Wind Erosion and Desert Features Flashcards
(84 cards)
1
Q
Is there flowing water in deserts?
A
no
2
Q
what is the main force/agent/source of erosion in deserts?
A
wind
3
Q
the main erosive mechanism within wind is ____ that is carried along in it.
A
sand
4
Q
What are the three processes moving wind-blown sediments?
A
- surface creep - salutation - suspension
5
Q
_____ ______ rolls large sized along the ground
A
surface creep
6
Q
_____ moves medium sized grains (in this instance _____ - sized grains)
A
saltation, sand
- saltation is a series of short jumps in which the particles move along with the wind
7
Q
______ moves small/fine sized grains (in this instance _____ -sized grains)
A
suspension, dust
8
Q
What does suspension of sand cause?
A
dust storms
9
Q
______ is the process by which particles are moved across the surface of rocks and acts as sandpaper smoothing those surfaces.
A
Abrasion
10
Q
what are features formed by wind erosion?
A
arches, pillars,
11
Q
______ occurs in areas where there is little to no vegetation
A
deflation
12
Q
What happens in deflation?
A
small particles such as clay and silt are blown away by the wind
13
Q
In deflation _____ particles are blown away by the wind
A
small
14
Q
what are the small particles that are blown away by deflation?
A
clay, silt
15
Q
desert pavement forms from the process of _____
A
deflation
16
Q
What are the mechanisms/processes of wind erosion?
A
- abrasion
- deflation
- desertification
17
Q
What are the three products of abrasion?
A
- ventifacts -
18
Q
What are the three products of abrasion?
A
- ventifacts
- arches
- hoodoos
19
Q
Ventifacts often indicate _____ direction
A
wind
- Ventifacts can be important in seeing the prevailing wind directions in the present as well as in the past
20
Q
What are ventifacts?
A
rocks that have been shaped by the wind
21
Q
In the process of _______ wind-blown particles blow against the surface of rocks
A
abrasion
22
Q
The main course of erosion in deserts is _____
A
wind
23
Q
What are the three features that can form as a product of abrasion?
A
- ventifacts
- arches
- voodoos
24
Q
What are the three features that can form as a product of abrasion?
A
- ventifacts
- arches
- hoodoos
25
\_\_\_\_\_\_\_ are wind-blown pillars
Hoodoos
26
Hoodoos can indicate wind \_\_\_\_\_\_.
- direction
Especially if they are older they can indicate how wind directions have been in the past and if they have changed at all
27
Where does deflation occur?
In areas where there is little or no vegetation
28
\_\_\_\_\_\_\_\_ is the process by which small particles (such as clay and silt sized-particles) are removed by the wind and larger particles are left behind
Deflation
29
Deflation is the process by which ______ particles are removed by the wind and ______ particles are left behind
small, large
30
\_\_\_\_\_ particles, over time, will be blown away and as these particles are blown away there will be a concentration of ____ particles on the surface.
small, large
31
As small particles are blown away the surface _____ down in a process called \_\_\_\_\_.
drops, deflation
32
A product of _____ is desert pavement?
deflation
33
What is a product of deflation?
desert pavement
34
As smaller particles continue to be ______ you eventually reach the point where there are no small particles left on the surface.
removed
35
When no further deflation can occur _____ \_\_\_\_\_ arises.
desert pavement
36
What are two features or products of wind erosion?
- dunes
- floods
37
\_\_\_\_ are wind deposited ridges or hills of sand
dunes
38
What are dunes?
wind deposited ridges or hills of sand
39
What is a feature of a sand dune?
- typically asymmetrical in shape
40
Dunes are typically asymmetrical in shape meaning that there is a ____ face and a ____ face
longer, shorter
41
The ______ face is the face that faces the prevailing wind direction
windward
42
The longer face of dunes are called the _______ face
windward
43
The shorter face is called the ______ face
leeward, slip
44
What is a feature or characteristic of the windward face?
