Frost and Wind

Question 1

What is the peri-glacial concept?

Answer 1

Processes in cold-but not glacial environments, more subtle than glacial processes

Question 2

What’s more common in Britain? Glacial processes or peri-glacial processes?

Answer 2

Peri-glacial processes

Question 3

What are para-glacial processes? Give an example

Answer 3

Non-glacial processes greatly affected and conditioned by glaciation or deglaciation.
e.g. sediment transfer process may greatly increase after deglaciation if a slope is unstable after ice-retreat.

Question 4

What’s the difference between peri-glacial processes and para-glacial processes?

Answer 4

Peri: cold but non glacial
Para: non-glacial but affected by glaciers

Question 5

What is cryotic ground?

Answer 5

Ground with a temperature below 0

Question 6

What is permafrost?

Answer 6

Ground that remains below 0 for at least 2 consecutive years

Question 7

What is seasonally cryotic ground?

Answer 7

Ground that undergoes seasonal thawing and freezing

Question 8

Describe the general typical effect of frost weathering.

Answer 8

Rocks often fracture along pre-existing weaknesses, this can cause rock disintegration and create fine material that then settles to leave a coarse top layer

Question 9

What is the difference between macrogelivation and microgelivation?

Answer 9

macro: produces larger clasts
micro: produces finer debris

Question 10

What types of rocks are more susceptible to microgelivation?

Answer 10

smaller debris –> Micaceous rocks (commonly igneous and metamorphic)

Question 11

What types of rocks are more susceptible to macrogelivation?

Answer 11

larger debris –> massive schists, gneisses, granulites

Question 12

What are the main 4 processes by which micro and macrogelivation take place?

Answer 12

Splitting
Flaking
Granular disintegration
Comminution

Question 13

What is solifluction?

Answer 13

Slow downslope movement of soil under seasonal thawing and freezing.

Question 14

What is frost creep?

Answer 14

Repeated swelling and resettling of soil/sediment

Question 15

What is gelifluction?

Answer 15

Slow saturated flow during the thawing of ice rich soil

Question 16

What is plug-like flow?

Answer 16

Localised sliding within clay rich soils due to thawing and melting

Question 17

Name three types of solifluction.

Answer 17

Frost Creep, Gelifluction, Plug-like flow

Question 18

What are block-deposits?

Answer 18

A surface cover of boulders with little or no fine material in the gaps

Question 19

What is the difference between autochthonous blockfields and allochthonous blockfields?

Answer 19

auto –> result of weathering of rocks that were already there
allo –> glacial deposits weathered

Question 20

What is the general 3 stage process of blockfields forming?

Answer 20

macrogelivation
then solifluction (moving downslope)
then immobilisation (no fine material to move boulders)

Question 21

What age are blockfields usually?

Answer 21

Can be relic features from the Neogene protected by glaciers or caused by weathering during glacial periods in the Quaternary

Question 22

What are debris-mantled surfaces and slopes?

Answer 22

Poorly sorted stony surfaces with a mix of larger clasts and a fine matrix (fine sediment)

Question 23

What is a diamict?

Answer 23

A poorly sorted deposit

Question 24

What is a tor?

Answer 24

A residual section of bare bedrock on high ground

Question 25

What are the two possibilities for explaining the formation of tors?

Answer 25

- Preferential deep weathering of densely jointed bedrock - Removal of regolith around hard rock by solifluction and frost weathering

Question 26

What is relic-patterned ground?

Answer 26

terrain with surface patterns defined by micro-relief rocks, vegetation cover and fine and coarse debris.

Question 27

What are the two types of relic patterned ground? What causes them?

Answer 27

Sorted: differential frost heave Unsorted: same as sorted but without a concentration of clasts.

Question 28

What are solifluction landforms?

Answer 28

Landforms on gentle to moderate slopes, often occur on larger hills/mountains but terminating at a steep rise or step

Question 29

What are solifluction sheets?

Answer 29

A continuous top layer of frost-weathered deposit over bedrock - successive sheets can look like stairs

Question 30

What are solifluction lobes?

Answer 30

Lobate extensions of sheets on steeper gradients, can override sheets on downslope ends

Question 31

What are talus deposits?

Answer 31

deposits at the bottom of steep rock walls - predominantly through rockfalls

Question 32

What is a frost related cause of rock falls?

Answer 32

Macrogelivation

Question 33

What are 3 types of talus deposits?

Answer 33

Sheets - uniform delivery of the debris. Cones - concentrated or funnelled in certain spots. Coalescing cones - cones that intersect laterally.

Question 34

What are deflation surfaces? What causes them?

Answer 34

Surfaces with almost all vegetation and loose sand stripped away - carpeted with fine gravel and flat lying boulders. - Caused by strong wind

Question 35

What are deflation scars? What causes them?

Answer 35

Patches of bare ground in vegetated terrain - Caused by needle ice action and wind erosion

Question 36

What are wind stripes?

Answer 36

Selective wind erosion on plateaux surfaces, stripes of vegetation and bare ground perpendicular to dominant wind direction

Question 37

What are wind polished boulders? What do they tell us?

Answer 37

Wind erosion on bedrock and boulders caused by transfer of KE to rock particles over a long time - can evidence wind direction

Question 38

What is debris flow activity? What are the two types?

Answer 38

Rapid downslope flow of poorly sorted debris when it’s mixed with water. Either Hillslope debris flow (usually initiated by a landslide) or valley confined which is usually initiated by water pressure in sediment.

Question 39

What does alluvial mean?

Answer 39

Alluvial refers to the stuff left behind by running water.

Question 40

Why are most alluvial landforms paraglacial?

Answer 40

Because most of the sediment carried in upland rivers is reworked glacial sediment.

Question 41

What are alluvial river fills?

Answer 41

Deposits of sediments in a river

Question 42

What are river terraces?

Answer 42

major steps in a valley side corresponding to previous river flow

Question 43

What are alluvial fans?

Answer 43

low gradient fans caused by tributary streams that end in one trunk valley