What are crevasses and where do they form?
a. Crevasses are cracks that form in the zone of fracture on either side of the glacier. They form when tension is created as a result of the glacier moving along irregularly shaped valley walls.
b. Crevasses are cracks that form in the zone of fracture within the middle of the glacier. They form when tension is created as a result of the glacier moving downslope too quickly.
c. Crevasses are cracks formed on the very bottom of a glacier as it moves downslope. They form from melting of ice in places as a result of frictional heat between the glacier and the ground.
d. Crevasses are cracks that form in the zone of fracture at the bottom of the glacier. They form when tension is created as a result of the glacier moving over irregular terrain.
e. Crevasses are cracks that form in the zone of fracture at the top of the glacier. They form when tension is created as a result of the glacier moving over irregular terrain.
The correct answer and explanation is:
The correct answer is:
e. Crevasses are cracks that form in the zone of fracture at the top of the glacier. They form when tension is created as a result of the glacier moving over irregular terrain.
Explanation:
Crevasses are deep, open cracks in a glacier’s surface ice, typically forming in the uppermost 50 meters of the glacier where the ice behaves in a brittle manner. This upper section is called the zone of fracture. Beneath this zone, the ice behaves plastically due to the immense pressure, which prevents deeper fractures from forming.
Crevasses form when the glacier moves over uneven terrain, encountering obstacles like bedrock ridges, changes in slope, or bends in the valley. As the glacier flows, stress is applied unevenly across its surface, leading to tension cracks that propagate downward.
There are several types of crevasses, including:
- Longitudinal Crevasses – These develop parallel to the glacier’s flow, often due to lateral stretching when a glacier spreads out.
- Transverse Crevasses – These form perpendicular to the glacier’s movement, commonly when the glacier speeds up over a steeper slope.
- Marginal Crevasses – Found along the edges of the glacier, they form due to friction with valley walls causing differential ice movement.
- Bergschrund – A type of crevasse that forms where a glacier separates from the ice or snow above it on a mountain.
Crevasses pose significant hazards to mountaineers and explorers, as they can be concealed by snow bridges. Studying them is crucial in understanding glacier dynamics and climate change, as their formation and changes can indicate variations in ice flow and melting rates.
Now, I will generate an image of a glacier with visible crevasses.
Here is the generated image of a glacier with deep, visible crevasses at its surface. It depicts the cracks forming due to tension as the glacier moves over irregular terrain in a mountainous region. Let me know if you need any modifications or further explanations!
