Landscapes of Glacial erosion: Flashcards
What are all the landforms in this section?
corries, arêtes, glacial troughs, hanging valleys, truncated spurs, roches moutonnées.
What is a Corrie and the characteristics of a Corrie and how does a Corrie form?
Corries form when snow continues to build
up in a depression or nivation hollow,
eventually compacting to form a glacier. The
glacier becomes trapped within the hollow,
meaning the only way it can move is through
rotational slip. The back wall is eroded
through plucking and frost shattering, and the
hollow is deepened through rotational
abrasion. Water can fill corries to make tarns.
Last a long period of time.
Example: Red Tarn, The Lake District.
Everything about an Arête?
A knife-edged ridge formed between two
corries (when the two steep back walls
meet).
Last a long time.
Example: Striding Edge, Lake District.
Pyramidal Peak?
When 3 corries erode back-to-back-to-back. Creates isolated peak.
E.g Matterhorn in Switzerland.
Glacial Troughs?
U-shaped valley caused by a glacier bulldozing and eroding through a v-shaped valley. Erodes away a river’s interlocking spurs. Which leaves smooth but steep truncated spurs on the valley sides and a wide, flat valley floor. Misfit streams or Ribbon lakes continue to flow.
Last for a Long time.
Example: Glen Geusachan, The Cairngorms
Hanging Valleys?
A smaller u-shaped valley caused by a
tributary glacier. The smaller glacier does not have enough energy to erode to the valley floor, leaving a hanging valley.
Waterfalls often form here.
Last for a long time.
Example: Fiordland National Park, New Zealand.
Truncated Spurs?
Within a typical river valley, interlocking spurs of rock will jut out into the valley. When the valley is occupied by ice, the glacier truncates (cuts off), the tips of the rocky spurs as it moves downhill. Leaving behind steep cliffs.
Abrasion is a dominant process in the formation of truncated spurs, plucking and frost action takes place on bare rocky surfaces.
Roche Moutonnées?
Definition = Outcrops of rock on the valley floor that have been sculpted by the moving ice.
Upstream side - pressure melting occurs, which facilitates basal sliding and the process of abrasion as the glacier slides over the rock outcrop. Smooth polished striations.
Downstream side - reduction in pressure causes the meltwater to freeze between the rocky outcrop and the glacier, as glacier moves forward plucks away loose rocks leaving a jagged surface.
