Glaciated Landscapes SG3b

Question 1

During what ice age did the Laurentide Ice Sheet exist?

Answer 1

The Pleistocene

Question 2

Where was the Laurentide Ice Sheet centred?

Answer 2

What is now Hudson Bay

Question 3

Were the four names given to the glaciations of the LIS?

Answer 3

Nebraskan, Kansan, Illinois, Wisconsin

Question 4

What was the last glacial period in North America called?

Answer 4

Wisconsin Ice Stage

Question 5

When was the LIS at its maximum extent?

Answer 5

21,000 years ago

Question 6

At its maximum extent, what area did the LIS cover?

Answer 6

13,000,000km2

Question 7

At its maximum extent, how far south did the LIS reach?

Answer 7

37 degrees N

Question 8

How thick was the LIS?

Answer 8

2-3km

Question 9

What were the four ice domes that made up the LIS?

Answer 9

Greenland Ice Sheet, Cordilleran Ice Sheet, Keewatin Sector, Labrador Sector

Question 10

Where was the Labrador Sector centred?

Answer 10

Over Hudson Bay

Question 11

Define Ice Dome

Answer 11

Where accumulation started and flowed outwards, Thickest bit of ice

Question 12

How did the LIS impact mountains?

Answer 12

Massive erosional impact wore down many of the mountains

Question 13

How high are the highest peaks now?

Answer 13

500m - 700m

Question 14

What is the highest natural point in Minnesota with an elevation of 701m?

Answer 14

Eagle Point

Question 15

Define Ellipsoidal Basin

Answer 15

Huge lake basins created by erosion where the ice sheet gouged out deep depressions in the bedrock

Question 16

What is the largest ellipsoidal basin created by the LIS?

Answer 16

Hudson Bay

Question 17

What is the area covered by Hudson Bay today?

Answer 17

1,230,000km2

Question 18

What are the five Great Lakes?

Answer 18

Huron, Ontario, Michigan, Erie, Superior

Question 19

What were the Great Lakes formed by?

Answer 19

The advancing and retreating of ice lobes produced smaller ellipsoidal basins

Question 20

Define Ice Lobes

Answer 20

Tongue shaped glaciers extending from the margins of the main LIS

Question 21

What dammed the Great Lake basins?

Answer 21

Rock bars made from harder rock which wasn’t eroded, Deposited glacial till

Question 22

What was the geology of the Great Lakes area?

Answer 22

Mainly sedimentary (e.g. limestones, shales and sandstone) with some outcrops of resistant igneous rock (e.g. Canadian Shield an area of granite and gneiss)

Question 23

Where is an example of striations?

Answer 23

The shore of Lake Superior

Question 24

How do striations form?

Answer 24

Subglacial debris scratches the bedrock as the LIS moved over it

Question 25

Define Mega Scale Lineations (MSL)

Answer 25

Valley like features formed due to erosion and scouring of the bedrock as a result of ice streams within LIS

Question 26

How long can MSLs be?

Answer 26

100s of km

Question 27

How deep can MSLs be?

Answer 27

100s of m

Question 28

How wide can MSLs be?

Answer 28

100s of m

Question 29

What are the four ice lobes of the LIS which deposited material as till sheets and moraines?

Answer 29

Wadena, Rainy, Superior, Des Moines

Question 30

Where did the Wadena Lobe advance from?

Answer 30

The North

Question 31

What till did the Wadena Lobe deposit?

Answer 31

Red and sandy till derived from the red sandstone and shales to the North and North East

Question 32

Where did the Rainy and Superior Lobes advance from?

Answer 32

The North East

Question 33

What till did the Rainy and Superior Lobes deposit?

Answer 33

Coarse textured till of basalts, gabbro, granite, iron formation, red sandstones, slate and greenstone strewn across the north-eastern half of Minnesota

Question 34

Where did the Des Moines Lobe advance from?

Answer 34

The North West

Question 35

What till did the Des Moines Lobe deposit?

Answer 35

Fine-textured till coloured buff to tan and is clay rich and calcareous due to shale and limestone rocks at its source

Question 36

How many drumlins are in the New York swarm?

Answer 36

10,000

Question 37

What are the erratics in south-western Minnesota?

Answer 37

Three Maidens

Question 38

What is the composition of the Three Maidens and the country rock of where they were deposited?

Answer 38

Three Maidens = Pink and grey granite | Country Rock = Sioux quartzite

Question 39

Define Proglacial Lake

Answer 39

A body of water impounded in front of a glacier/ice sheet

Question 40

What is an example of a proglacial lake?

Answer 40

Lake Missoula

Question 41

Why did Lake Missoula form?

Answer 41

500 cubic miles of meltwater was trapped behind a wall of ice

Question 42

How many mega-floods did the Lake Missoula cause?

Answer 42

100 floods over 2,000 years