1. Glaciers UNIT 5 STANDARDS: STATE OBJECTIVES: NCES 2.1.1, 2.1.3, 2.1.4 LESSON 6

2. Lesson Objectives  In this lesson, you will learn about:  How glaciers form  Conditions that form valley glaciers  Conditions that form continental glaciers  How glaciers modify the landscape

3. How Glaciers work  Three things glaciers have:  Mass  Pressure  Gravity  Glaciers shape the land by eroding, transporting, and depositing large volumes of rock and sediment.

4. What is a glacier  Definition  Video Video  Large moving mass of Ice  Form near the earth’s poles  Glaciers have had dramatic effects on human populations: Ice Ages  Cold temperatures keep snow from melting and allow for the accumulation of snow.  Each layers adds more pressure on the layer below, until it turns to ice.

5. What about a Valley Glacier  Characteristics  Form in high mountain valleys  Movement because mass becomes too great to stay in one place …gravity is driving force  Deep cracks in the glacier are crevasses  Speed of glacier determined by slope of valley  Sides of glacier move slower than the middle because of friction with bedrock.

6. Continental Glaciers  Characteristics  Columbia Glacier Columbia Glacier  Form over large areas  Thickest in the center  Form immense ice sheets  Characteristic of Ice Ages, where whole continents were covered

7. Glacial Erosion  Ranking  Plucking  Grind Away  Greatest erosion force on planet  Breaking off and picking up rocks  Constant pressure erodes bedrock by abrasion  Formation of “U-shaped’ valleys

8. Glacial Deposition Landscape  Glacial Till  Moraine  Outwash  Drumlin  Esker  Deposited mixture of the debris carried by glaciers  The ridges left behind by the till, along sides  Debris left when the glacier melts and recedes  The elongated land formed when glaciers travel over moraines  The stream that flows at the base of the glacier, as the ice melts.

9. Lesson Review  Explain how valley and continental glaciers form  How can a valley glacier modify the mountain where it forms  What evidence of past glaciers are present on the earth today  Remember email answers for lesson