1. Aim: How do glaciers move? 12-04-09 Topic: Glaciers DN: 1.How does wind move sand? 2.Why are rocks eroded by wind more eroded at the base of the rock than at the top?

2. Webquest: Glaciers http://www.uky.edu/AS/Geology/howell/go odies/elearning/module13swf.swfhttp://www.uky.edu/AS/Geology/howell/go odies/elearning/module13swf.swf

3. What is a glacier?

4. Is there a difference between the snow on top of a mound of snow and the snow on the bottom? What causes the difference?

5. GLACIER: A LARGE MASS OF ICE ON LAND THAT FLOWS UNDER THE PRESSURE OF ITS OWN WEIGHT – DOWNHILL OR OUTWARD DUE TO GRAVITY

6. What are the two kinds of glaciers? A valley (alpine) glaciers: long, slow-moving, streams of ice found in mountain areas (high elevation) occupying former river valleys. Continental glacier: very old (1000’s of years), thick (1000’s of meters) mass of ice covering almost.an entire land mass.  GREENLAND: 1.7 Million SQ MI, 3 KM thick  ANTARCTIC: 12.5 Million SQ MI, 5 KM thick

7. VALLEY CONTINENTAL

8. CONTINENTAL ICE SHEETS  GREENLAND: 1.7 Million SQ MI, 3 KM thick  ANTARCTIC: 12.5 Million SQ MI, 5 KM thick

9. Lets look at what happens to glaciers Iceland melting (3:47 min) http://www.nationalgeographic.com/

10. Lets see how glaciers form and erode the land in this BrainPOP animated movie! http://glencoe.mcgraw- hill.com/sites/0078778026/student_view0/ brainpop_movies.html#http://glencoe.mcgraw- hill.com/sites/0078778026/student_view0/ brainpop_movies.html# Click “Glaciers”

11. For glaciers to form, there must be a year-round thick mass of snow which becomes compacted to form ice. Abundant snowfall and cool summers help this process.

12. WHERE DO THEY FORM? AREAS OF HIGH LATITUDE OR HIGH ELEVATION WHERE THEY HAVE COLD SUMMERS PRESENTLY OCCUPY 10% OF WORLD’S TOTAL LAND AREA (COMPARED TO 32% DURING THE PLEISTOCENE EOCH)

13. At which location would a glacier NOT form? 1.15° N. latitude at an elevation of 4,000 m. 2.30° N. latitude at an elevation of 3,000 m. 3.45° N. latitude at an elevation of 1,000 m. 4.0° latitude at an elevation of 6,000 m.

15. Process of Glacier Formation 1. SNOWFLAKES ACCUMULATE 2. SNOWFLAKES COMPACT 3. FIRST INTO FIRN (LIKE PACKED SNOWBALLS) 4. LOWER LAYERS TURN INTO GLACIAL ICE (SOLID ICE – NO AIR) UNDER THE WEIGHT OF OVERLYING FIRN AND SNOW

16. Snow becomes glacial ice

17. Glacier de la Girose, Parc des Ecrins, France SNOW FIRN ICE Glacier de la Girose, Parc des Ecrins, France SNOW FIRN ICE

18. HOW DO THEY FORM? MORE SNOW MUST FALL THAN MELTS ZONE OF ACCUMULATION – UPPER PART OF GLACIER ZONE OF MELTING (ABLATION) – LOWER PART SNOW LINE (EQUILIBRIUM LINE) LINE WHERE SNOW IS ALL YEAR LONG

20. HOW DO GLACIERS MOVE? UNDER THE INFLUENCE OF GRAVITY THEIR OWN WEIGHT THE DRIVING FORCE UNDER PRESSURE THE DEEPER ICE BEHAVES LIKE A THICK FLUID (CALLED PLASTIC FLOW) AND FLOWS DOWNHILL OR SPREADS OUT IN ALL DIRECTIONS (when glacier is about 300 ft. thick)

21. GLACIER MOVEMENT GLACIER ADVANCES SNOWFALL > MELTING GLACIER RETREATS SNOWFALL < MELTING STATIONARY GLACIER SNOWFALL = MELTING DYNAMIC EQUILIBRIUM

22. Hundreds of Glaciers Melting Faster in Antarctica

23. GLACIER MOVEMENT GLACIER ADVANCES SNOWFALL > MELTING GLACIER RETREATS SNOWFALL < MELTING STATIONARY GLACIER SNOWFALL = MELTING DYNAMIC EQUILIBRIUM

24. Glacier Erosion Glaciers—master carvers of landscapes.

25. ICE WITHIN GLACIER IS ALWAYS MOVING FORWARD EVEN IF THE GLACIER IS RETREATING OR STATIONARY MANY DEPOSITIONAL FEATURES ARE FORMED ARE FORMED AS A RESULT

28. GLACIER FLOW SPEED IS LIKE A STREAM – FASTER IN THE MIDDLE / LESS FRICTION fastest movement after heavy winters, steep slopes, and in summer CREVASSES form along steep slopes because upper zone of glacier is rigid (rarely go deeper than 120ft. )

29. FASTEST

30. A CREVASSE- Evidence of movement

31. Vocabulary 1.Glacier 2.Valley glacier 3.Continental glacier 4.Cirque 5.Moraine 1.Outwash plain 2.Drumlin 3.Esker 4.Kame 5.Kettle