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80 Cards in this Set
- Front
- Back
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What is the term for erosion by impact of sand grains carried by wind, sandblasting
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Abrasion
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What is the term fro stones with surfaces eroded by wind abrasion?
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Ventifact
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What is the term for elongate and streamlined ridges formed by differential wind erosion?
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Yardang
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What is the term for the removal of loose surface material by wind?
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Deflation
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What is the term for surface of pebbles and larger stones left behind after wind removes smaller particles?
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Desert pavement
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What is the term for a ridge of sand size deposits?
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Dune
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What is the term for windblown silt and clay deposits?
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Loess
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What is the term for deflection of air currents due to EArth's rotations?
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Coriolis effect
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What is the term for a geographic area that receives less than 25 cm precipitation per year, also desert?
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Arid
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What is the term for a mountain range that blocks moisture from reaching the leeward side?
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RAinshadow
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What is the term for a dry lake bed or salt pan?
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Playa
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What is the term for a triangular deposit of river sediments adjacent to mountains
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Alluvial Fan
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What is the term a gently sloping bedrock surface formed by erosion?
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Pediment
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What is the term for the process of turning non-desert areas into deserts?
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Desertification
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What is the term for a broad, flat-topped erosional remnant landform with steep sides?
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Mesa
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What kind of load is silt and clay that is carried by the wind?
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Suspended Load
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How is salt carried by the wind?
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By SALTATION in the BED LOAD
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How do longitudinal dunes develop?
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When sand supply is limited, and
When winds converge |
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Which type of diversity, high or low, do desert plants show?
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HIGH DIVERSITY
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Name the 3 characteristics of desert plants:
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1. small
2. widely spaced 3. grow slowly |
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Is desert soil usually thick or thin?
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Desert soil is usually THIN.
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Is desert soil evenly dispersed?
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NO< It is in PATCHES
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T or F
Desert soil easily erodes because of the sparse vegetation. |
TRUE
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What type of erosion is deflation?
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Wind Erosion
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What is removed during deflation?
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Loose surface material
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What will a mesa form as it continues to erode?
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A Yardang
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What is the term for an isolated pillar-like landform?
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A Yardang
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What happens to pediments as the mountains adjacent to them are buried or eroded?
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Pediments get LARGER
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Name 4 areas where desertification is a major problem?
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1. Africa
2. Asia 3. Middle East 4. United States |
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How fast can Barchan dunes move?
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Rates over 10 meters per year
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Where do Barchan dunes form?
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Areas with
1. Little vegetation 2. Flat ground surface 3. Limited sand supply 4. Constant wind direction |
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How are dunes classified?
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1. Shape
2. Relation to wind direction into 4 major types |
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What are the 4 reasons why we study deserts:
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1. Large areas of the EArth are deserts
2. Global warming may cause desert regions to expand 3. Understand Mars better 4. Knowledge helps us predict the effects of future climate change |
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Name 4 landforms created by wind erosion:
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1. Yardang
2. Blowout 3. Ventifact 4. Desert pavement |
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T or F
Barchan is a landform created by wind erosion. |
FALSE
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Name 4 characteristics of dunes:
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1. form in different shapes depending on conditions
2. tend to migrate downwind 3. usually grow larger with time 4. can develop in deserts or beaches |
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What do coastal areas with lots of sand, strong onshore winds, and some vegetation?
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Parabolic dunes
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What types of dunes are among the tallest dunes in the world?
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Star Dunes
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What are 2 features of soils formed from loess?
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1. Very fertile
2. Found in the Great Plains of the US |
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Why do deserts form at @ 30 degress north and south latitudes?
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Atmosphere circulation causes dry air to descend there.
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What types of weathering are important in deserts?
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1. Frost wedging
2. Salt crystal growth 3. Root action 4. Daily temperature fluctuations |
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T or F
Hydrolysis is important in deserts. |
FALSE
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Describe how rock varnish develops?
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As a red, brown, or black shiny coating on rock surfaces
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Name 2 reasons why water erosion is a powerful force in deserts:
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1. Vegetation is sparse
2. Rainfall is often in powerful cloudbursts |
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T or F
Most streams in deserts flow intermittently. |
TRUE
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T or F
Most streams in deserts carry water rich in phosphates. |
FALSE
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T or F
Most streams in deserts were smaller in Pleistocene time |
FALSE
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T or F
Most streams in deserts are fed by groundwater. |
FALSE
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Where are the best places to drill for groundwater in deserts?
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BAjadas
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How do pediments probably form?
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Combination of:
1. erosion by sheetflow 2. erosion |
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Name 4 erosional landforms?
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1. Mesa
2. Butte 3. Inselberg 4. Pediment |
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T or F
A playa is an erosional landform |
FALSE
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How do people increase the amount of dust in the air as population expands in semi-arid and arid areas?
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1. Removing desert plants
2. Removing desert pavement 3. Exposing land to deflation |
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What type of landform is Uluru (Ayer's Rock) which is a steep sided mountain that stands all alone in the Australian desert?
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Inselberg
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Why do deserts have economic value?
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Playas are sources of salt and borates
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Name 4 ways humans cause desertification:
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1. Removal of natural vegetation
2. Overgrazing by livestock 3. Overuse of water 4. Overpopulation |
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How does wind move sand grains?
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Saltation
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T or F
Deflation can form shallow depressions. |
TRUE
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T or F
Deflation can form inselbergs several hundreds of km long? |
FALSE
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T or F
Deflation typically occurs where vegetation anchors rocks. |
FALSE
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T or F
Deflation is most common during couldbursts when erosion is intense. |
FALSE
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How is desertification accelerated?
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Grazing too many animals for the region
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Why can't wind transport particles over sand size?
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Wind has lower density
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Why have some layers of Hawaii yeilded much older dates if the volcanic island of Hawaii is less than 1 million years old?
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Layers contain windblown materials from Asia
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What rocks are mainly affected by wind abrasion?
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Rocks within 3 meters of the surface
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How are yardangs formed?
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Wind abrasion
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List 3 characteristics of desert pavement:
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1. forms mainly due to deflation
2. protects desert land from further erosion 3. is removed to prepare for construction thus increasing the dust in the air. |
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What are 4 characteristics of the fastest dunes:
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1. migrate at over 10 meters per year
2. include barchans 3. form in areas with little vegetation 4. are driven by winds from a nearly constant direction |
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How much precipitation do all deserts receive:
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Less than 25 centimeters annually
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How do desert plants adapt to dry conditions:
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1. grow slowly
2. reduce transportation with hard waxy leaves and stems 3. have widespread, shallow root systems 4. stay small |
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T or F
Running water is responsible for most erosional landforms in deserts. |
TRUE
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T or F
Sand seas are large areas covered by transverse dunes. |
TRUE
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T or F
Loess only forms in deserts where wind erosion is the dominant geologic process. |
FALSE
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T or F
Air currents race form zones of low-pressure to zones of high-pressure, thus increasing the air pressure. |
FALSE
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T or F
Mechanical weathering dominates in desert areas/ |
TRUE
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T or F
The groundwater table in deserts is higher under permanent streams. |
TRUE
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T or F
Desert pavement forms by wind transport and deposition of large pebbles. |
FALSE
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T or F
The type of dune formed depends on sand supply, wind directions and velocity , and amount of vegetation. |
TRUE
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T or F
Peteroglyphs were pecked into desert pavements. |
FALSE
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T or F
Dunes form when wind flows over and around an obstruction like a plant |
TRUE
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