Deserts

Question 1

can desserts be hot or cold?

Answer 1

yes, they can

Question 2

what is a desert?

Answer 2

very arid
- no permanent stream flows
- very little vegetation
- very little rainfall

Question 3

what is difference between hot and cold deserts?

Answer 3

hot:
low lat
low elev
far oceans
cold:
high lat
high elev
near cold ocean currents

Question 4

what are the 5 types of deserts?

Answer 4

subtropical
rain-shadow
coastal
continental interior
polar

Question 5

explain how subtropical deserts are formed

Answer 5

atmospheric convection
solar energy evaporates water which rises as hot moist air and then cools and expands dropping rain on rainforests
air stripped of moisture goes to subtropics

Question 6

what is latitude of subtropics?

Answer 6

20 to 30 degrees N or S
air heats up and landscape dries out
think african deserts

Question 7

how are rainshadow deserts formed?

Answer 7

A rain shadow is a patch of land that has been forced to become a desert because mountain ranges blocked all plant-growing, rainy weather. On one side of the mountain, wet weather systems drop rain and snow. On the other side of the mountain—the rain shadow side—all that precipitation is blocked.

Question 8

how are coastal deserts formed?

Answer 8

Coastal deserts are dry because the waters that are next to them are cold. Cold air can hold very little water and as a result the air next to coastal deserts loses almost all its moisture as rain before it reaches the land.

Question 9

what are interior deserts?

Answer 9

very dry land far from ocean moisture. air loses moisture as it crosses continents

Question 10

what are polar deserts?

Answer 10

above 66 degrees latitude N or S. air circulation carries dry air to polar regions. so cold air can’t hold moisture. no rain in 2 million years

Question 11

what causes deserts to look the way they do?

Answer 11

erosion by water and wind
weathering
soil formation
deposition

Question 12

what is desert varnish?

Answer 12

dark surface coating on exposed surfaces or iron and manganese oxides.
formed by bacterial activity, dust and water

Question 13

describe desert soils

Answer 13

thin with poorly defined horizons
iron oxides produce vibrant colors

Question 14

how does water affect deserts?

Answer 14

lack of roots magnifies erosion and transport
torrential rains generate flash floods
dry stream channels (where water goes if it does rain)

Question 15

why are flash floods so destructive in deserts?

Answer 15

• lack of vegetation
• repelling nature of soils prevents water from soaking in
  more flash floods due to global warming

Question 16

what is surface load in wind erosion?

Answer 16

grains move in contact with land surface by wind

Question 17

what is saltation?

Answer 17

sand skips and bounces by grain impact

Question 18

what is suspended load?

Answer 18

sediment carried in the air

Question 19

what are lag deposits?

Answer 19

accumulations of coarse material left behind after finer grains are removed by wind. The coarse material is too heavy for the remaining erosion agents to move, and it can protect the underlying finer material from being transported.

Question 20

what is deflation?

Answer 20

lowering land surface vis erosions. concentrated wind erosion creates a blowout

Question 21

what is talus aprons accumulation?

Answer 21

blocks break off ledges and cliffs. debris tumbles down slope accumulates at base.

Question 22

ALLUVIAL FAN

Question 23

What are two types of sediment load?

Answer 23

surface load: coarser sand-sized particles
suspended load: finer-grained, silt sized dust

Question 24

what are bajadas?

Answer 24

alluvial fans coalesce along mountain front

Question 25

how do salt lakes/playas form?

Answer 25

desert lake evaporates leaving behind flat lake bed with dissolved solids and salts

Question 26

how are mesas formed?

Answer 26

cliff retreat in a plateau of flat-lying rocks
also causes buttes and chimneys

Question 27

how to rock layers and weathering determine appearances?

Answer 27

resistant layers form steep vertical cliffs
weak layers weather and form rubble-covered slopes

Question 28

name the types of nonhorizontal bedding producing elongated linear ridges

Answer 28

cuesta
hogback
inselberg

Question 29

what is an inselberg?

Answer 29

an isolated hill or mountain rising abruptly from a plain. come in different shapes

Question 30

how is desert pavement created?

Answer 30

mosaic-like arrangement of surface stones. originates by dust in between the stone. surface stones lifted and dust thickens beneath. often coated with desert varnish

Question 31

what is a pediment?

Answer 31

gently sloping, low-relief erosion surface in a desert that forms at the base of a receding mountain front

Question 32

what are stony plains?

Answer 32

gently sloping, gravelly alluvial fans

Question 33

what are sand dunes?

Answer 33

windblown accumulations of sand. enormous cross beds. sand carried by wind accumulates around an obstacle.
dune form depends in variation in wind and sediment supply (scarce or abundant)

Question 34

how does a dune grow and move over time?

Answer 34

sand saltates up windward side and tumbles down slip face. dune grows and begins to move downwind

Question 35

what is desertification?

Answer 35

aridification of nondesert areas. human activity worsens natural processes.

Question 36

what are negative consequences of dust storms?

Answer 36

cross entire ocean basins
carry diseased organisms
destroy land and homes