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GLACIERS

GLACIERS. GLACIERS. Just 15,000 years ago, up to 30% of Earth’s land was covered by glacial ice . GLACIERS. During this time period, the earth was just coming out of an ice age. This is simply a period of time when much of earth’s land is covered with ice. GLACIERS.

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GLACIERS

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  1. GLACIERS

  2. GLACIERS • Just 15,000 years ago, up to 30% of Earth’s land was covered by glacial ice.

  3. GLACIERS • During this time period, the earth was just coming out of an ice age. • This is simply a period of time when much of earth’s land is covered with ice.

  4. GLACIERS • Sheets of ice that were thousands of meters thick carved out places like Long Island, Cape Cod and The Great Lakes.

  5. GLACIERS • Today, glaciers still cover about 10% of the earth’s land area. • In these areas they are still sculpting the landscape.

  6. GLACIERS • Glaciers are formed in areas where more snow falls in the winter than melts in the summer. • The snowline is the lowest elevation that remains covered with snow all year.

  7. GLACIERS • At the poles, this is at sea level, but at places near the equator, it is at or near the peaks of mountains. • The more snow that is packed on the top of old layers, the more pressure on those lowest layers. • The lowest layers recrystallize into large ice crystals.

  8. GLACIERS • Gravity pulls glaciers downhill and as they do, they accumulate, transport, and deposit sediment.

  9. GLACIERS • Valley glaciers are one type of glacier. • This is a stream of ice that flows between steep rock walls from a place near the top of the mountain valley. • Basically put, they flow through a river valley.

  10. GLACIERS • Another type of glacier is called an ice sheet. • They flow in all directions from one or more centers and they cover all but the highest land.

  11. GLACIERS • Ice sheets are sometimes called continental ice sheets because of the large amount of land they occupy. • They are gigantic compared to valley glaciers.

  12. GLACIERS • Today, there are two remaining ice sheets in the world today. • Combined, they cover about 10% of Earth’s land area. • One covers about 80%of Greenland. • The other covers Antarctica, in some places 4300 meters thick! • That’s nearly ten Empire State Buildings stacked up!

  13. GLACIERS • The Antarctic Glacier counts for about 80% of the world’s ice, and holds nearly 2/3 of the Earth’s fresh water.

  14. GLACIERS • The movement of glaciers is referred to as glacial flow. There are two types of this… • Plastic Flow • Basal Slip

  15. GLACIERS • Plastic flow is when the entire glacier begins to distort or change shape. • It does this because of the enormous pressure. • This usually begins about 50 meters below the ice surface

  16. GLACIERS • Basal slip is when a glacier simply slides along using its own melt to make it slippery.

  17. GLACIERS • Different glaciers move at different speeds. • Some move so slowly that trees and other vegetation can grow on them! • Some can advance several hundred meters per day! • Some alternate between rapid movement and no movement.

  18. GLACIERS • Glaciers are constantly gaining and losing ice. • The zone of accumulation at the head of a glacier is above the snow line. • The zone of wastage is below the snow line and any ice or snow here is lost to melting.

  19. GLACIERS • The glacial budget is the balance or lack of balance between the accumulation and wastage.

  20. GLACIERS • Glaciers cause glacial erosion as you well know!!! • What are glacial erratics?

  21. GLACIERS • There are many types of glacial erosion. • One type is called plucking. • This is when rock and other sediment is pulled up by glaciers and carried to another place.

  22. GLACIERS • Another type of glacial erosion is called glacial abrasion. • This simply scrapes the land smooth as it slides along…much like sandpaper!

  23. GLACIERS • The rate of glacial erosion is highly variable. • Factors that effect it are… • Rate of Glacial Movement • Thickness of Ice • Shape, Abundance and Hardness of Affected Rock • Type of Surface below Glacier

  24. GLACIERS • Glacial Troughs are the U-shaped valleys created by moving glaciers. • Cirques are bowl-shaped depressions at the head of a glacial valley that is surrounded on three sides by steep rock walls.

  25. GLACIERS • Arêtes are peaks that are made when two cirques are very close creating a sharp ridge. • Horns are when several cirques surround a large mountain.

  26. GLACIERS • A new term we have for glacial erraticsis glacial drift. • There are two types this… • Till • Stratified Drift

  27. GLACIERS • Till is when an object is simply dropped when a glacier melts. • Stratified drift is when a layer is laid down over a long span of land.

  28. GLACIERS • Glaciers are responsible for a large number of depositional features. These include… • Moraines • Outwash Plains • Kettles • Drumlins • Eskers

  29. GLACIERS • Moraines are the layers or ridges of till left by glaciers. • Outwash Plains are sediment ramps that result from an ice sheet.

  30. GLACIERS • Kettles are when blocks of stagnant ice melt leaving a pit filled with water. • Drumlins and Eskers are hills made entirely of till.

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