18 wind erosion

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Geology 12 Presents  Outline: • Chp 14 • Chp 15 • Chp 16 • Chp 17 • Chp 18 Mass Wasting (Landslides) Running Water Groundwater Glaciers and Glaciation Wind and Deserts Glaciers and Glaciation A: Introduction B: Glacial Erosion and Transport C: Glacial Deposits Glaciers A: Introduction/Glaciers • Glacier: mass of ice composed of compacted snow and recrystallized snow flowing under its own weight under the force of gravity • Move via: plastic deformation below 40m just from the shear weight of ice basal slip: sometimes with the presence of melt water the glacier may slide Glacier Movement Glacier Movement •Copy diagram Crevasse Total surface movement 40m Plastic deformation Basal slip Types of Glaciers Valley/Alpine Glaciers: confined to mountain valleys (yoodle leh) • Flow down hill • Few km wide by 10’s of km long by several 100 m thick • Ex: Alaskan Alpine Glaciers km wide x 120 km long x 400 m thick ice Climate Last million years Climate Last 400,000 years Climate Last 100,000 years Climate Last 2,400 years • Causes of Ice Ages: – Position of continents blocking ocean current flow (Central America formed 1.5 m yrs ago) – Changes in Earth’ rotation and revolution around the Sun (Milankovitch Theory) – Volcanic Eruptions – Meteorite Impact – Sun’s output changes – CO2 Levels vary Milankovitch Theory a) orbit change Milankovitch Theory b) axis tilt Milankovitch Theory c) axis precession • Do WS 17.2 18 Wind Erosion ppt Northern Ice 1979 & 2003 [...]... Calving: process of producing icebergs Icebergs Icebergs B: Glacial Erosion & Transport B: Glacial Erosion & Transport • Weathering: a glacier is a combination of ice and rock (silt,sand, pebbles, boulders) The primary weathering is mechanical; ice/frost wedging (plucking or quarrying)  Handout WS 17.1 NoteHelper Glacial Eroded Landforms • Erosion: glaciers carry the sediment within the ice AND grind/polish
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Xem thêm: 18 wind erosion , 18 wind erosion , 18 wind erosion , Glacial Striations: hard rocks projecting below the ice cut grooves., Cirques: spoon shaped basin at head of glacial valley., Arete: sharp ridge formed by 2 cirques, Horn: pyramid mountain peak formed by 3 or 4 cirques., Hanging Valley/Trough: a tributary valley not as deep as the main valley., Ice Scoured Plain: glacier stripped unconsolidated sediment leaving scoured bedrock with little lakes/swamps and small hills (northern Manitoba & Quebec, NWT)., Till Landforms a) Erratics: large boulder deposited by glacier, Outwash = Stratified Drift *Kettle: block of ice is buried by outwash ( or in a moraine). When it melts a depression is formed., Outwash = Stratified Drift Landforms e) Kame Terrace

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