❄️ glaciation sg6

Question 1

what is a periglacial area

Answer 1

areas with permafrost, seasonal temp variations & ftw cycles

Question 2

what are the characteristics of permafrost

Answer 2

ground remains frozen for at least 2 consecutive years and is overlain by an active layer

Question 3

what % of the earth is covered in periglacial landscape

Answer 3

25%

Question 4

what is solifluction

Answer 4

• upper layer of soil melts so water can’t drain away
• active layer of soil is saturated & moves downslope
• very slow mass movement so active layer moves downhill when slope is over 2 degrees

Question 5

what is nivation

Answer 5

occurs under permanent snow patch = enlargement of hollows

Question 6

what is frost heave

Answer 6

uplift of soil or individual stones within soil due to formation of ground ice

Question 7

what are pingos

Answer 7

rounded, ice core hills up to 90m high & 800m wide

Question 8

how does a pingo form

Answer 8

• water percolates through talik within permafrost
• groundwater from surrounding slopes collects on valley floor
• water rises to surface under artesian pressure and when it encounters colder ground it freezes
• ice lens continues to grow & becomes large
• this displaces the sand & gravel above to form a pingo

Question 9

how does an ognip form

Answer 9

when an ice lens grows so large that it ruptured surface so sun will melt the ice. done will collapse and a ridge is left around the circular depression

Question 10

what are the characteristics of patterned ground

Answer 10

stone stripes or polygons
1-5m in diameter
done height between 10cm-10m

Question 11

how does patterned ground form

Answer 11

• stones have high shc so when soil drips below 0^c water beneath a stone freezes = ice lens
• these grow & push stones up through soil
• temps rise so ice lens thaws but fine material infill under risen stones so stones can stay high up
• repeated ftw = stones pushed up & eventually reach surface
• frost heave = domed surface & surface stones roll downhill to edge of mounds

Question 12

how can patterned ground be modified with climate change

Answer 12

• permafrost thaws = depressions sink within polygon
• more meltwater in active layer = solifluction
• biological weathering

Question 13

what is a thermokarst landscape

Answer 13

areas of hummocky, irregular ground interposed by waterlogged depressions created as ground ice thaws.
depressions fill with water to form shallow lakes

Question 14

what is a positive feedback loop within thermokarst landscape

Answer 14

1. increases flows of energy into periglacial system
2. permafrost thaws = waterlogged depressions
3. water has higher shc = retains heat for longer than surrounding land
4. permafrost thaws
5. depth of active layer increases
6. more permafrost thaws
   back to 2.

Question 15

what human activity takes place in a periglacial landscape

Answer 15

• oilfields in prudhoe bay
• trans alaskan pipeline (tap): 800 miles long & transports oil from bay to valdez

Question 16

why does human activity take place in prudhoe bay

Answer 16

• in top 20 largest oil fields in the world
• provides 20% of country’s oil consumption
• takes dependency away from middle east for oil as it could be unreliable
• 1/3rd of Alaskan jobs

Question 17

what is the impact of human activity on flows of material

Answer 17

gravel taken from river beds to put under buildings = altered rates of erosion & deposition of gravel & in river

Question 18

what is the impact of human activity on flows of energy

Answer 18

• oil rigs & oil drilling release heat to ground
• has released & then burnt = fossil fuels = temp increase
• airstrips = lower albedo = more heat absorbed
• dust from gravel roads kill vegetation = less shade = melting

Question 19

how does removal of vegetation influence periglacial landscape

Answer 19

• deeper active later
• an area without vegetation will have an active layer 7m deeper than an area with vegetation after 26 years

Question 20

how does increased solifluction influence a periglacial landscape

Answer 20

• thawing of perfmasfrost = active layer is created = saturated material
• layer moves downslope

Question 21

how does an alas form

Answer 21

when an ice wedge melts and the depression fills with water. water evaporates when temps warm so lake is replaced with vegetation