Periglacial Shite

Question 1

What are the 3 types of permafrost?

Answer 1

Continuous
Discontinuous
Sporadic

Question 2

What is continuous permafrost?

Answer 2

Found in coldest regions
Little thawing in Summer
-5 to -50 degrees
Up to 700m in Canada

Question 3

What is discontinuous permafrost?

Answer 3

Slightly warmer conditions
Breaks in permafrost under lakes, rivers, sea etc
20-30m avg
-1.5 to -5 degrees

Question 4

What is sporadic permafrost?

Answer 4

Mean annual temp. just below freezing
Permafrost occurs in isolated spots
Local climate cold enough to prevent complete thawing
0 to -1.5 degrees

Question 5

What is permafrost?

Answer 5

Layer of soil, sediment, or rock below surface remains permanently frozen

Question 6

What is the active layer?

Answer 6

Topsoil in permafrost environments
Thaws in summer
Freezes in winter

Question 7

Which factors influence prescence of permafrost?

Answer 7

Rock + soil types (Depth)
Vegetation (Insulation)
Snow cover
Slope angle (Solar radiation)
Proximity to water bodies

Question 8

List periglacial processes

Answer 8

Freeze thaw
Nivation
Frost heave
Groundwater freezing
Solifluction
Meltwater erosion

Question 9

List periglacial landforms

Answer 9

Nivation hollows
Patterned ground
Ice wedges
Pingos
Solifluction lobes
Braiding
Scree
Loess

Question 10

Which landform does freeze thaw create?

Answer 10

Scree

Question 11

Which landform does nivation create?

Answer 11

Nivation Hollow

Question 12

Which landform does frost heave create?

Answer 12

Patterned ground
Some pingos

Question 13

Which landform does groundwater freezing create?

Answer 13

Pingos

Question 14

Which landform does solifluction create?

Answer 14

Solifluction lobes

Question 15

Which landform does meltwater erosion create?

Answer 15

Braiding

Question 16

How is a nivation hollow created?

Answer 16

Snow falls into hollow/depression
Protected from wind + sun
Compaction by further snowfall
Underlying rocks weakened + eroded

Question 17

How is a solifluction lobe created?

Answer 17

Active layer thaws
Meltwater reduces friction between soil particles
AL moves downslope
Rounded tongue like features form terraces in valley

Question 17

What is gelifluction?

Answer 17

Combination of solifluction with frost heave and permafrost

Question 18

How is patterned ground created?

Answer 18

AL freezes, ice lenses develop
Soil volume rises + forced upwards
Frost heave - fine grain soil expands unevenly
Stones heat up faster than ground, cool + expand when ground freezes
Freeze thaw, crystals heave rocks upwards

Question 19

How is an ice lens created?

Answer 19

Soil moisture becomes free
Lens develops
Fed by water from capillary action + movement through frost susceptible soil
Lens expands, land lifts + heaves

Question 20

What are the 2 types of pingo?

Answer 20

Open system
Closed system

Question 21

How is a pingo formed?

Answer 21

Groundwater freezes into ice lens
Lens trapped within layers of land
Lens forces overlying land + sediments upwards

Question 22

What is the difference between the 2 types of pingo?

Answer 22

OS - Water able to seep through permafrost
CS - Water unable to seep through frozen ground

Question 23

How is an ognip created?

Answer 23

Pingo grows overly large
Lens exposed
Lens melts
Pingo collapses

Question 24

How is an ice wedge created?

Answer 24

AL freezes in winter
Soil contracts
Surface cracks
Cracks fill with water
Freeze thaw