18 wind erosion

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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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Mục lục

  • Geology 12 Presents

  • PowerPoint Presentation

  • Glaciers and Glaciation

  • Glaciers

  • A: Introduction/Glaciers

  • Glacier Movement

  • Slide 7

  • Slide 8

  • Slide 9

  • Types of Glaciers

  • 1. Valley/Alpine Glaciers

  • Slide 12

  • Ice Sheets: Continental Glaciers

  • Slide 14

  • Ice Sheets: Ice Caps

  • Isostasy

  • Slide 17

  • Glacial Movement

  • Firn

  • Slide 20

  • Slide 21

  • Slide 22

  • Slide 23

  • Slide 24

  • Icebergs

  • Slide 26

  • B: Glacial Erosion & Transport

  • Slide 28

  • Slide 29

  • Slide 30

  • Slide 31

  • 1. Glacial Polish: smooth (shines in reflected light) bedrock.

  • 2. Glacial Striations: hard rocks projecting below the ice cut grooves.

  • 2. Glacial Grooves

  • 2. Big Grooves = Finger Lakes

  • 3. Roche Mountinee: (sheep rock)

  • 3. Roche Mountinee

  • 4. Crag and Tail

  • Slide 39

  • Crag and Tail

  • 5. Cirques: spoon shaped basin at head of glacial valley.

  • 5. Cirques

  • 5. Cirque Lake = Tarn

  • Slide 44

  • 6. Arete: sharp ridge formed by 2 cirques

  • 6. Arete

  • 6. Aretes

  • 7. Horn: pyramid mountain peak formed by 3 or 4 cirques.

  • 7. Horn

  • Slide 50

  • Slide 51

  • Slide 52

  • Slide 53

  • 8. U-Shaped Valley

  • 8. Fjords = Submerged U-Shaped Valley

  • Slide 56

  • 9. Hanging Valley/Trough: a tributary valley not as deep as the main valley.

  • 9. Hanging Valley/Trough

  • 9. Hanging Valley/ Trough

  • Slide 60

  • Slide 61

  • Slide 62

  • 10. Ice Scoured Plain: glacier stripped unconsolidated sediment leaving scoured bedrock with little lakes/swamps and small hills (northern Manitoba & Quebec, NWT).

  • 10. Ice Scoured Plain

  • C: Glacial Deposits:

  • 1. Till Landforms a) Erratics: large boulder deposited by glacier

  • b) Ground Moraine/Subglacial Moraine: material pushed under and compacted under the glacier.

  • c) Lateral Moraine: material pushed to the side of the glacier

  • d) Medial Moraine: result of two glaciers moraines coming together with their lateral moraines.

  • e) End Moraine: form beyond the ice front 2 types

  • e) End Moraine: form beyond the ice front 2 types

  • i) Terminal End Moraine: marks glacier’s farthest advance.

  • Slide 73

  • ii) Recessional End Moraine: smaller end moraines behind the terminal moraine that form as the glacier recedes

  • 1. Till Landforms f) Drumlins: canoe-shaped hill of till formed as glacier over-runs a moraine forming it into a swarm of drumlins. More common with ice sheets.

  • Slide 76

  • 2. Outwash = Stratified Drift Landforms a) Varves: mud deposits in lakes < 1cm thick

  • 2. Outwash = Stratified Drift Landforms a) a) Varves: mud deposits in lakes < 1cm thick

  • b) Outwash Plain: blanket of sediments deposited by melting glacier waters

  • 2. Outwash = Stratified Drift *Kettle: block of ice is buried by outwash ( or in a moraine). When it melts a depression is formed.

  • *Kettle: block of ice is buried by outwash ( or in a moraine). When it melts a depression is formed.

  • Slide 82

  • c) Kames: conical hill (up to 50 m high)

  • Slide 84

  • Slide 85

  • d) Eskers: long winding ridge.

  • Slide 87

  • Slide 88

  • Slide 89

  • Slide 90

  • Slide 91

  • Slide 92

  • e) Kame Terrace

  • 2. Outwash = Stratified Drift Landforms e) Kame Terrace

  • Slide 95

  • Slide 96

  • Slide 97

  • Slide 98

  • Slide 99

  • Causes of Ice Ages

  • Slide 101

  • Slide 102

  • Slide 103

  • Slide 104

  • Slide 105

  • Slide 106

  • Milankovitch Theory a) orbit change

  • Milankovitch Theory b) axis tilt

  • Milankovitch Theory c) axis precession

  • Slide 110

  • Slide 111

  • Slide 112

  • Slide 113

  • Slide 114

  • Slide 115

  • Slide 116

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