Option C - Physical processes and landscapes

Question 1

plucking

Answer 1

occurs at the base of the glacier
as the ice moves, the meltwater from the glacial seeps into the joints of the rocks and freezes, which is then ripped out by moving glaciers.

Question 2

abrasion

Answer 2

the debris carried by the glacier scrapes and scratches the rock, leaving striations or grooves in the rock

Question 3

cirques (corries)

Answer 3

an amphitheatre-shaped valley that has been scooped out by erosion at the head of a glacier

Question 4

formation of corries

Answer 4

1. a preglacial hollow is enlarged by nivation (freeze-thaw and removal by snowmelt)
2. ice accumulates in the hollow
3. eventually the weight of the ice causes it to move downhill, erodes the floor by plucking and abrasion
4. meltwater trickles down the bergschrund (a crevasse that forms when the moving glacier ice separates from the non-moving ice above)

Question 5

pyramidal peaks

Answer 5

formed where three or more corries and arêtes meet. The glaciers have carved away at the top of a mountain, creating a sharply pointed summit.

Question 6

aretes

Answer 6

a narrow ridge of rock which separates two valleys; form when two cirques erode headwards towards one another

Question 7

glacial troughs (U-shaped valley)

Answer 7

are formed by the process of glaciation in mountainous areas - have a characteristic U shape, with steep, straight sides and a flat bottom.

Question 8

hanging valley

Answer 8

formed by tributary glaciers, which do not cut down to the level of the main valley but are left suspended above

Question 9

roche moutonee (sheepback)

Answer 9

a bare mound of rock that can vary in size from a few meters to hundreds of metres high

Question 10

formation of roche moutonee (sheepback)

Answer 10

smoothed and polished on their up-valley side by abrasion but plucked on their down-valley side as ice accelerates

Question 11

moraines + example

Answer 11

any glacially formed accumulation of unconsolidated glacial debris (soil and rock)
Kettle Moraine, Wisconsin, USA

Question 12

characteristics of moraines

Answer 12

the dirt and rocks composing moraines can range in size from powdery silt to large rocks and boulders
at the snout of the glacier is a crescent-shaped mound or ridge

Question 13

drumlins + example

Answer 13

small oval mounds up to 1.5 km long and 100m high of glacial debris streamlined into elongated hills
Clew Bay, County Mayo, Ireland

Question 14

erratics + example

Answer 14

stones and rocks that were transported by a glacier, and left behind when the glacier melted
range in size
Madison Boulder, New Hampshire, USA

Question 15

freeze-thaw

Answer 15

occurs when temperatures fluctuate above and below freezing point
water expands by 9-10% when it freezes
this places pressure on rocks which may be broken to fragments

Question 16

solifluction

Answer 16

gradual movement of wet soil and other materials downslope
upper layer of the soil melt in summer, however the lower layers remain frozen
the upper layers slide over the lower layers

Question 17

frost creep

Answer 17

a type of solifluction that occurs because of frost heaving and thawing

Question 18

process of frost creep

Answer 18

ground surface freezes, elevating particles at right angles to the slope
the particles rise up and because cold temperatures cause water inbetween particles to freeze and expand
ice thaws in the warm season turning back to water, the contracting surface drops the particles in elevation
the drop is caused by gravity so the particles move downslope

Question 19

thermokarst

Answer 19

a landscape of hummocks and wet hollows resulting from subsidence caused by the melting of permafrost

Question 20

process of thermokarst

Answer 20

solifluction and other types of weathering removes the active layer and other vegetation which leaves behind the ice wedge exposed to the surface
the surface melts due to the sun, climate change, fire etc

Question 21

pingo

Answer 21

an isolated, conical hill up to 90m high and 800 wide, which can only develop in periglacial areas

Question 22

formation of pingos

Answer 22

result of movement and freezing of water under pressure
forms from water under-pressure
open system: the source of water is distant
closed system: where the source of water is local

Question 23

patterned ground + example

Answer 23

array of stone stripes, polygons and garlands that may be found in periglacial areas
Kerid crater, Iceland

Question 24

formation of patterned ground

Answer 24

frost heave
cracking of the surface due to drying
cracking of the surface due to drying, heaving or thermal contraction
mass displacement

Question 25

permafrost

Answer 25

permanently frozen ground

Question 26

types of permafrost

Answer 26

continuous
discontinuous
sporadic

Question 27

continuous permafrost

Answer 27

-5 to -50 degrees

Question 28

discontinous permafrost

Answer 28

-1.5 to -5

Question 29

sporadic permafrost

Answer 29

0 to -1.5

Question 30

active layer

Answer 30

the layer above the permafrost which is highly mobile and seasonally thaws out

Question 31

weathering

Answer 31

the breakdown of materials of the Earth’s crust into smaller pieces (sediment)

Question 32

why is wind erosion more pronounced in arid environnmets?

Answer 32

lack of vegetation and moisture
sand and sediments blown along the surface
wind lifts sand up

Question 33

salt crystallisation

Answer 33

In areas where temperatures fluctuate around 26-28 degrees, sodium sulphate and sodium carbonate expand by about 300 per cent.
This creates pressure on joints, forcing them to crack.
Water evaporates and salt crytals are left behind.
When temperatures increase the salts expand and exert pressure on rocks.

Question 34

disintegration

Answer 34

In deserts, day time temperatures can exceed 40 degrees whereas night temperatures are just a little above freezing.
Rocks heat up by day and contract by night.
Since rocks are poor conductor of heat, stresses only exist in the outer layers. Repetition of this process causes rocks to become brittle and causes rocks to break down.

Question 35

types of rivers

Answer 35

exotic/exogenous river
endorheic river
ephemeral river

Question 36

exotic/exogenous river

Answer 36

those that have their source in another wetter environment and then flow through a desert

Question 37

endorheic river

Answer 37

those that drain into an inland lake or sea

Question 38

ephemeral river

Answer 38

flow seasonally or after storms and often have high discharges and high sediment levels

Question 39

sand dunes

Answer 39

a mound of sand formed by the wind

Question 40

formation of sand dunes

Answer 40

wind blows sand into a sheltered area behind an obstacle. Dunes grow as grains of sand accumulate.

Question 41

yardangs

Answer 41

wind-eroded landforms where the softer rock strata are removed, leaving the more resistant layers to form long ridges

Question 42

formation of yardangs

Answer 42

form in alternate bands of hard and soft rock
weaker rock is less resistant and erode more quickly, whereas stronger rock is eroded more slowly
the stronger rock is left as ridges

Question 43

zeugens

Answer 43

wind-eroded landforms where the softer rock strata are removed, leaving the more resistant layers to form mushroom-like features

Question 44

formation of zeugens

Answer 44

most erosion within the first meter of the ground as wind lifts material
less resistant rock worn away quickly
more resistant rock worn away slowly

Question 45

mesas

Answer 45

plateau-like features with steep sides that represent the remnant of a former extensive layer of resistant rock

Question 46

buttes

Answer 46

smaller versions of mesas that represent the final stage of development of erosion before the resistant rock is finally eroded

Question 47

wadis

Answer 47

river channels that vary in size and are generally steep sided and flat bottomed

Question 48

formation of wadis

Answer 48

formed by flash floods or during wetter pluvial periods

Question 49

characteristics of glacial deposits

Answer 49

poor sorting – till contains a large range of grain sizes, for example boulders, pebbles, clay
poor stratification – no regular sorting by size
a mixture of rock types – from a variety of sources
striated and subangular particles
long axis orientated in the direction of glacier flow
some compaction of deposits.