is parallel to the flow of the original glacier with the steeper end facing towards to flow of the ice. They are a depositional feature.
Erratics Large blocks of rock which were picked up by a glacier then deposited, sometimes hundreds of miles away, from their source when the ice melted.
Hanging valley A hanging valley is a tributary valley that enters the side of a U shaped glaciated valley. Originally the 'hanging' valley would have joined the main valley in a normal way, its streams or rivers flowing into the main valley at the same level. The main valley was glaciated and made deeper, but the side valleys were left at their original level. When the ice melted they were no longer level with the bottom of the valley due to the deepening which had occurred. They appear to 'hang' on the steep sides of the new valley, their streams flowing into the main valley via waterfalls.
Ice sheet Vast areas of ice which can cover much of a continent. A modern example is Antarctica. During Ice Ages these sheets of ice advanced and covered much of Northern Europe, reaching as far south as Bath.
Lip The down slope edge of a cirque base forms a lip. As the ice rotated in the cirque it moved down at the back wall and was forced upwards as the glacier began to move out of the cirque. This creates a lip at the edge due to decreased erosion. See Cirque for further information.
Moraine The rock material eroded by a glacier is known as moraine. There are four main types of moraine which you need to remember.
Moraine - 1 Lateral 1. Lateral Moraine : Moraine which forms along the sides of a glacier.
Moraine - 2 Terminal 2. Terminal Moraine : Moraine which collects along the front of a glacier
Moraine - 3 Ground 3. Ground Moraine : Moraine underneath the glacier.
Moraine - 4 Medial 4. Medial Moraine : A band of moraine along the centre of the glacier formed when two glaciers join, their lateral moraines meeting to form the central band of debris.
Plucking An erosional process. Ice freezes to rocks surrounding the glacier. As the glacier moves the rocks are pulled with the ice to which they are attached. This results in the pieces of rock being tugged, or 'plucked' away from the bed and sides of the valley.
Pyramidal peak A pyramid shaped peak formed when cirques develop all around a mountain. As the cirques erode backwards and meet each other a very sharp and jagged peak is formed.
Roches moutonnée Translated, this means 'sheep rocks' and gives an idea of what they look like. The rocks are smooth on the upstream side and have rough, plucked surfaces on the downstream side. The upstream surface is often marked with striations.
Snout The downstream end of a glacier.
Striations These are scratch marks found on rocks which were eroded by glaciers. When the ice moved over large rocks, the fragments of rock held in the ice were scraped across the surface scratching it. The striations are parallel to the direction of ice movement.
Tarn The lake which forms in the hollow at the base of a cirque
Truncated spur A river spur cut off by glaciation of a former river valley. The spur typically has an abrupt and near vertical end.
U shape valley Glacial valleys have a U shape cross section due to downward erosion across the entire valley floor. By contrast river valleys have a V shape cross section.
Valley glacier A glacier that originates high up a mountain and then flows down a valley. This is the usual type of glacier, also known as an Alpine glacier.

Last Updated on 08/05/01
By KS