periglacial environments

Question 1

permafrosts

Answer 1

• rock or soil material that has remained below )c for two of more years
• upper surface thaws in summer (active layer)
• permafrost table” limit of seasonal thawing; talic which is unfrozen waer
• permafrost is melting which is NOT GOOD

Question 2

why important to canadaisn

Answer 2

• 40% land area underlain by permafrost (50% 1970-1990s)
• 10-15% of earths total land area
• common in periglacial environments

Question 3

periglacial envionements

Answer 3

-area/ regions where landforms and geomorphic processes are influecne by seasonal thawing and freezing, often in areas of permafrost
- freexing and thawing affects landforms
- does not relate to glacirs

Question 4

distribution of permafrost

Answer 4

• high latitude areas (arctic regions): continuous permafrost;up to 700m thick; mean annual air temps <-7C
• towards south: discontinous permafrost; thins to only few meters, patchy and sporadic; mean annual air temps >-7C

Question 5

ground ice

Answer 5

• frozen mositure below earth’s surface
• varies from small amount in pore space to large ice bodies
• clear or colourful ice
• not glaciers
• froszen water mosture stored in soil
• seen in North

Question 6

ground ice forms

Answer 6

• pingo ice
• ice wedges
• polygons

Question 7

pingo ice

Answer 7

• indicative of periglacial environemnts
• relatively clear permafrost
• occurs horizontally or in les-shaped masses
• 3-54m in height, 30-450 in diameter
• ibyuk in Northwest teritories

Question 8

ice wedges

Answer 8

• permafrost formed in alrge ice wedges or masses with apralle or subparalle foliation
• foliated ice occurs as wedges, vertical or inclined sheets
• 2.5 cm-3m high and 0.3-9m high
• cracks
• every winter, freeze, thaw, freeze, thaw.. and builds by adding more mositure
• beauforst sea coast, canada

Question 9

polygonal ground

Answer 9

• micro relief patern on the ground
• covers thousand of km^2 in the arctic
• ice wedges are below these polygons
• little mounds are less than 1m
• Tuktoyaktuk, northwest teritories

Question 10

what does disturbance of ice ground cause

Answer 10

• melting of ice

thermokarst:
- erosioal process unique to perma frost
- process by which characteristic landforms results from the thawing of ice-rich permaforst and/or melting of massice ice
- not an actual landform, is an EROSIONAL PROCESS
- causes: thermokarst lakes, gorund subsidece (road disturbance, house collapse), freethaw processes (water expands by 9% on freezing, can fracture rock), procudes frost-shattered screes, felsenmeer

Question 11

ice growth

Answer 11

• occurs preferentailly below stones in soil
• forms pipraker (needdle ice)
• ice lifts stones/ soil- frost heaving
• heaving produces sone polygon (no active erosion agent, just freeze and thaw pattern) and stone stripes

Question 12

slope processes

Answer 12

• active layer has high water pressures (prone to mass movement, liquifaction (solifluction)); failure of slopes due to high water constent
• slow downslope movement of soil- few cms/year, produces solifluction lobes/terraces

Question 13

creep

Answer 13

• very slow rates of movement
• can effect stability of built structures