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8.3 Glaciers

A lpine. 8.3 Glaciers. Small glaciers that form valleys. Types of glaciers. Ice sheets. Enormous glaciers that can cover entire continents. Describe the steps. Firn :. Thick, dense compacted snow. Glacier Formation. Glacial ice:. Firn compacts into glacial ice. Advancing:.

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8.3 Glaciers

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  1. Alpine 8.3 Glaciers Small glaciers that form valleys Types of glaciers Ice sheets Enormous glaciers that can cover entire continents

  2. Describe the steps Firn: Thick, dense compacted snow Glacier Formation Glacial ice: Firn compacts into glacial ice Advancing: A glacier growing faster than it is melting Retreating: A glacier melting (receding) at the leading edge faster than its growing. It’s NOT traveling backwards.

  3. Plastic Flow Glacier Movements Describe: Deep within, there is a huge amount of pressure due to weight of ice pressing down. 50 meters thick of ice creates enough pressure to cause ice to flow through the center of a glacier very slowly.

  4. Basal Slip Glacier Movements Water beneath glacier acts as a lubricant, so entire glacier can slide. This movement can cause a large crevasse (crack), to form. Describe: Rate of movement: Typically a few meters/ day, but can have faster surges.

  5. Striation Long scratch marks found in rocks due abrasion caused by rocks & gravel dragged by glacial movement. Describe: Glacial structures from erosion U-Shaped Valleys Describe: V-shaped valleys that are widened by glaciers.

  6. Horn peaks Describe: When several cirques converge, the part that is not cut out looks like a horn sticking out of the ground. Glacial structures from erosion Cirques Describe: Valleys that look like giant armchairs because they have 3 steep sides & one open side.

  7. Fjords Describe: Very steep inlets to the ocean. Glacial structures from erosion Roche moutonnees Landforms w/ 1 rough side & 1 side that has been abraded smooth. Describe:

  8. Describe: The coarsely graded sediment deposited by glaciers Glacial Drift Till Describe: Unsorted glacial sediment

  9. Glacial Erratics Describe: Big rocks deposited by a glacier into an area w/ a different type of rock. Structures Formed Morraines Describe: Piles of boulders, rocks, pebbles, & clay left behind by a glacier.

  10. Terminal Moraines Describe: form at the edge of glaciers. Structures Formed Drumlins Smooth, egg-shaped hills left behind by continental ice sheets. Describe:

  11. Define: Deposits left by melted water coming off a glacier. Structures Formed: kettles Describe: When large blocks of ice get trapped under stratified drift, the ice melts and leaves large holes. Stratified Drift Eskers Describe: Winding ridges of sand & gravel left behind by receding glaciers.

  12. Earth’s Orbit Effects: Change in Earth’s orbit around the sun cause slight temperature variations. Precession Effects: The tilt of Earth’s axis changes over time & can affect the amount of sunlight reaching different parts of earth.

  13. Current ice age theory Explain: Changes in the Earth’s axis of rotation can work together to alter the temperatures. This is thought to lead to the formation of large glaciers & put Earth into ice ages. Last ice age 2 million years ago, & peaked 20,000 years ago.

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