Chapter 15 -- Deserts and Stuff

Question 0

An area with less than ##cm (## inches)of annual precipitation.
_______ may be cold, temperate, or hot. All major continents have one type of desert or the other.
In desert regions the wind is an effective agent of ________ and _________ due to a lack of water.
Covers about ##% of the land on Earth.

Answer 0

Desert
Erosion and Transportation
25cm (10in)

Question 1

The expansion of deserts into formerly productive lands.
These expansions destroy croplands and rangelands.
Causes starvation forcing people from their homelands
Main causes are drought and overpopulation
Closely related to global warming

Answer 1

Desertification

Question 2

Signs of Desertification (6)

Answer 2

Lowering of water table
Marked reduction of water supply
Increased salinity in water and soil
Progressive destruction of native vegetation
Accelerated soil erosion
Death of cattle - water dependent - foods

Question 3

Material too large or heavy to be carried in suspension by water or wind.
Particles are moved along the surface by saltation, rolling, or sliding.

Answer 3

Bed Load

Question 4

Material that can be carried in suspension by water or wind.
Composed of silt and clay sized particles.
Can be carried for thousands of kilometers.

Answer 4

Suspended Load

Question 5

Wind erosion can be caused through

Answer 5

Abrasion or Deflation

Question 6

Is the impact of saltating sand grains on an object. Its effect is similar to sandblasting.

Answer 6

Abrasion

Question 7

Stones whose surfaces have been polished, pitted, grooved, or faceted by the wind.
They are a common artifact of abrasion.

Answer 7

Ventifacts

Question 8

Is the removal of loose surface material by wind.

Answer 8

Deflation

Question 9

Is left behind after wind has removed the finer grained material and it protects the underlying material from deflation.

Answer 9

Desert Pavement

Question 10

Occur in several distinctive types, consist of sand, and are deposited near their source and covers ##% of the land.
Mounds or ridges of wind deposited sand close to its source
Form when wind flows over and around the obstruction, resulting in the deposition of sand grains, which accumulate.

Answer 10

Dunes

10%

Question 11

Consists of windblown silt and clay deposits composed of angular quartz grains, feldspar, micas, and calcite often found far from their source and covers 10% of the earth’s land and 30% of the US
Sources: Deserts, Pleistocene glacial deposits, floodplains.
Erode easily
Weathers to a rich, fertile soil.

Answer 11

Loess

Question 12

Types of Sand Dunes

Crescent shaped dunes whose tips point downwind
Form in the areas that have a generally flat, dry surface with little vegetation, a limited sand supply, constant wind direction.
Most mobile dune, up to 10m/yr

Answer 12

Barchan Dune

Question 13

Types of Dunes

Long, parallel ridges of sand aligned generally parallel to the direction of the prevailing winds.
Form where the sand supply is somewhat limited.
Can be up to 100m high (common in Egypt and Australia)

Answer 13

Longitudinal Dunes

Question 14

Types of Dunes

Form long ridges perpendicular to the prevailing wind direction
Found in areas that have abundant sand and little to no vegetation.
Crest up to 200m high.

Answer 14

Transverse Dunes

Question 15

Types of Dunes

Common in coastal areas
Features: abundant sand, strong onshore winds, tips point upwind, anchored by vegetation, center is often blown out.

Answer 15

Parabolic Dunes

Question 16

Types of Dunes

Several ridges radiate from the crest.
Features: variable wind direction, stable dunes with which many are landmarks for desert travelers.

Answer 16

Star Dunes

Question 17

Warm air rises, cool air sinks
Low pressure systems are dominant at ___ altitudes, high pressure at _____
Descending atmosphere cells in between result in another high pressure system.
The _______ effect describes the deflection of winds in the hemispheres due to the rotation of the Earth.

Answer 17

Low Altitudes
Poles
The Coriolis Effect

Question 18

The majority of the world’s deserts are located between ## and ## degrees north and south latitudes.

Answer 18

20 and 30

Question 19

Mountain ranges may block the flow of moist marine air creating a “____ ______”
Many middle and high latitude deserts are located far from the coast.

Answer 19

Rain Shadow Effect

Question 20

Most Deserts are characterized by…(5)

Answer 20

Widely vary temperatures – extreme highs and lows
a sparse plant cover
little precipitation at less than 25cm/year
plants are diverse, yet widely spaced, small, and slow growing
leaves are usually hard and waxy

Question 21

\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_ is dominant, coupled with slow rates of \_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_\_, results in poorly developed soils.
\_\_\_\_ \_\_\_\_\_\_\_\_ (\_\_\_\_\_ \_\_\_\_\_\_\_) coats many rocks with iron and manganese oxides.

Answer 21

Mechanical Weathering
Chemical Weathering
Rock Varnish (Desert Varnish)

Question 22

________ _________ is a major agent of erosion in deserts

Answer 22

Running Water

Question 23

_____ is capable of producing a variety of distinctive erosional and depositional features.

Answer 23

Wind

Question 24

________ ___________ describes a desert stream that never reaches the sea, depositing its load within the desert.

Answer 24

Internal Drainage

Question 25

Elongated streamlined ridges that look like an overturned ship’s hull.

Answer 25

Yardang

Question 26

Desert Landforms

Results from the evaporation of temporary lakes.
Most shallow and have shifting boundaries.
Evaporates to form a playa.
Characterized by mud cracks and salt crystals
Salts are often concentrated enough to be mined commercially

Answer 26

Playa Lakes

Question 27

Desert Formation

Form when sediment laden streams flow out from mountain fronts into the flat desert floor.
Poorly sorted, fans out from the mouth of the stream
Similar in shape and origin to deltas
Coalescing ________ ____ form ________.

Answer 27

Alluvial Fans

Bajadas

Question 28

Desert Landforms

Erosional bedrock surfaces
Low relief
Slope gently away from mountain bases

Answer 28

Pediments

Question 29

Desert Landforms

Isolated, steep sided erosional remnants that rise above desert plains.

Answer 29

Inselbergs

Question 30

Flat topped, pillar like, erosional remnants with steep slopes

Answer 30

Buttes

Question 31

Flat topped, table like, erosional remnants with steep slopes

Answer 31

Mesas