- it faces the prevailing wind direction
45
What is a feature or characteristic of the leeward face?
- it is steeper
46
Wind blows up the ______ face and blows down the _______ leeward face
windward, leeward
47
Does wind blow up or down the windward face?
up
48
Does wind blow up or down the leeward face?
down
49
Are dunes constantly growing and shaping?
yes
50
There are many different ______ of dunes that vary based on a few different \_\_\_\_\_
types, factors
51
What are the types of dunes?
- Barchan
- Star
- Parabolic
- Longitudinal
- Transverse
52
\_\_\_\_\_\_ dunes are crescent shaped
Barchan
53
\_\_\_\_\_\_ dunes migrate across the desert as the sand continues to blow.
Barchan
54
\_\_\_\_\_\_ dunes are a blown out U-shaped dunes
Parabolic
55
The _____ of parabolic dunes are anchored in some sort of _____ and then the wind blows out a ______ curve
legs, vegetation, concave
56
\_\_\_\_\_\_ dunes form parallel to the prevailing wind direction
Longitudinal
57
\_\_\_\_\_\_ dunes form perpendicular to the prevailing wind direction
transverse
58
Do transverse dunes form parallel or perpendicular to the prevailing wind direction?
perpendicular
59
Do longitudinal dunes form parallel or perpendicular to the prevailing wind direction?
parallel
60
Which type of dune can form when a number of barchan dunes form together into lines?
transverse
61
What are the three factors that influence dune formation and behavior?
- wind
- vegetation
- sand supply
In any particular desert the wind speed and direction, the sand supply, and the amount of vegetation combine to form different types of dunes.
62
What is a unidirectional wind?
a wind that always blows in one direction
63
What is no direction preferred?
wind that intermittently blows from all directions
64
Barchan dunes form in deserts that have a wind coming primarily from ____ direction
one
65
Star dunes form in areas where there is ___ \_\_\_\_\_\_\_ wind direction.
no preferred
66
Which type of dune tends to form in deserts that have a lot of sand?
Transverse dunes
67
Which type of dune tends to form in deserts that have low sand supply?
Longitudinal dunes
68
When there is a rain event in a desert they often result in _____ \_\_\_\_\_\_
flash floods
- a flash flood has a lot of water and sediment being carried over a short time. The water is muddy, has a high load, and is transporting a lot of material in a very short of time.
69
Why does flash flooding happen in deserts?
Because deserts are very dry, the introduction of water is going to have a strong erosive force
70
What features do flash floods deposit?
alluvial fans
71
Many alluvial fans coalesce into a \_\_\_\_
bajada
72
What is a bajada?
Many alluvial fans
e.g.
death valley
73
a flash flood has a lot of ____ and _____ being carried over a short time.
water, sediment
74
As flash floods run down a slope and empty into some valley or plane they _____ material in the shape of a fan.
deposit
75
If many alluvial fans begin to overlap they form a feature that is known as a \_\_\_\_\_
bajada.
76
The process of ______ is the creation of desert conditions in areas that were previously not deserts.
desertification
77
Can desertification be influenced by human activity?
yes
78
Is desertification a natural process?
yes
79
What are the signs of desertification?
- lowering water tables
- Higher salt content in soil and water
- High rates of soil erosion
- Destruction of vegetation
80
What is an example of desertification?
the Dust Bowl
81
How did the Dust Bowl occur?
poor farming practices combined with a drought caused a bit of desertification in the midwest as a lot of soil was blown away in a short amount of time
82
One of the great projects during the time of the Dust Bowl was to create a _____ \_\_\_\_ across the planes to prevent any further loss of soil
tree belt
83
What areas are susceptible or vulnerable to desertification?
- semi-arid areas near deserts
- poor soil management in intensely farmed areas
84
In semi arid areas farmers have to be _____ of soil management to prevent loss of soil in order to preserve their food source.
mindful
