1. 1. Contents Glaciers Glacial Theory Important terms regarding Glaciers Anatomy of Glaciers Glacier Budget Types of Glaciers Erosional work of Glaciers Depositional work of Glaciers References
2. 2. Glaciers A thick ice mass that originates on land from the accumulation, compaction, & recrystallization of snow. Agents of erosion acquire, transport and deposit sediment Occupy ~10% of land area Interrupts hydrologic cycle by locking up water Gravity and Slope are primary force of motion Entire ice sheet moves 5 to 50 m/yr Fastest movement within the center Friction Slows down the sides
3. 3. Glacial Theory 1. 1829 - Swiss engineer named J. Venetz first proposed that glaciers had once been more extensive than at present. His observations inspired Jean de Charpentier to begin a field study of active glaciers. 2. 1837 - de Charpentier presented his results to the Swiss naturalist, Louis Agassiz (considered to be the "Father of Glaciation"), who developed the first comprehensive theory of Glaciation.
4. 4. Important Terms Regarding Glaciers Ablation zone: The area of a glacier where mass is lost through melting or evaporation at a greater rate than snow and ice accumulate. Accumulation zone: The area of a glacier where mass is increased through snowfall at a greater rate than snow and ice is lost through ablation. Basal sliding: The sliding of a glacier over the ground on a layer of water. Firn: The granular ice formed by the recrystallization of snow; also known as Nv. Glacial surge: The rapid forward movement of a glacier. Snow line: The elevation above which snow can form and remain all year. Terminus: The leading edge of a glacier; also known as the glacier snout. Till: A random mixture of finely crushed rock, sand, pebbles, and boulders deposited by a glacier.
5. 5. Glacial Trough: Glacier flown constantly widens its rock channel, when the ice is finally swept away because of melting a deep steeped walled feature appears which is known as Glacial Trough Fiord: When floor of a trough open to the sea lies below the level sea level, the water enters as the ice front retreats making a deep narrow Estuary know as Fiord Glaciation: The period during which the continental ice sheet grows and spread outward over vast areas is known as Glaciation Shelves: Presences of great plates of floating Glaciers is known as Shelves
6. 6. Anatomy of Glaciers
7. 7. Distribution of Glaciers in the World (World Glacier Monitoring service, 1989) Regions Area (km2) Africa 10 Antarctica 13593310 Asia and Eastern Europe 185211 Australia ( New Zealand) 860 Europe ( western) 53967 Greenland 1726400 North America ( excluding Greenland) 276100 South America 25908 Total 15861766
8. 8. Velocities of different Types of Glaciers (Glaciers 2nd , p#92. by Michael Hambrey & Jurg Allean) Glacier Regions Centre line velocity (Meters /year) Comments Lambert glacier East Antarctica 347 Part of largest glacier drainage system in Antarctica. Amery ice shelf East Antarctica 1200 As above Jakobshavn Isbrae NW Greenland 4700 (max 8360) Fastest outlet glacier from Greenland Ice sheet Columbia glacier Alaska 1500 Accelerated recording of tide water glacier. Fastest in the world Grosser Swiss Alps 200 Fastest part of largest glacier in the Alps
9. 9. Firn It is ice that is at an intermediate stage b/w snow & glacial ice. Firn has the appearance of wet sugar.
