❄️glaciation sg3b

Question 1

key facts about laurentide ice sheet (LIS)

Answer 1

• maximum extent 21,000 years ago & covered over 13,000,000 km^2
• reached as far south as 37*N
• as thick as 2-3km

Question 2

how is the ice flow in an ice sheet different to that in a valley glacier

Answer 2

in an ice sheet ice accumulates in centre and then flows outwards and downwards towards margins where it is thinnest (zone of ablation)

Question 3

what is the geology of hudson bay

Answer 3

soft shale sedimentary rocks was able to worn away by LIS

Question 4

what are the 3 types of rock

Answer 4

• shale
• granite
• limestone

Question 5

describe shale

Answer 5

sedimentary rock which is made of layers so the rock can split into thinner pieces

Question 6

describe granite

Answer 6

igneous rock, interlocking grains of minerals that are strongly bound together, some joints

Question 7

describe limestone

Answer 7

remains of organic matter, hard sedimentary rock with lots of joints & bedding planes so water can flow into the rock = lots of FTW

Question 8

how does the latitude influence the formation of landforms

Answer 8

high latitude = less intense sunlight = colder temps = positive mass balance: LIS covered 2/3 of north america and depth reached 2-3km deep in places

Question 9

how did climate influence the formation of landforms

Answer 9

wisconsin ice age = temps were sun zero

Question 10

describe the proglacial lake formed by the LIS

Answer 10

lake missoula
- ice sheet retreated so water was trapped behind ice dam for form lake
- when the pressure of water burst dam = mega flooding which happens 100 times over 7000 years

Question 11

describe toll sheets & moraine formed by the LIS

Answer 11

remember WARS
W adena lobe
A lexander moraine
R ed coloured sediment
S andstone & shale

Question 12

describe the great lakes formed by the LIS

Answer 12

former river valleys that were enlarged & deepened by glacial erosion by ice lobes (tongue shaped glaciers extending from main LIS)

Question 13

describe drumlins formed by LIS

Answer 13

in nyc, 10,000 drumlins covering 12,000 km^2

Question 14

describe hudson bay formed by LIS

Answer 14

an ellipsoidal basin where the LIS was centred as pressure is very high and ice is very thick

Question 15

short term changes due to the LIS

Answer 15

• sudden mega floods - flowed for 10 hours at 80mph = lots of erosion
• rockfall creates subglacial debris
• mass movements on moraines

Question 16

medium term changes due to the LIS

Answer 16

• FTW as needs some temp changes
• retreats & advances so moraine changes position
• growth of proglacial lakes

Question 17

long term changes due to the LIS

Answer 17

• erosion: debris which was deposited eg drumlin field
• ellipsoidal basins grew bigger
• biological weathering when vegetation begins to grow

Question 18

how are different landforms interconnected

Answer 18

subglacial debris which was created due to erosion & weathering eg in hudson bay is deposited in zone of ablation as moraine/drumlins