Erosion and Deposition by Glaciers Created By: Mr. Kreeger

1. Erosion and Deposition by Glaciers Created By: Mr. Kreeger

2. Page References and Homework • Page References • Page 191-205 Chapter 13 • Homework • 1-6 on page 195 • 7-12 on page 199 • 13-18 on page 202 • 19-21on page 205

3. Table of Contents • Glaciers Defined • Formation of Glaciers • Valley or Alpine Glaciers • Continental Glaciers or Ice Sheets • Glacier Movement • Glacial Deposition • Landforms caused by Glacial Deposition • Landscape Features

4. Roughly 18,000 yrs ago 30% of the earth’s surface was covered by glaciers. This period is known as the GREAT ICE AGE

7. Introduction Video Clip Glaciers

8. 1. Glaciers Defined • A large mass of ice, formed on land by the compaction and recrystallization of snow, that is moving downhill or outward under the force of gravity. • Formed when snowfall > than rate of melting

9. 2. Formation of Glaciers • Form when average incoming snowfall> than avg. amount lost by melting and evaporation Snow increases each year • Picture A- Formation • Picture B- Growing • Picture C- Retreating

10. 2. Formation of Glaciers cont.. • As snow increases and evaporation occurs ice crystals become rounded forming granular snow. • As more snow falls (alternating melting and refreezing compacts snow into a layer called firn grows into solid ice.

11. This diagram shows how the elevation of the snowline changes with latitude. The approximate elevation of the snowline is indicated on this diagram by the white line. SNOWLINE 6,000m 5,000m Glaciers Form 4,000m 3,000m 2,000m Glaciers Do NOT Form 1,000m Sea Level North Pole 75N 60N 45N 30N 15N Equator

12. 3. Valley or Alpine Glacier • Gravity pulls downward and outward on bottom layers • This type of glacier carves a U shaped valley. ***Remember streams carve a V shaped valley

13. U-Shaped Valley

15. 4. Continental Glacier or Ice Sheets • These are very old and thick and may cover entire land masses, snow is close to sea level • Moves very slowly because of weight • When it reaches ocean it can break off Icebergs (called Calving) • Greenland- 1.7 million square Km (3 Km thick) • Antarctica- 12.5 million square Km (5 Km thick)

16. Depth of Greenland & Antarctic Ice Sheets

17. Video clip of glacier movement

18. 5. Glacier Movement • Stationary Glacier- When rate of movement = rate of melting • Winter- Glacier moves more (WHY???) • Summer Glacier moves less and appears to move backwards (WHY???)

22. 6. Glacial Deposition • The sediment that is deposited by glaciers is unsorted (Called Glacial till) *Remember that sediment deposited by water is sorted. • If sediment is transported by melt water of glacier than it is deposited the same as a river would deposit (Sorted)Outwash

23. Glacial till - unsorted

24. 7. Landforms caused by Glacial Deposition • Moraines- Unsorted Sediment along the edge of the glacier. • Terminal Moraine-The furthest point of the glacier (Long Island) • Erratic- A large rock that looks misplaced • Drumlins- Long smooth hills of glacial till, points in direction of glacier movement. • Karnes- melt water from top of glacier • Kettles- Circular lakes-Ice breaks off and melts underground • Moraine Dammed lake- When a glacial moraine blocks a river valley, resulting in a long narrow lakes. (Finger lakes)

25. Moraine/Terminal Moraine

26. Erratic

27. Drumlins

28. Outwash Plains

29. Karnes

30. Kettle Lake

31. Moraine Dammed Lake

32. 8. Landscape Features • Cirques- Semi circular shaped bedrock formed as glacier moves back toward mountain. • Arêtes- Steep sided bedrock formed as glacier retreated in opposite direction. • Horns- Where three arêtes meet up

33. Arête Cirque U-Shaped Valley

34. Kettle Lake Drumlins Esker Outwash plain Till Moraine-dammed lake Glacial Stream Terminal Moraine

35. Standard texting rates only (worst cast US$0.20) We have no access to your phone number Capitalization doesn’t matter, but spaces and spelling do TIPS Poll: Which condition causes glaciers to re...

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37. Standard texting rates only (worst cast US$0.20) We have no access to your phone number Capitalization doesn’t matter, but spaces and spelling do TIPS Poll: Which geologic evidence best supports...

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40. Standard texting rates only (worst cast US$0.20) We have no access to your phone number Capitalization doesn’t matter, but spaces and spelling do TIPS Poll: Which is the best evidence that more ...

41. Standard texting rates only (worst cast US$0.20) We have no access to your phone number Capitalization doesn’t matter, but spaces and spelling do TIPS Poll: Unsorted piles of angular sediments w...

42. Standard texting rates only (worst cast US$0.20) We have no access to your phone number Capitalization doesn’t matter, but spaces and spelling do TIPS Poll: What are Precambrian gneiss cobbles a...

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44. Standard texting rates only (worst cast US$0.20) We have no access to your phone number Capitalization doesn’t matter, but spaces and spelling do TIPS Poll: Large igneous boulders have been foun...