10. 10. Glacier Budget In - Zone of accumulation Snow accumulates and forms ice Outer limit is the snowline Out Zone of wastage ablation general term for loss of ice or snow from a glacier 1. Sublimation 2. Melting 3. Evaporation
11. 11. Glacier Budget
12. 12. Types of Glacier 1. Valley (Alpine) Found in mountainous areas Smaller than ice sheets Lengths greater than widths Only cover a small region Transform V-shaped valleys into U -shaped valleys
13. 13. Alpine Glacier
14. 14. Types of Glacier 2. Ice sheets (Continental Glacier) Large scale cover 10% of Earths land Found in polar regions Greenland 1.7 million km2 Antarctica 1.4 million km2
15. 15. Continental Glaciers
16. 16. Erosional work of Glaciers Plucking loosen and lift blocks of rock Abrasion sediment in ice acts as giant sandpaper Abrasion polish surface of rock smooth. This geomorphic feature is known as Glacial Polish. Glacial melt water can have a light, cloudy appearance, and is called Glacial Milk. Creates Rock flour very fine-grained material Creates Striations grooves scratched in bedrock that indicate direction of ice movement
17. 17. Plucking and Abrasion
18. 18. Erosional Work of Glaciers Cirque Arte Col Horn Crevasse Striations Glacial Polish Cirque Glacier Tarn Lakes
19. 19. Cirque Artes Erosional Landforms
20. 20. Cirque Artes A scooped-out, amphitheater shaped basin at the head of an alpine glacier. A sharp saw tooth or serrated ridge that divides two cirque basins. Knife-edge in French
21. 21. Arte A sharp-edged ridge of rock formed b/w adjacent cirque glaciers.
22. 22. Col A saddle-like narrow depression formed by two head ward eroding cirques that reduce an Arte.
23. 23. Horn / Saddle A pyramidal, sharp-pointed peak that results when several cirques glaciers gorge an individual mountain summit from all sides.
24. 24. Glacial Horn A high mountain peak forms when the walls of three or more glacial cirques intersect
25. 25. Crevasse A deep, nearly vertical crack that develops in the upper portion of glacier ice.
26. 26. Striations Striations appear as scratches of various size on rock surfaces.
27. 27. Glacial polish Abrasion polish surface of rock smooth.
28. 28. Cirque Glacier A bowl-shaped depression carved out of a mountain by an alpine glacier.
29. 29. Tarn Lake A small lake that fills the central depression in a cirque.
30. 30. U-shape valley Horn
31. 31. Fjords Cirque Lakes
32. 32. Depositional work of Glaciers Sediments deposited by Glacial melted water that are sorted by size Stratified Drift. The technical term used to describe material deposited by the ice is called Till or Moraine. Till is a heterogeneous combination of un-stratified sediments ranging in size from large boulders to minute particles of clay When till is deposited along the edge of a glacier it tends to form irregular hills and mounds known as Moraines.
33. 33. Depositional Work of Glaciers Terminal Moraine Medial Moraine Lateral Moraine Recessional Moraines Erratic Esker Kame Drumlins
34. 34. Types of Moraines Terminal Moraine is a deposit that mark, the farthest advance of a glacier. Recessional Moraines Moraine deposits created during halts in the retreat of the glacier. Lateral Moraine The debris that falls from valley side slopes can be concentrated in a narrow belt and cause a deposit. Medial Moraine When two glaciers flow together, two lateral moraines can merge to form an interior belt of debris.
35. 35. Erratic A large boulder that a glacier deposits on a surface made of different rock.
36. 36. Esker A long, snakelike ridge of sediment deposited by a stream that ran under or within a glacier.
37. 37. A steep-sided, conical mound or hill formed of glacial drift that is created when sediment is washed into a depression on the top surface of a glacier and then deposited on the ground below when the glacier melts away. Kame
38. 38. Drumlins Drumlins are the hill shaped deposits of till, come in a variety of dimensions. Lengths can range from 100-5000meters & heights can sometimes exceed 200 meters.
39. 39. References http://nsidc.org/glaciers/questions/what.html http://www4.uwsp.edu/geo/faculty/lemke/geol370/lecture_notes/09_glacial_erosion_landfor ms.html http://www.uvm.edu/whale/GlaciersWhatAre.html http://geography.about.com/od/geographyintern/a/glaciers.htm http://www.cliffsnotes.com/study_guide/Types-of-Glaciers.topicArticleId-9605,articleId- 9518.html http://www.angelfire.com/alt/bfeldman_geology115/Geology-pg3.htm http://www.physicalgeography.net/fundamentals/10af.html http://www.geography-site.co.uk/pages/physical/glaciers/deposit.html http://www.scienceclarified.com/landforms/Faults-to-Mountains/Glacial-Landforms-and- Features.html#b