Characteristics of ice movement - Compressional and extensional ice flow Flashcards

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1
Q

What are glacial crevasses?

A

A crevasse is a deep fissure in a glacier.

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2
Q

Why do glacial crevasses develop?

A

Glacial crevasses develop in response to the variable speed of glacier flow.

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3
Q

What is extensional ice flow?

A

Extensional ice flow is a glacier flow associated with an increase in velocity in a downglacier direction.

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4
Q

When does extensional flow occur?

A

Extensional flow occurs where surface glacier velocity is increasing downglacier and is responsible for the development of transverse crevasses.

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5
Q

What is compressional flow?

A

Compressional flow is glacier flow associated with a decrease of velocity in a downglacier direction.

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6
Q

When does compressional flow occur?

A

Compressional flow occurs where there is a decrease of velocity in a downglacier direction: some old transverse crevasses may close up.

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7
Q

Why do marginal crevasses develop?

A

Marginal crevasses develop at the valley sides due to the drag exerted on the ice.

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8
Q

Where do longitudinal crevasses develop?

A

Longitudinal crevasses develop where a valley widens out.

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9
Q

Where do radial crevasses develop?

A

Radial crevasses develop where the snout of the glacier spreads out.

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