Aeolian Processes and landforms

Question 1

What are aeolian processes/landscapes

Answer 1

• processes and landforms related to the action of wind
• widespread, but concentrated in arid environments
• weaker force than water

Question 2

what are the 3 factors to sediment transportation in aeolian processes?

Answer 2

traction, saltation and suspension

Question 3

What are the four mechanisms at work in aeolian processes?

Answer 3

gravity, friction, drag, lift

Question 4

What is traction?

Answer 4

• dominated by drag force
• usually larger and denser particles are moved this way

Question 5

What is saltation?

Answer 5

• instigated by pressure differences at the bed and in the flow profile
• bouncing and jumping
• medium sands and grains

Question 6

What are controls on the erosivity of wind?

Answer 6

1. wind velocity
2. grain size
3. surface cover

Question 7

Why is surface cover important on the erosivity of wind?

Answer 7

• there is no wind erosion on a vegetated surface!!
• continuous cover raises the laminar boundary layer, so no sediment below this will be moved

Question 8

What is a deflation hollow?

Answer 8

• erosional aeolian landform
• shallow depression produced by the entrainment of grains
• like scooping out a bowl of sediment

Question 9

What are desert pavements?

Answer 9

• the winnowing of fine material away from a landscape, only leaving coarser, immobile clasts behind
• fine material will settle under the clasts

Question 10

What are yardangs?

Answer 10

• erosional landforms made by abrasion/sandblasting
• wind abraided ridges oriented with the prevailing winds and separated by abraded chutes that conduct windblow sand

Question 11

What are ventifacts?

Answer 11

• landforms made by abrasion
• stone planed by abrasion,
• similar to yardangs
• w changing direction of dominant winds, different facets merge along sharp ridges
• usually only one side is abraided

Question 12

What are some erosional aeolian landforms?

Answer 12

• desert pavements
• Yardangs
• ventifacts

Question 13

what are ergs?

Answer 13

• type of depositional aeolian landforms
• essentially thick sand deposits

Question 14

What are the 3 main factors that control the type of dunes that form?

Answer 14

• wind strength
• vegetation
• sand supply

Question 15

What are dunes?

Answer 15

• depositional aeolian landform
• hills of loose sand formed by wind
• initiated by changes in surface roughness, shedding from anchored dunes, bursts of higher velocity or more turbulant wind

Question 16

for dunes, the steeper side is the _______ side

Answer 16

LEE SIDE

Question 17

What are some dune types?

Answer 17

• longitudinal
• Barchan
• parabolic

Question 18

What are longitudinal dunes?

Answer 18

• dunes formed from high wind strength
• oriented parallel to wind direction
• limited sand supply and limited vegetation

Question 19

What are barchan dunes?

Answer 19

• dunes formed from unidirectional, moderate winds
• semi-abundant sand supply
  -usually isolated
• “c” shape

Question 20

What are parabolic dunes?

Answer 20

• similar to barchan, but opposite
• “D” shape like

Question 21

What is loess?

Answer 21

• dust/silt sized material that gets picked up by winds, moved large distances in suspension
• produced by glacial communion or fluvial systems