Revvase

revvase

What is a crevasse in geography?

A crevasse is a deep crack, crevice or fissure found in an ice sheet or glacier, or earth. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pieces above a plastic substrate have different rates of movement.

What are transverse crevasses and how do they form?

Transverse crevasses are the most common crevasse type. They form in a zone of longitudinal extension where the principal stresses are parallel to the direction of glacier flow, creating extensional tensile stress.

How do Longitudinal crevasses form?

Longitudinal crevasses form parallel to flow where the glacier width is expanding. They develop in areas of tensile stress, such as where a valley widens or bends. They are typically concave down and form an angle greater than 45° with the margin.

What are the characteristics of a crevass?

Crevasses usually have vertical walls and are up to 150 feet deep and as wide as 70 feet. Crevasses, however, are usually narrow and thin, forming extreme hazards for mountaineers crossing a glacier. Crevasses have three distinct forms.

How are crevasses formed in glaciers?

Crevasses usually form in the top 50 meters (160 feet) of a glacier, where the ice is brittle. Below that, a glacier is less brittle and can slide over uneven surfaces without cracking.

What causes a crevasse in the ground?

Crevasses can also be caused by the ice flowing over bumps or steps in the bedrock. By descending into a crevasse, scientists can observe the layers of snow from past years or, deeper down, the ice crystals of the glacier. Crevasses can be small, but many are quite large.

What is a longitudinal crevasse?

longitudinal crevasse. noun. : a crevasse roughly parallel to the direction of ice movement that forms where a glacier spreads laterally.

What are transverse crevasses and how do they form?

Transverse crevasses are the most common crevasse type. They form in a zone of longitudinal extension where the principal stresses are parallel to the direction of glacier flow, creating extensional tensile stress.

What is a crevass?

Crevasses are like windows into a glacier. Form at the beginning of the glacier where the glacier pulls away from the rock wall at its head. Form in the direction of a glacier flow, and where ice slowly spreads out sideways to cover a larger area.

How are crevasses formed in glaciers?

Form near the side. Marginal crevasses are caused by shear between the valley wall and the glacier. They form a herring- bone pattern, pointing about 45° up-glacier from the valley wall. Form across a glacier in a region where the speed is increasing, which causes stretching (tensile stress) in the direction of glacier flow.

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