Erosion and Deposition by Glaciers 1

What are Glaciers? Glaciers are: any large mass of ice that moves slowly over land 2

How do Glaciers form? Glaciers form: In areas where more snow falls than melts. 3

What are the 2 types of glaciers? Continental Glaciers Continental Glaciers Valley Glaciers Valley Glaciers 4

Continental & Valley Glaciers Large masses of ice Large masses of ice Move slowly on land Move slowly on land Shape the land Shape the land 5

Continental Glaciers Description: a a glacier that covers much of a continentFeature: Continental glaciers can spread out over millions of square kilometers. Location Today: Cover approximately 10% of Earth’s surface mainly in Greenland and Antarctica.Past: Ice Ages – when large parts of Earth were covered with Continental glaciers Ice Ages – when large parts of Earth were covered with Continental glaciers 6

How do Continental Glaciers move? Continental Glaciers: Continental Glaciers: can flow in all directions. They spread out much as pancake batter spreads out in a frying pan. can flow in all directions. They spread out much as pancake batter spreads out in a frying pan. 7

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. 8

How do Valley Glaciers move? Valley Glaciers: Valley Glaciers: move due to the force of gravity. move due to the force of gravity. 9

How do Glaciers Cause Erosion? The two processes by which glaciers erode the land are: The two processes by which glaciers erode the land are: PluckingPlucking AbrasionAbrasion 10

Plucking Plucking is: The process by which a glacier picks up rocks as it flows across the land. 11

Abrasion Abrasion occurs: As a glacier drags the rock over the ground the land is gouged & scratched. As a glacier drags the rock over the ground the land is gouged & scratched. 12

Earth’s Surface Textbook Reference Your Earth’s Surface textbook has a very nice diagram of landforms created by glacial erosion and deposition. Your Earth’s Surface textbook has a very nice diagram of landforms created by glacial erosion and deposition. Please open your textbook to pages as you view the next slides. Please open your textbook to pages as you view the next slides. 13

What Landforms are Created by Glacial Erosion? Horn: Horn: When glaciers carve away the sides of a mountain, the result is a horn or a sharpened peak.When glaciers carve away the sides of a mountain, the result is a horn or a sharpened peak. Cirque: Cirque: A cirque is a bowl-shaped hollow eroded by a glacier.A cirque is a bowl-shaped hollow eroded by a glacier. Fiord: Fiord: A fiord forms when the level of the sea rises filling a valley once cut by a glacier.A fiord forms when the level of the sea rises filling a valley once cut by a glacier. Arête: Arête: An arête is a sharp ridge separating two cirques.An arête is a sharp ridge separating two cirques. U-Shaped Valley: U-Shaped Valley: Slowly moving valley glaciers carve or scoop out a U- shaped valley.Slowly moving valley glaciers carve or scoop out a U- shaped valley. 14

Glacial Deposits Glacial Till: The sediment deposited as a glacier melts and recedes is known as glacial till. The sediment deposited as a glacier melts and recedes is known as glacial till. G lacial till is of various sizes, and can be in the size of clay, silt, sand, gravel, or boulders. G lacial till is of various sizes, and can be in the size of clay, silt, sand, gravel, or boulders. 15

What Landforms are Created by Glacial Deposition? Moraine: 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.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: Drumlin: A drumlin is a long mound of till that is smoothed in the direction of the glaciers flow.A drumlin is a long mound of till that is smoothed in the direction of the glaciers flow. Kettle Lake: Kettle Lake: A kettle lake forms when a depression left in till by melting ice fills with water.A kettle lake forms when a depression left in till by melting ice fills with water. 16

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. 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 Visual Glossary of Glacial Features Visual Glossary of Glacial Features Visual Glossary of Glacial Features 17

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. 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. hsystem/glaciers/ hsystem/glaciers/ 18