Extreme Environments

Question 1

Whats permafrost?

Answer 1

Impermeable permanently frozen ground for at least 2 consecutive years

Question 2

What’s thermokast?

Answer 2

Depressions caused by subsidence due to the melting of permafrost - leads to waterlogged soil

Question 3

What is thermokast caused by? (4)

Answer 3

• change in vegetation affects albedo affect
• shifting of stream channels
• fire which destroys permafrost
• disruption of vegetation

Question 4

What are the 3 different types of permafrost?

Answer 4

• continuous (-5/-50)
• discontinuous (-1.5/-5)
• sporadic (0/1.5)

Question 5

What is plucking?

Answer 5

Occurs at the base of the glacier

Water seeps into joints of rock, freezes onto the rock and is ripped out by the moving glacier

Question 6

What is abrasion?

Answer 6

Debris carried by glacier scratches sides of rocks leaving striations

Question 7

What does the rate of erosion depend on?

Answer 7

• local geology
• the amount of load carried by glacier
• weight and thickness of glacier

Question 8

How do Cirques form?

Answer 8

1) periglacial hollow is enlarged by freeze-thaw
2) Ice accumulates in the hollow
3) After reaching a certain height, ice moves out in a rotational way which erodes rock around it by abrasion and plucking
4) Cirques keeps enlarging due to freeze-thaw and sometimes forms a lake

Question 9

How are arretes and pyramidal peaks formed?

Answer 9

Due to headward recession (cutting back of 2 or more cirques)

Question 10

How are hanging valleys formed?

Answer 10

Formed by tributary glaciers, which are left suspended over

Question 11

What is drift?

Answer 11

Refers to all fluvioglacial and glacial deposits left after ice has melted

Question 12

What is till and what are its two types?

Answer 12

Till refers to deposit that is angular and unsorted
Lodgement till - from a moving glacier
Ablation till - from a stagnant glacier

Question 13

What are the characteristics of till? (5)

Answer 13

• poor sorting/stratification
• mixture of rock type
• many particles of striations
• compaction of deposits
• sub-angular particles

Question 14

What are erratics?

Answer 14

Large boulders that don’t belong with the local geology

Question 15

What is moraine? What are the 3 types of moraine?

Answer 15

Lines of loose rocks, weathered by the valley side and carried by the glacier

• terminal moraine
• lateral moraine
• medial

Question 16

What is medial moraine?

Answer 16

When two glaciers merge and two lateral moraines form in between the enlarged glacier

Question 17

What is froze heave?

Answer 17

When water freezes in soil lifting up individual soil particles to the surface

Question 18

What is solifluction?

Answer 18

Water freezes rocks and soil under. This melts and flows downhill. It doesn’t infiltrate the soil because of the impermeable permafrost. When it’s deposited it forms solifluction lobe.

Question 19

What is frost creep?

Answer 19

Movement of sediments from frost heave, moving downhill due to gravity

Question 20

What is patterned ground?

Answer 20

Patterns in ground such as circles, stripes that are found in soil coming from intense frost action

Question 21

What are pingos?

Answer 21

Isolated, conical hills only found in periglacial areas formed by freezing water under pressure- expansion of permafrost

Question 22

What are the two types of pingos?

Answer 22

Open system pingos

Closed system pingos

Question 23

What is salt crystallisation?

Answer 23

Causes the deposition of rocks by solutions of salt

Question 24

What are the two main types of salt growth?

Answer 24

• areas of temp. change, where sodium sulphate expands creating pressure of joints
• water evaporates and leave salt crystals (salt expands when heated)

Question 25

What is disintegration?

Answer 25

Rock heats up during the day and expands, then contracts at night which causes stress in outer layer- exfoliation occurs

Question 26

What do flash floods do?

Answer 26

Carry sediments which have large erosive force, flowing through canyons which leads to deposition

Question 27

What is an exotic/ exogenous river?

Answer 27

Comes from a wetter environment but flows through a desert

Question 28

What is an endoheic river?

Answer 28

Those that drain inland lake or sea

Question 29

What is an ephemeral river?

Answer 29

Those that flow seasonally or after storms

Question 30

Dunes shape and size depends on what factors? (4)

Answer 30

- supply of sand - direction of wind - nature of the ground surface - presence of vegetation

Question 31

What is deflation?

Answer 31

Progressive removal of small material leaving behind larger materials forming stony deserts

Question 32

What is abrasion (wind)?

Answer 32

Erosion carried out by wind-borne particles (acting like sandpaper) Usually within 1 metre of the ground where the largest, heaviest, most erosive particles are carried