Erosion%20and%20Deposition%20by%20Glaciers

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Erosion and Deposition by Glaciers
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What are Glaciers?

• Glaciers are
• any large mass of ice that moves slowly over land

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How do Glaciers form?

• Glaciers form
• In areas where more snow falls than melts.

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What are the 2 types of glaciers?

• Continental Glaciers
• Valley Glaciers

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Continental Valley Glaciers

• Large masses of ice
• Move slowly on land
• Shape the land

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Continental Glaciers

• Description
• a glacier that covers much of a continent
• Feature
• Continental glaciers can spread out over
  millions of square kilometers.
• Location Today
• Cover approximately 10 of Earths surface
  mainly in Greenland and Antarctica.
• Past
• Ice Ages when large parts of Earth were
  covered with Continental glaciers

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How do Continental Glaciers move?

• Continental Glaciers
• can flow in all directions. They spread out
  much as pancake batter spreads out in a frying
  pan.

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Valley Glaciers

• Description
• a long narrow glacier that forms when snow and
  ice builds up in a mountain valley.
• Feature
• Although much smaller than continental glaciers,
  valley glaciers can be tens of kilometers long.
• Location Today
• High up in many mountain ranges worldwide.
• Past
• U-shape valleys show where Valley glaciers once
  slid down from a mountain.

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How do Valley Glaciers move?

• Valley Glaciers
• move due to the force of gravity.

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How do Glaciers Cause Erosion?

• The two processes by which glaciers erode the
  land are
• Plucking
• Abrasion

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Plucking

• Plucking is
• The process by which a glacier picks up rocks
  as it flows across the land.

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Abrasion

• Abrasion occurs
• As a glacier drags the rock over the ground the
  land is gouged scratched.

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Earths Surface Textbook Reference

• Your Earths Surface textbook has a very nice
  diagram of landforms created by glacial erosion
  and deposition.
• Please open your textbook to pages 84-85 as you
  view the next slides.

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What Landforms are Created by Glacial Erosion?

• Horn
• When glaciers carve away the sides of a mountain,
  the result is a horn or a sharpened peak.
• Cirque
• A cirque is a bowl-shaped hollow eroded by a
  glacier.
• Fiord
• A fiord forms when the level of the sea rises
  filling a valley once cut by a glacier.
• Arête
• An arête is a sharp ridge separating two cirques.
• U-Shaped Valley
• Slowly moving valley glaciers carve or scoop out
  a U-shaped valley.

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Glacial Deposits

• Glacial Till
• The sediment deposited as a glacier melts and
  recedes is known as glacial till.
• Glacial till is of various sizes, and can be in
  the size of clay, silt, sand, gravel, or boulders.

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What Landforms are Created by Glacial Deposition?

• Moraine
• A moraine forms at the edge of a glacier where
  the glacier deposits till. Moraines are usually
  in the form of a mound or ridge.
• Drumlin
• A drumlin is a long mound of till that is
  smoothed in the direction of the glaciers flow.
• Kettle Lake
• A kettle lake forms when a depression left in
  till by melting ice fills with water.

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Glacier Picture Gallery

• Please open the link below and go through the
  slides showing many of the landforms created by
  glacial erosion and deposition discussed in this
  power point.
• Visual Glossary of Glacial Features

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Brain Pop on Glaciers and Ice Ages

• If you would like to watch a cute video presented
  by Brain Pop to learn more about Glaciers and Ice
  Ages, click on the link below.
• http//www.brainpop.com/science/earthsystem/glacie
  rs/