periglacial landforms not finished. p52

Question 1

ice wedges

Answer 1

• develop in permifrost soil
• when the temp is very low, the ground contracts, causing cracks to form in the permifrost.
• when the temp increases, the active layer thaws and meltwater seeps into the cracks
• the permifrost layer is still frozen, so the water freezes in the cracks.

Question 2

patterned ground

Answer 2

this is where stones are arraned on the permifrost surface in circles, polygons of stripes.

Question 3

frost heave

patterned ground

Answer 3

happens when water underneat the stones freezes and expands. this forces the stones upwards. once the stones have reached the surface, they roll down the edges of the mounds that have formed, forming circles around them.

Question 4

frost contraction

patterened ground

Answer 4

frost contraction causes the ground to creack in polygon shapes. the cracks fill with stones, forming raised polygon patterns on the surface

Question 5

pingo!

Answer 5

pingos are a conical hill with a core of ice.
* they can be 90m high and 500m wide
* there are two types of pingos, open system

Question 6

open system pingo

Answer 6

• form where there is discontinuous permifrost
• groundwater is forced up through the gaps between areas of permifrost
• the water collects together and freexes, forming a core of ice that pushes upwards to create a dome

Question 7

closed system pingo

Answer 7

• form in areas of continuous permifrost where there is a lake on the surphace
• the lake insulates the ground , so the area beneath is remains unfrozen
• when the lake dries up, the ground is no longer insulated, and the permifrost advances around the area of unfrozen ground
• this causes water to collect in the center of unfrozen ground

Question 8

loess fields

Answer 8

a loess field is a large area full of wind-blown sediment.
- this sedement is often fine material that has been deposited on outwash plains
- strong winds blow the fine, erodited silt material across a plateau that is unobstructed by trees.
- the loess improces the soil which is used to set up suitable farms in warmer areas

Question 9

Case Study

The tundra environment of Northern Canada

Answer 9

• permifrost extends across 40-50% of canda.
• there are just over 1300 pingos, the tallest of these being 49m and esitmated to be 1000yrs old
• human actions and climate change could threaten the different areas of permifrost
• rising temptetures could significantly alter tundra environments. a warmer climate could cause carbon stored in the permifrost to be released, further causeing temps to rise