OCR A Level GL - 11 OCR A Level GL 2.2b MINNESOTA ICE SHEET CASE STUDY 2

Question 1

Where is Minnesota?

Answer 1

It is a midwestern U.S. state bordering Canada and Lake Superior, the largest of the Great Lakes

Question 2

What has primarily shaped the landscape of Minnesota?

Answer 2

Glacial activity throughout the Quaternary period (last 2 million years)

Question 3

What is the name of the ice sheet that shaped the landscape of Minnesota?

Answer 3

Laurentide

Question 4

What is the underlying geology of the northern part of Minnesota?

Answer 4

ancient Archaen granites and gneisses

Question 5

How has the underlying geology of the northern part of Minnesota contributed to the topography of the landscape?

Answer 5

the folding of these rocks has made a more mountainous (hilly) landscape

Question 6

What is the name of the highest point in the state of Minneosota?

Answer 6

Eagle Mountain

Question 7

What is the height of the highest point in Minnesota?

Answer 7

701m

Question 8

What is the underlying geology of the southwestern portion of Minnesota?

Answer 8

thick layer of sedimentary rock

Question 9

How thick was the ice sheet over most parts of Minnesota?

Answer 9

1 km

Question 10

What is the name of the large scale erosional feature found in northern Minnesota?

Answer 10

ellipsoidal basin

Question 11

What are the named features that are evidence of the ellipsoidal basin in northern Minnesota?

Answer 11

Upper and Lower Red lakes

Question 12

What are the unnamed features that are evidence of the ellipsoidal basin in northern Minnesota?

Answer 12

thousands of lakes studding the landscape

Question 13

What evidence is there of the overwhelming erosional impact of the ice sheet on the Minnesota landscape?

Answer 13

There are no high mountains in the state. The highest peaks are only between 500-700m.

Question 14

What small scale evidence of the erosional impact of the ice sheet is there on Minnesota?

Answer 14

striations found on bare rock throughout the state, indicating the direction of ice advance

Question 15

Which part of Minnesota was not covered by the ice sheet and how is this shown in the landscape?

Answer 15

The south east of Minnesota. There are steeper hills and deeper valleys found here as a result of the action of rivers

Question 16

What is a summary of the erosional impact of the Laurentide ice sheet on Minnesota?

Answer 16

The impact has been very considerable and shaped the overall landscape. However, it has not produced spectacular landforms associated with valley glaciers.​

Question 17

What are the names of the 4 main lobes that extended from the Laurentide ice sheet that spread across different parts of Minnesota?

Answer 17

1. Wadena 2. Rainy 3. Superior 4. Des Moines

Question 18

Which part of Minnesota did the Wadena lobe travel over in Minnesota?

Answer 18

It advanced from NE Canada, covering the northwest part of Minnesota and reaching just south of Minneapolis

Question 19

Approximately when did the Wadena lobe retreat, leaving depositional features across the landscape?

Answer 19

~30,000 years ago

Question 20

What are the characteristics of the Wadena lobe till?

Answer 20

red and sandy

Question 21

What are the named moraines that have formed from the Wadena lobe?

Answer 21

1. Itasca 2. Alexandria

Question 22

Where are drumlin fields found from the Wadena lobe?

Answer 22

1. Otter Tail 2. Wadena and Todd counties

Question 23

Which part of Minnesota did the Rainy and Superior lobes travel over in Minnesota?

Answer 23

It advanced from Canada to cover the North East part of Minnesota.

Question 24

Approximately when did the Rainy and Superior lobes retreat, leaving depositional features across the landscape?

Answer 24

~20,500 years ago

Question 25

What are the characteristics of the Rainy and Superior lobe till?

Answer 25

coarse-textured till containing fragments of basalts, gabbro, granite, red sandstone, slate and greenstone.

Question 26

Where can the Rainy and Superior lobe deposits be found in Minnesota?

Answer 26

across the north-eastern half of Minnesota as far south as Minneapolis & St Paul​

Question 27

Approximately when did the Des Moines lobe retreat, leaving depositional features across the landscape?

Answer 27

~13,000 years ago

Question 28

Which part of Minnesota did the Des Moines lobe travel over in Minnesota?

Answer 28

It advanced from North and South Dakota to spread over the south west part of Minnesota

Question 29

What are the characteristics of the Des Moines lobe deposits?

Answer 29

tan to buff coloured and clay-rich due to the shale & limestone at its source in the NE

Question 30

How thick are the Des Moines deposits

Answer 30

over 160m

Question 31

What is a named example of the terminal moraine features formed by the Des Moines lobe?

Answer 31

Prairie Coteau

Question 32

What is the name of the proglacial lake formed by the Laurentide ice sheet

Answer 32

Agassiz

Question 33

When did Lake Agassiz form?

Answer 33

~12,000 years ago

Question 34

What is the name of the moraine dam in Minnesota that was finally overtopped by Lake Agassiz?

Answer 34

Big Stone Moraine

Question 35

What was the name of the glacial river that was formed from the overtopped moraine dam?

Answer 35

River Warren

Question 36

What is the name of present day river valley that now occupies the glacial river Warren valley?

Answer 36

Minnesota river valley

Question 37

How wide the Minnesota river valley in places?

Answer 37

5miles

Question 38

What is the name of the valley where lake Agassiz overtopped the moraine dam?

Answer 38

Brown’s valley

Question 39

What is the name of the land between Brown’s valley and the Minnesota river valley?

Answer 39

Traverse Gap

Question 40

What impact did the glacial River Warren have on how the present day Red River Valley is used?

Answer 40

It left behind fertile silt deposits that make it ideal for agriculture