Characteristics of ice movement - Compressional and extensional ice flow Flashcards
What are glacial crevasses?
A crevasse is a deep fissure in a glacier.
Why do glacial crevasses develop?
Glacial crevasses develop in response to the variable speed of glacier flow.
What is extensional ice flow?
Extensional ice flow is a glacier flow associated with an increase in velocity in a downglacier direction.
When does extensional flow occur?
Extensional flow occurs where surface glacier velocity is increasing downglacier and is responsible for the development of transverse crevasses.
What is compressional flow?
Compressional flow is glacier flow associated with a decrease of velocity in a downglacier direction.
When does compressional flow occur?
Compressional flow occurs where there is a decrease of velocity in a downglacier direction: some old transverse crevasses may close up.
Why do marginal crevasses develop?
Marginal crevasses develop at the valley sides due to the drag exerted on the ice.
Where do longitudinal crevasses develop?
Longitudinal crevasses develop where a valley widens out.
Where do radial crevasses develop?
Radial crevasses develop where the snout of the glacier spreads out.
