Fluvioglacial landforms Flashcards
What does fluvioglacial mean?
•Landforms created by meltwater
•Erodes and deposits meltwater
•Assists basal sliding in warm based glaciers
•Increased as the glacier retreats
What is a glacial moulin?
A hole in a glacier created by meltwater, which the meltwater then disappears down
Meltwater importance
•Transports moraine sub glacially, allowing erosion to take place
•Reduces sub glacial friction increasing basal sliding
•Supra-glacial meltwater helps enlarge nivation of hollows
•Erodes channel
•Forms rivers
•Can re freeze, binding the base of the glacier to the bed rock
Glacial deposits
Unstratified (no layers), unsorted, angular material of various shapes and sizes - Physical weathering and erosion
Fluvioglacial deposits
Stratified (Layers), sorted, smooth and rounded material
What is a sandur/outwash plain?
-Located at the snout of the glacier
-Created by erosional and depositional processes
-Meltwater streams deposits gravel, sand and clay throughout the summer
-Can freeze over winter, causing freeze-thaw weathering
-Larger material is deposited close to the glacier
-Hydrostatic pressure is lost outside of the glacier, causing material to be deposited
What is a braided stream?
-Seasonal melt variants causes fluctuations in sediment load
-Excess sediment deposited during low discharge obstruct flow
-The channel braids as it looks for a more efficient way
What is an esker?
-Formed by subglacial flow
-Long ridge of sediment running in the direction of flow
-Made of sorted sand and gravel
What is a kame?
-A hill or hummock composed of stratified sand and gravel laid down by the glacial melt water
-Deposited along the front of a slowly melting or stationery glacier
-Will collapse when the ice retreats
What is kame terrace?
-Sorted sand and gravel forming along the sides of a glacier
-Deposited by meltwater streams flowing along the sides of a glacier
-Warm rock melts the ice close by forming a long depression which a meltwater stream can flow
What are kettle holes?
-Dead ice is left on an outwash plain by a retreating glacier
-Meltwater streams bury blocks of ice under sediment deposits
-Ice melts and leaves a depression in the outwash plain
What is a proglacial lake?
-A lake develops immediately in front of the glacier
-Dammed by a terminal moraine
-Sediment is deposited on a lake bed
What are glacial lakes and varves?
-Lakes on the fringes of the ice are filled with layered deposits
-A top layer of silt lying on top of a layer of sand deposited over a year
-Used to show past climates and temperatures
-Finer silts deposits in winter and heavier deposits form in spring
