Option C - Physical processes and landscapes Flashcards Preview

IB Geography > Option C - Physical processes and landscapes > Flashcards

Flashcards in Option C - Physical processes and landscapes Deck (49)
Loading flashcards...
1
Q

plucking

A

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.

2
Q

abrasion

A

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

3
Q

cirques (corries)

A

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

4
Q

formation of corries

A
  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)
5
Q

pyramidal peaks

A

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.

6
Q

aretes

A

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

7
Q

glacial troughs (U-shaped valley)

A

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

8
Q

hanging valley

A

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

9
Q

roche moutonee (sheepback)

A

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

10
Q

formation of roche moutonee (sheepback)

A

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

11
Q

moraines + example

A

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

12
Q

characteristics of moraines

A

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

13
Q

drumlins + example

A

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

14
Q

erratics + example

A

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

15
Q

freeze-thaw

A

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

16
Q

solifluction

A

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

17
Q

frost creep

A

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

18
Q

process of frost creep

A

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

19
Q

thermokarst

A

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

20
Q

process of thermokarst

A

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

21
Q

pingo

A

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

22
Q

formation of pingos

A

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

23
Q

patterned ground + example

A

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

24
Q

formation of patterned ground

A

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

25
Q

permafrost

A

permanently frozen ground

26
Q

types of permafrost

A

continuous
discontinuous
sporadic

27
Q

continuous permafrost

A

-5 to -50 degrees

28
Q

discontinous permafrost

A

-1.5 to -5

29
Q

sporadic permafrost

A

0 to -1.5

30
Q

active layer

A

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

31
Q

weathering

A

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

32
Q

why is wind erosion more pronounced in arid environnmets?

A

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

33
Q

salt crystallisation

A

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.

34
Q

disintegration

A

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.

35
Q

types of rivers

A

exotic/exogenous river
endorheic river
ephemeral river

36
Q

exotic/exogenous river

A

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

37
Q

endorheic river

A

those that drain into an inland lake or sea

38
Q

ephemeral river

A

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

39
Q

sand dunes

A

a mound of sand formed by the wind

40
Q

formation of sand dunes

A

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

41
Q

yardangs

A

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

42
Q

formation of yardangs

A

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

43
Q

zeugens

A

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

44
Q

formation of zeugens

A

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

45
Q

mesas

A

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

46
Q

buttes

A

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

47
Q

wadis

A

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

48
Q

formation of wadis

A

formed by flash floods or during wetter pluvial periods

49
Q

characteristics of glacial deposits

A

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.