Permafrost

Question 1

Permafrost is…

Answer 1

ground below 0 for 2+ years

Question 2

Periglacial

Answer 2

things affected by freeze thaw

Doesn’t have to include permafrost (Edmonton dominated by freeze/thaw but we don’t have permafrot)

Question 3

Active Layer

Answer 3

Top layer that seasonally thaws

Where max temp crosses 0 degrees

Question 4

Base of permafrost is…

Answer 4

where temp crosses back to 0

Question 5

Depth of zero amplitude

Answer 5

• where min and max temps meet
• above is affected by seasonal temp changes
• below is affected by geothermal gradient

Question 6

Latitudinal distribution

Answer 6

moving (cooling) towards the poles

Question 7

Elevational distribution

Answer 7

lapse rate, more permafrost higher up because of colder temps the higher up

mediated by aspect

Question 8

continuous permafrost

Answer 8

90% of ground underlain by permafrost

Question 9

extensive discontinuous

Answer 9

50-90% of ground underlain by permafrost

Question 10

sporadic discontinuous

Answer 10

10-50% ground underlain by permafrost

what we have in northern parts of provinces (the rest are in the territories)

Question 11

Talik

Answer 11

a zone in a permafrost region, without permafrost

Question 12

Degree Day (DD)

Answer 12

difference on a given day from the mean temp in either DDfreeze (below mean) or DDthaw (above mean)

Question 13

Wedging

Answer 13

prying apart of Earth’s materials due to growh of ice

Question 14

Blockfield

felsenmeer

Answer 14

low gradient accumulation of cracked bedrock due to excessive ice wedging

Question 15

Rock Glaciers

Answer 15

• alpine permafrost
• accumulation of coarse material on a slope with interstitial ice or ice core
• moves by ice creep

Question 16

frost heave

Answer 16

displacement of materials due to growth of an ice lens with materials

Question 17

Earth hummocks caused by …

tundra tussocks

Answer 17

persistent frost heave

Question 18

Stone stripes

Answer 18

linear patterns of sorting on periglacial slopes

due to frost heave

Question 19

frost creep

Answer 19

downslope movement of sediment due to frost heave and thaw settling

Question 20

gelifluction

Answer 20

slow flow of saturated material moving over permafrost

Question 21

solifluction lobes

Answer 21

slow downslope movement of material due to frost creep and gelifluction

Question 22

frost pulling

Answer 22

clast stuck in frozen ground and pulled up as frsot heaves, sediment fills void below, so net up-pulling when thawing

Question 23

frost susceptibility determined by

Answer 23

grain size (3% silt or more is susceptible) and long and slow freezing for ice lens growth

Question 24

difference between frost boil and sorted stone circles

Answer 24

coarse ring - sorted stone
finer center - frost boil

Question 25

Open-system pingo

Answer 25

migration of water downslope from below permafrost and in taliks at the base of a hill

discontinuous permafrost regions

Question 26

Closed-system pingo

Answer 26

water aggregates from a water source below or internal of the hill

continuous permafrost regions

Question 27

thermal contraction cracking

frost cracking

Answer 27

thin crack appears due to cooling and contraction of medium, ice wedges freeze below active layer and persist in permafrost

requires rapid cooling, doesn’t happen every winter

Question 28

peatlands and permafrost

Answer 28

high insulators in the summer - keep hot air out
great thermal conductors - move heat from gorund into air in winter

great for permafrost resilience

Question 29

peatland distirbution similar to _______ permafrost distibution

Answer 29

sporadic and extensive discontinuous

Question 30

palsa and peat plateuas similarities

Answer 30

ice covered land forms in peatlands, segregated ice growth causes them, drier peat due to further from water table

Question 31

palsa and peat plateau difference

Answer 31

palsa - hill
pp - plateau, flat, much wider

Question 32

thermokarst

Answer 32

landform associated with deformation of permafrost, caused by quick surface disturbance or slow climate change

only occur where excess-ice, – caves, sinkholes, karst lakes, etc

Question 33

retrogressive thaw slump

Answer 33

backwards erosion into a slope after surface disturbance of ice rich ground

positive feedback of exposed pfrost, thaw, mass mvmt, exposed pfrost, etc

Question 34

active layer detachment slide

Answer 34

shallow slope failure, translateral movement downslope sliding along base layer

due to climate change or surface disturbance

Question 35

mitigating permafrost thaw

Answer 35

thermosiphons (heat exchangers to cool ground in winter), avoiding permafrost, building on stilts, avoiding ground disturbance, gravel pads (allows for convection and no excess ice)

Question 36

thermosiphons

Answer 36

have a liquid with low boiling point at bottom, draws in heat from ground, and evaporates out, upwards and into the air