Glaciers Part 2 Flashcards
Define the mass balance gradient
The entire system that includes the accumulation and ablation of ice on a glacier
Define regelation
pressure fluctuations in ice causes ice to melt (obstacle causes high pressure, melting) and then refreeze (obstacle leaves, water refreezes)
Define plucking
Ice moves up over an obstacle, causing a high pressure that melts water. As the water moves past the object, it refreezes, but in the process picks up rocks and sediment and boulders
Define abrasion
The rocks frozen int he glacier move over the substrate, carving grooves in it
Describe competence
a measure of flow strength, as gaged by the size of the
largest particle it can carry.
What are glaciers deposits of sediment, rocks, and gravel called?
till
What is the consistency of till?
Diamictons (poorly sorted, massive mixes of mud, sand and gravel
Define drumlins
streamlined hills generated beneath flowing glacier ice
Define a moraine
Mound of sediment (commonly mix of till and well sorted sand
and gravel), typically generated at the edge (end or sides) of a glacier.
Define eskers
Elongate ridge of sand and gravel generated by meltwater
flowing along base of glacier. Eskers commonly link to large fanshaped
sand and gravel bodies (outwash) generated where the
stream expands and decelerates at ice front.
What evidence exists that Canada was (almost entirely) covered by glacier
ice during the last glaciation?
- Striations
- Landforms
- Till and dispersal trains within
- Isostatic rebound
- Disrupted drainage