Ice

Question 0

Describe permafrost

Answer 0

The permanently frozen ground has a top layer that can melt in the summer, this is the active layer. 20 to 25% of the earths land is permafrost.

Question 1

What is permafrost?

Answer 1

Permanently frozen ground

Question 2

What can areas of permafrost be …

Answer 2

Continuous and discontinuous

Question 3

What Is discontinuous permafrost?

Answer 3

Only patches are frozen.

Question 4

What Is continuous permafrost?

Answer 4

All the ground is frozen.

Question 5

How can discontinuous permafrost form?

Answer 5

The mean annual temperature must be below 0 degrees for at least 2 years.

Question 6

How can continuous permafrost form?

Answer 6

The mean annual temperature must be below -5degrees

Question 7

Is the permafrost layer permeable or impermeable?

Answer 7

Impermeable

Question 8

If the temperature gets above 0 degrees in the summer what happens?

Answer 8

The active layer melts but the water can’t go anywhere, the active layer therefore gets waterlogged and will easily flow wherever there is a gradient. This is called solifluction.

Question 9

What’s solifluction?

Answer 9

In relation to permafrost, in the summer if the temperature goes above 0 degrees the active layer melts so water can’t go anywhere. The active layer gets water logged and will flow downhill wherever there is a gradient.

Question 10

Where do ice wedges develop?

Answer 10

In the permafrost soil

Question 11

Name some periglacal landforms?

Answer 11

nivation hollows, patterned ground, solifluction lobes, ice wedges and pingos

Question 13

How do ice wedges develop?

Answer 13

This is a periglacal landform. They are developed through ground contraction. This is the refreezing of the active layer during the winter. The cold causes the soil to contract. Cracks appear on the surface due to tension. The following summer the surface thaws and the cracks fill with meltwater. In the next winter the surface contracts and the water in the cracks freezes causing them to widen and deepen to from ice wedges.

Question 13

What is frost heave?

Answer 13

Water freezing the ground can make humps on the surface. When the active layer freezes in either he ice forms a lens shape. In fine grained soil the ice lifts up the surface layers if the soil.

Question 14

What is ground contraction in relation to ice wedges?

Answer 14

Ground contraction is the refreezing of the active layer during the winter.

Question 16

How is patterned ground formed?

Answer 16

Frost heave

Question 17

What is patterned ground?

Answer 17

In periglacial areas heat comes from the surface. On the surface there are fine grains and larger stones. The larger stones have a lower heat capacity so they can cool quickly. This is because in large stones only the surface is heated, in smaller stones the whole stone is heated . The talic around doesn’t freeze but the water under the stones freezes as it is protected from being heated by the stones forming a ice lense. The stones block heat from the water so it freezes, during this it expands pushing the stones upwards. It is then held in place as the ice lens melts and fills with sediment, this process repets and eventually the stone will reach the surface. The ice underneath forms a mound so the stone roll downhill.

Question 18

Give some examples of periglacial areas

Answer 18

Northern Russia, Alaska and Northern Canada.

Question 19

What is talik?

Answer 19

any unfrozen material within the permafrost layer.

Question 20

How big can ice wedges be?

Answer 20

1m in width and 3m in depth.

Question 21

What must there be from patterned ground to be formed?

Answer 21

area of land with fine grown soil and larger stones dotted around

Question 22

What are pingos?

Answer 22

Ice filled periglacial hills

Question 23

What types of pingos are there?

Answer 23

Open, closed and ruptured

Question 24

What process forms pingos?

Answer 24

Groundwater freezing

Question 25

How are open system pingos formed?

Answer 25

There must be an ice core in the permafrost layer. The permafrost is creating hydrostatic pressure on the water from outside he system. The permafrost therefore pushes the water up which pushes the ice core upwards creating a mound.

Question 26

How are closed system pingos formed?

Answer 26

There must be a lake with sediment in the floor insulating the ground underneath creating talik. When the lake dries up the ground isn't insulated anymore The permafrost at the sides is pushing the talik inwards. Water collects at the centre of the talik which causes it to freeze. Once as ice core is formed it's pushed inwards due to pressure.

Question 27

How's a ruptured pingos formed?

Answer 27

As e surface ruptures heat enters which melts the core and the lingo collapses .

Question 28

What process forms nivation hollows?

Answer 28

Nivation

Question 29

What's processes make up nivation?

Answer 29

Solifluction, freeze thaw and meltwater

Question 30

How are nivation hollows formed?

Answer 30

Nivation deepens hollows. Snow gets into hollows in the ground freeze thaw occurs as the temperature changes from day to night. Freeze thaw weakens the rock breaking it up. When the snow melts it carries away the broken rock. Gravity moves them downhill.

Question 31

What process makes solifluction lobes?

Answer 31

Solifluction

Question 32

How are solifluction lobes created?

Answer 32

During the winter the active layer freezes and so does the underlying layer. The next summer the active layer thaws by the underlying layer stays frozen and so acts as impermeable rock. The surface meltwater can't infiltrate and it is too cold for evaporation. Any topsoil will become saturated and flow over the frozen ground . It then flows downhill and forms solifluction lobes. Can be 50m in width.