Geologic processes powered by the wind are called __________ processes.

barchan
coriolis
eolian
yardang


Turbulence of air increases in proportion to the ___________ of the air flow.

volume
velocity
acceleration
distance


Due to the Coriolis effect, any current of air or water is deflected to the ____ in the northern hemisphere and to the _____ in the southern hemisphere.

east ... east
east ... west
west ... east
west ... west


The Earth rotates from _______ to _______ .

west ... east
east ... west
north .... south
south ... north


Sand grains saltating in air can jump higher than sand grains saltating in water because ___________ .

water is less dense than air
air is less viscous than water
wind velocity is faster than water velocity
grains are suspended in air longer than they are in water


Which of the following is an important source of dust?

volcanic dust from eruptions
clay minerals from soils
organic sources, including charcoal, pollen and bacteria
all of these


Cross beds in a lithified dune dip to the west. During deposition of the sand, the prevailing winds were probably from the __________ .

east
west
north
south


Large dune fields, or seas of sands, are called _______ .

draas
barchans
regs
ergs


Deserts with a pebble surface are called _________ .

draas
barchans
regs
ergs


Which of the following are not related to wind erosion?

loess
ventifact
deflation
blowout


The loess deposited in the upper Mississippi Valley was derived primarily from ________ .

volcanic dust
desert regions lying to the west
glacial deposits
coastal sand dunes


Why does volcanic dust tend to travel further than wind-blown dust derived from the continents?

because volcanic dust is erupted high into the atmosphere
because volcanic dust is less dense than dust derived from the continents
because volcanic dust is composed of quartz whereas dust derived from the continents is composed of feldspar
all of these


The Great Basin and Mojave deserts of western North America exist primarily _________ .

because they lie near the equator
because they lie thousands of kilometers from the ocean
because they lie in the rainshadow of coastal mountains
all of these


Much of a desert's surface consists of sand, gravel, and rock rubble because _________ .

clay minerals form slowly in a desert environment
wind blows away clay and soil before it can accumulate to great thickness
vegetation is sparse and cannot prevent erosion of soil
all of these


Which of the following would you least expect to find in a desert?

playa lakes
rounded, soil-covered hills
steep river valleys and gorges
dune fields


Which of the following is not a wind deposit?

pediment
sand dune
loess
all of these are wind deposits


A broad, gently-sloping platform of bedrock that is left behind as a mountain front is eroded is called a(n) ___________ .

pediment
alluvial fan
mesa
erg


Wind speeds of 117 kilometers per hour or more constitute a _______

moderate to strong breeze
moderate to strong gale
whole gale to storm
hurricane


In temperate zones of the Earth between 30^o and 60 ^o latitude, the prevailing winds come from the ________.

north
south
east
west


In the figure above, the letters A through D represent wind names. Which of the following is false?



A and B represent the "westerlies"
A and C represent "trade winds"
C and D represent "trade winds"
none of these statements are false


Ripples are generally oriented ________ to the current direction

parallel
30 degrees
45 degrees
perpendicular


In a large dust storm, approximately how much dust can 1 cubic kilometer of air carry?

1 ton
10 tons
100 tons
1000 tons


Fine-grained dust particles from the eruption of Mr. Pinatubo remained in the atmosphere for how long?

1 - 2 months
3 - 4 months
1 -2 years
3 - 4 years


White Sands National Monument contains sand dunes made up of _________?

quartz
gypsum
organic sources including pollen and bacteria
feldspar


What is the primary cause of frosting on the surface of quartz sand grains?

impacts with other sand grains
abrasion by air currents
slow dissolution by due
none of these


Which of the following statements is false?

wind is a more effective erosion agent in wet climates
wind is a more effective erosion agent in dry climates
wind is an equally effective erosion agent in wet and dry climates
wind does not cause erosion


The process by which the ground surface is lowered by wind erosion is called _______.

deflation
inflation
ablation
none of these


Which of the following will not accelerate deflation?

established vegetation
construction
motor vehicle tracks
plowing


How does desert pavement form?

by intense chemical weathering
by stream erosion
by intense mechanical weathering
by wind erosion


Yardangs are:

sand dunes arranged in long, parallel rows
eroded bedrock with long, parallel grooves
long, parallel ridges eroded by dust
none of these


Which of the following promote the development of sand dunes?

strong winds
a supply of loose sand
dry climate
all of these


Sand will accumulate ___________.

on the lee side (downwind) side of a boulder
on the windward side (upwind) of a boulder
on both the lee side and the windward side of a boulder
boulders cannot cause sand to accumulate




Given the relative positions of the sand dune and rock shown here, the wind direction is predominantly ___________

north to south to north
east to west
west to east


The steeper, downwind side of a sand dune is called a _________.

sand drift
ventifact
slip face
streamline


A cross bed preserved in an eolian sandstone represents _________.

the top of a former sand dune
the bottom of a former sand dune
the upwind side of a former sand dune
the downwind side of a former sand dune




This sand dune is a _______ dune

barchan
transverse
blowout
linear


The wind direction which would create this dune is __________.

north to south
south to north
east to west
west to east


In a barchan dune, the points of the crescent point ______ and the slip face is the ________ downwind curve of this dune

upwind .... concave
upwind .... convex
downwind .... concave
downwind ..... convex


Sand dunes behind beaches are typically_______.

barchan
transverse
barchans
linear dunes


During erosion loess tends to break off __________.

in horizontal layers
in vertical sheets
along irregular cracks
slowly, grain by grain


Which of the following is not related to wind erosion?

loess
ventifacts
deflation
blowouts


Long sand ridges that are more or less parallel to the prevailing wind are called ______.

barchan dunes
linear dunes
transverse dunes
blowouts


Through geologic time the interior of Australia has changed from a moist, humid climate to a desert because

plate collisions have built mountains near the coast line which block moisture-bearing winds from the continent's interior
Australia has moved northward into an arid, subtropical zone
Australia has moved southward out of the part of the more humid trade winds
the continent has grown through volcanic activity making the interior too far away from moisture-bearing winds


Radar imaging from the space shuttle Endeavor has provided evidence that the Sahara Desert __________.

has always been an arid environment
was once tropical with many different types of vegetation
once had an extensive system of river channels which are now dry
has sand dunes in excess of 300 m in height


The transformation of semi-arid regions into deserts is called _______.

deflation
deforestation
detoxification
desertification


What minerals are responsible for the orange-brown colors of weathered surfaces in the desert?

quartz
alkali feldspar
iron oxides
all of these


Approximately what percentage of the world's deserts are covered with sand?

5%
20%
50%
100%


A wadi is a ________

shallow lake
playa with salt sediments
dry wash
flood deposits


A mesa is __________

flood deposit in a small dry wash
a flat plateau surrounded by steep cliffs
mountain showing horizontal sedimentary layering
a pediment with an alluvial fan cover

Return to the Physical Geology Home Page