Glacial Ice Flashcards
What are crevasses?
Deep, wedge-shaped openings in a moving mass of ice called a glacier
Crevasses usually form in the top 50 meters (160 feet) of a glacier.
What are ogives?
Arcuate, convex, down-glacier-pointing bands or undulations on the surface of a glacier at the base of an icefall
Two types of ogives: Wave ogives (varying height) and Band ogives (alternating light- and dark-colored bands).
What are ice falls?
Very steep parts of a glacier that resemble frozen waterfalls, characterized by deep crevasses and rapid flow
Caused in part by gravity.
Define ice shelves.
Large platforms of glacial ice floating on the ocean, fed by one or multiple tributary glaciers
Ice shelves act as a brake on the flow of glaciers, slowing their movement toward the sea.
How do ice shelves gain mass?
From ice flowing into them from glaciers on land, snow accumulation, and freezing of marine ice to their undersides
Ice shelves are floating tongues of ice extending from glaciers grounded on land.
What processes lead to ice shelf mass loss?
Calving icebergs, basal melting, sublimation, and wind drift
Basal melting occurs towards the outer margins of ice shelves.
What is calving?
The process when chunks of ice break off from ice shelves, glaciers, and icebergs
It occurs due to cracking, melting from below, or hydrostatic pressure.
What does calving cause in relation to glaciers?
A loss of buttressing, allowing the glacier behind the shelf to accelerate its movement towards the ocean.
What is the Marine Ice Sheet Instability hypothesis?
Describes the instability of a marine ice sheet grounded below sea level on land sloping downward from the coast
Example: West Antarctic Ice Sheet.
Define the grounding line.
The boundary between the ice sheet on land and the floating ice shelves
The position and migration of this line control the stability of a marine ice sheet.
What is ice shelf buttressing?
The role that ice shelves play in supporting and stabilizing the flow of inland glaciers
A loss of buttressing allows glaciers to accelerate, increasing ice discharge into the ocean.
