13. Periglacial Processes

Question 1

describe the process of nivation (4)

Answer 1

1) nivation is the first process in forming corries
2) snow accumulates in north- and east- facing hollows in the northern hemisphere
3) freeze-thaw and chemical weathering break up the rock below
4) summer meltwater flushes out the debris

Question 2

name some periglacial areas

Answer 2

tundra: northern Russia, Alaska and northern Canada

alpine: Alps

Question 3

what are the types of periglacial environment?

Answer 3

arctic continental
arctic maritime
alpine

Question 4

why is Russia pro-global warming?

Answer 4

Russia would become the breadbasket of the world

as permafrost would thaw into productive farmland

Question 5

which process is prevalent in periglacial areas?

Answer 5

frost action due to the permafrost

Question 6

what percentage of the land on earth is periglacial?

Answer 6

25%

Question 7

how much precipitation do deserts receive each year?

Answer 7

less than 150mm

Question 8

annual average temperature of periglacial regions

Answer 8

between -15°C and -1°C (this includes night time/seasons and so there are still fluctuations above and below 0°C)

Question 9

average annual rainfall (excluding snowfall) in periglacial areas

Answer 9

between 120 and 1400mm (excluding snowfall)

Question 10

summer temperatures can reach up to ___ in periglacial environments

Answer 10

15°C

Question 11

winter temperatures can reach below ___ in periglacial environments

Answer 11

-50°C (normally remain below 0°C throughout winter)

Question 12

what is the ground beneath the permafrost like?

Answer 12

talik

pockets of unfrozen ground due to higher temperatures

Question 13

what latitude is the North Pole?

Answer 13

90° N

Question 14

what latitude is the South Pole?

Answer 14

90° S

Question 15

what latitude is the UK?

Answer 15

approximately 55° N

Question 16

name a city with the same latitude as Liverpool

Answer 16

Edmonton, Canada

Question 17

depth of the active layer vs. permafrost

Answer 17

as little as a few cm of active layer at ~70° N (permafrost can be 400m deep

active layer can be 1.5m at ~60° N (rare little islands of permafrost; discontinuous)

Question 18

factors which influence the depth of permafrost

Answer 18

bodies of water (specific heat capacity = takes longer to heat = mild climates = protected land/talik around them)

vegetation insulates the ground

mountain ranges (higher altitude = colder = albedo effect = colder)

Question 19

mass movement processes

Answer 19

frost creep
rock falls
solifluction/gelifluction

Question 20

frost creep

Answer 20

REQUIRES A SLOPE AND FLUCTUATING TEMPERATURES
produces terracettes

frost heave (= expands by 9%) as the active layer freezes causes the active layer to expand up at 90° to the slope
when the active layer thaws, material drops down at 90° to the ground due to gravity

this process repeats as material zig-zags down the slope
(similar to longshore drift)

active layer is waterlogged as meltwater cannot percolate the permafrost

Question 21

effect of freeze thaw weathering on vegetation

Answer 21

freeze-thaw weathering forms a scree slope/blockfield if sloped/flat ground

blockfields are flat fields of rock which vegetation cannot colonise, meaning soils can’t form

Question 22

what does solifluction form?

Answer 22

solifluction lobes/tongues

Question 23

what is another word for solifluction?

Answer 23

gelifluction

Question 24

effect of vegetation on solifluction

Answer 24

soil is formed by pioneer species

vegetation also makes freeze-thaw weathering more likely

Question 25

describe the process of solifluction

Answer 25

temperatures rise and melt the huge volume of water frozen in the upper permafrost impermeable permafrost so meltwater cannot percolate and little evaporation occurs excessive lubrication reduces friction between soil particles so it slides downslope if as little as 2° inclination