GLACIERS

Question 1

• Glaciers

Answer 1

a permanent mass of ice that flows downslope under the influence of gravity

Question 2

o During last ice age:

Answer 2

 30%
 Land covered
 10% water was ice
 Sea level dropped 100m
 If all glacial ice melted, sea level would rise about 60m

Question 3

• Summarize the factors and causes of ice ages and describe the age and extent of the last ice age

Answer 3

o 90,000-20,000 bp
o 25,000 years ago the flow from interior and glacier flow down strait of Georgia moving towards van and surrey

Question 4

causes of ice age

Answer 4

 Perturbation of earth’s orbit
* Milankovitch cycles: change the amount of heat from solar radiation that any particular part f earth receives
 Greenhouse effect
* Increases CO2 in the atmosphere causes retention of heat, decreased Co2 decreases retention of heat
 Plate tectonics
* Volcanoes
* Rates of plate movement
* Positions of continents (Albedo)
* Effect on ocean circulation

Question 5

o How glacier form

Answer 5

 Accumulation of snow in winter > melting of snow in the summer
 Compaction of accumulated snow  ice
 Ice must flow (down slope) under the influence of gravity

Question 6

• Discuss the concepts governing the flow of glaciers

Answer 6

o Continental
 Flow from thickest to thinnest
o Alpine
 Flow down slope
o How glacier move
 Ex: alpine glacier confined to a valley
* Above bedrock there is a zone of plastic flow, followed by a rigid zone
* In the rigid zone ice locks and moves together
* In the upper plastic the grains move slightly farther than the lower grain
* Lower plastic moves less distance than upper grain

Question 7

o Positive feedback loops

Answer 7

 Albedo is the ratio of reflected solar radiation ot the toal incoming solar radiation
* Sea ice melt, exposes darker ocean surface  reflectivity, or albedo is altered (ocean reflects less sunlight)  ocean absorbs more heat  temp rises

Question 8

o Snowball earth

Answer 8

 Hypothesis that the earth has been completely frozen in past, most recently ~650 Ma
 Earth cools  more ice  earth cools

Question 9

o Alpine glacier

Answer 9

 Confined to mountains
 Originate in mountains- high altitude

Question 10

o Continental glacier

Answer 10

 Ice sheets
 Cover vast areas of land, polar regions

Question 11

ice sheets

Answer 11

o Greenland icesheet
 Blankets 81% of Greenland
 1,756,000km2
o Antarctic ice sheet
 Covers 90% of Antarctica
 14.2 million km2
 Contains 92% of all glacial ice on the planet

Question 12

o Abrasional features:

Answer 12

cirque, arete, horn, tarn lake, u shaped valley, hanging valley, fjord, glacial polish, striation, rock flour

Question 13

o Depositional features

Answer 13

 Drift- till, outwash, moraines, kettle, esker, drumlin, erratic

Question 14

 Features of deposition

Answer 14

• Moraines (end, lateral, medial, ground)
• Till carried/ pushed along by glacier deposited at the edges of the glacier
• Kettle- small hole in the till where a piece of ice was while sediment was ebign deposited
• Usually filled with water
• Esjer- positive relief feature made from sedimentation in drainage channels at the base of the glacier
• Drumlin- wedge like mound of till showing ice movement direction (towards the milder slope)
• Erratic large exotic rock carried long distances from their orgin by the ice- dropped once the ice melt away

Question 15

o Features of abrasion

Answer 15

 Tarn
* A lake sitting within a crique once the ice has melted
 Glacial polish
 Striation, grooves
 Rock flour

Question 16

o Deposits

Answer 16

 Glacial drift- general term for all sediment derived from glaciers
 Till- poorly sored, unstratified, hummocky
 Outwash- sorted and stratified

Question 17

horn

Answer 17

• Pointy part of mountain
• When several cirque glacier gouge a mountain from multiple sides a horn results

Question 18

arete

Answer 18

• slim walkway
• when glacier erode parallel valley, a thin, sharp ridge forms between them

Question 19

cirque

Answer 19

• Pooling of snow like mudslide

Question 20

 Bergschrund

Answer 20

• Above the “mudslide”

Question 21

o Tarns

Answer 21

 Small mountain lakes which from in cirques

Question 22

o Hanging valleys/ waterfalls

Answer 22

 Produce when smaller glacier, feeding into larger recede
 Are where smaller glacier merge into a large one

Question 23

o Features of abrasion U-shaped valley

Answer 23

 Formed by large glaciers slowly grinding out the valley

Question 24

o Fjord

Answer 24

 When a glacial trough meets the ocean, he glacier can continue to erode elow sea level
 When the glacier retreats, the through floods and forms a deep fjord