1.   Glacier: thick mass of ice, forms over land  Compaction and recrystallization of snow  Glacier Types: Glacier Types:  Valley (alpine) glaciers – mountainous areas  Ice sheets (continental) glaciers Ice sheets  Over Greenland and Antarctica  Ice caps – cover uplands and plateaus  Piedmont glaciers – cover broad lowlands  Found at steep mountain bases  Movements of glacial ice: Movements  Plastic flow  Basal sliding (slipping along the ground) 1 7: Glaciers Figure 6.2: Present day continental sheets

2.   Glaciers erode by: Plucking -lifting of rock  Abrasion : Rock flour-pulverized rock  Striations -bedrock grooves  Landforms by glacial erosion:  Glacial trough – u-shaped  Hanging valley – valleys above main trough  Cirque – area of snow accumulation  Arête – sharp-edged ridges  Horn – sharp, pyramid-like peaks  Fjord – deep, steep-sided inlets of the sea 2 Glacial Movement Figure 6.10: Erosional landforms created by Alpine glaciers. Glaciers, (9:54) Trollfjord in Norway by Grant, CC-A-SA 2.0

3.   Moraines – layers or ridges of glacial till  Types: lateral, medial, end, ground  Outwash plain or valley train  Kettles  Drumlins  Eskers  Kames 3 Glacial Deposits Figure 6.18: Glacial depositional features. Drumlin in Upstate NY Kettle Lakes

4.   Volcano under Grimasvotn lakes erupts  Near river Skeioara which floods  Land flooded Skaftafell NP  Melts 3 cubic km of ice; peak flow 6000 cubic m/sec  Jokulhalup flow occurs, flow rate 50,000 cubic m/sec  Flood caries ice floes many tons in weight  Icebergs 100-200 tons damages road and striking bridge  Considered a 13 ft high, 660 yd wide tsunami  Flood carries 185 million tons of silt  Outbursts: 1954, 1960, 1965, 1972, 1976  1982, 1983, 1986, 1991, 1996 Case: Vatnajokull Glacier, Iceland 1996 Vatnajokull glacier, Iceland