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Geomorphology > periglacial environments > Flashcards

periglacial environments Flashcards

1
Q

what was periglacial originally used to describe

A

places near to or on the fringe of ice sheets or glaciers

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2
Q

what has the definition of periglacial changed to

A

areas with
- with permafrost
- with some seasonal temp variation
- mean temp in the summer is ABOVE 0
- freeze/thaw cycle dominates the landform creations
- distinctive ecosystem adapted to the periglacial envi

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3
Q

is the periglacial zone easy to live in

A

NO very hard to thrive

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4
Q

what process dominants the landform creating process in periglacial area

A

freeze-thaw

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5
Q

what is permafrost

A

permanently frozen ground where soil temps have remained BELOW 0 for AT LEAST 2 years

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6
Q

how long must soil temps remain below 0 for it to be considered permafrost

A

at least 2 years

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7
Q

what are the kinds of permafrost

A
  1. continuous
  2. discontinuous
  3. sporadic
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8
Q

how deep can continuous permafrost reach

A

up to 1500 meters

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9
Q

what is the mean annual air temp for permafrost to be deemed continuous permafrost

A

below -5 degrees ALL YEAR ROUND

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10
Q

how does summer temps affect continuous permafrost

A

only results in very superficial surface melting = very little if any melting of permafrost

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11
Q

where does continuous permafrost NOT extend

A

in all areas EXCEPT under bodies of water

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12
Q

what is continuous permafrost

A

a sheet of continuous frozen material ALL YEAR ROUND

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13
Q

what type of permafrost occurs in slight warm areas

A

discontinuous permafrost

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14
Q

describe a landscape with discontinuous permafrost

A

islands of permanently frozen ground SEPARATED by small pockets of unfrozen LESS COLD areas

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15
Q

why is zones with discontinuous permafrost slight warmer than continuous permafrost

A

because these zones have surface water bodies which warm the surrounding area based on water’s specific heat capacity

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16
Q

what is the mean annual temp for discontinuous permafrost zones

A

between -1 and -5 degrees

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17
Q

where does the continuous permafrost zone coincide

A

approximately with the 10C isotherm (where July temps do NOT rise above 10 degrees)

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18
Q

what mean annual temp supports sporadic permafrost

A

it being JUST BELOW 0 degrees

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19
Q

what does sporadic permafrost zones look like

A

isolated areas of permanently frozen ground remain BELOW the surface

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20
Q

what are summer temps for supporting sporadic permafrost

A

above 0 degrees

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21
Q

what are the two horizons in a permafrost profile

A
  1. active layer
  2. talik
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22
Q

contrast the active layer and talik layer for permafrost

A

active layer
- very mobile layer based on summer temps melting surface layer of permafrost

talik layer
- unfrozen material within the permafrost zone often UNDER bodies of water

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23
Q

what is the depth of zero annual amplitude

A

maximum depth affected by the annual temp variation

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24
Q

how does the depth of zero annual amplitude vary

A

based on air temp and type of soil

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25
Q

describe how above and below the zero annual amplitude affect permafrost differently

A

above the line permafrost is affected by temperature and will melt slightly in the summer

below the line permafrost will remain stable and frozen all year round

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26
Q

why is there so much water in permafrost zones

A

because there is no well established drainage system with the ground being frozen and water not being able to penetrate (so it sits ontop of the ground instead)

27
Q

Felsenmeer

A

exposed rock surfaces that have been quickly broken up by frost action so that much rock is buried under a cover of angular shattered boulders

28
Q

where is Felsenmeer common in Canada

A

Northern Manitoba

29
Q

what are two landscape features caused by frost wedging in permafrost zones

A
  1. Felsenmeer
  2. Patterned Ground
30
Q

what are two types of patterned ground

A
  1. stone circles
  2. ice-wedge polygons
31
Q

Stone circles

A

A type of patterned ground that consist of circular arrangements of slabs and small domes of mud with stony rims

32
Q

how were stone circles sorted to form the unique circle formations

A

based on many freeze/thaw cycles that sorted the surface debris where finer matter was heaved to the surface and coarser fragments around the edges

32
Q

how are stone circles produced

A

by the churning action of frost forming in UNSORTED glacial TILL and regolith

33
Q

what type of patterned ground in this is periglacial environments

A

stone circles

34
Q

what type of patterned ground in this is periglacial environments

A

ice wedge polygon

35
Q

where do ice wedge polygons occur

A

in permafrost peatlands

36
Q

what is an example of where to find ice wedge polygons

A

Hudson Bay Lowlands

37
Q

what do polygons mark in periglacial environments

A

location of massive ice wedges extending from the surface down 2 or 3 meters

38
Q

what are pingos

A

vegetated, ice cored mounds commonly formed above ponds or lakes

39
Q

how wide can pingos be

A

up to 100 meters across

40
Q

what happens in a pingo when the ice core grows TOO large

A

it will rupture the sediment cover and become exposed

41
Q

what are under pingos

A

large ice wedges

42
Q

what is this called in a periglacial environment

A

pingo

43
Q

what manner do pingos grow in

A

cyclic

44
Q

what type of system can a pingo form in

A

open AND closed

45
Q

open system pingo

A

those that receive water CONTINUOUSLY from ground water

46
Q

closed system pingos

A

form in regions with LIMITED GROUND WATER available SO use more melting permafrost

47
Q

Is this an open or closed Pingo

A

open system pingo

48
Q

Is this an open or closed Pingo

A

closed system pingo

49
Q

what are palsas

A

peat mounds with lenses of ice underneath

50
Q

where do palsas form

A

near surface water

51
Q

what periglacial feature is this

A

palsas

52
Q

what kind of topography is formed when permafrost MELTS

A

THERMOKARST topography

53
Q

what is thermokarst

A

the process where landforms result from the thawing of ice-rich permafrost and/or melting of massive ice

54
Q

what is thermokarst unique to

A

erosional process UNIQUE to permafrost with EXCESS ice

55
Q

what is thermokarst terrain characterized by

A

very irregular surfaces of marshy hollows and small hummocks formed when ice rich permafrost thaws

56
Q

does thermokarst have anything to do with ground or bedrock weathering

A

NO

57
Q

is there a lot of water in thermokarst topography

A

YES - based on huge amounts of ice melting

58
Q

how deep does permafrost penetrate in cryosolic soils

A

1 to 2 meters of the surface

59
Q

describe the soil characteristics if Cryosolic soils

A

mostly mineral with few organic soils because very little life can thrive

can be either wet OR dry

60
Q

what are two characterizing features of cryosolic soils

A
  1. always found in cold climates
  2. frozen soil conditions for MOST of the year (needs to be thawed at some point)
61
Q

is the soil profile of cryosolic soils little or big

A

little based on the soil taking so long to form

62
Q

what is a dead give away form Cryosolic soils

A

horizons being mixed with a flame like structure based on cryoturbation (uneven freeze thaw)

63
Q

what are impacts of thawing permafrost

A
  1. affects infrasture able to be built based on ground being unstable
  2. ecosystems are changing and organisms have to adapt
  3. leaking water to the oceans which affect water levels
  4. frees methane into the atmosphere = increases global warming

Geomorphology (12 decks)

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