Deserts

A desert may form along a coastline because a ________.

cold current cools and dries the air

A salt-rich flat lake bed in called a

playa.

Areas with relatively scarce sand and constantly shifting winds will develop ________ dunes.

star

Conversion of productive land to desert is known as ________.

desertification

Fine-grained sediments such as dust and silt can stay in the air and be transported by wind as ________.

suspended load

Isolated mountains that stick up above large expanses of desert alluvium are called

inselbergs

Most of the erosion in desert environments is caused by ________.

surface water

Over time, alluvial fans may merge to form a ________.

bajada

Much of the land area north of the Arctic Circle is considered to be a desert because

it is extremely arid.

The petroglyph in the image below is carved into _______, revealing the lighter-colored bedrock underneath.

desert varnish

can desert be cold

yes

are antartica and greenland deserts

yes

—Material that is too large or heavy to be carried in suspension by water or wind

—Particles move along the surface by saltation (bouncing), rolling, or sliding

bed load

—Material that can be carried in suspension by water or wind

—Composed of small (silt- and clay-sized) particles

—Can be carried thousands of kilometers

suspended load

—Material is ______ by wind either through abrasion or deflation

eroded

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

abrasion

—are rocks whose surfaces have been polished, pitted, grooved, or faceted by the wind abrasion

Ventifacts

is the removal of loose surface material by wind

deflation

are common features of deserts resulting from differential erosion by deflation

desert pavement and deflation hollows

a series of geoglyphs in the desert pavement of Peru created between 500BC and 500AD

Nazca lines

wind erosion is

slow

Mix of slow-growing bacteria, lichen, fungi, and mosses.

soil crust

Grow slowly, but cover much of the surface in deserts.

One footprint breaking through can take decades, centuries to recover

soil crust

mounds or ridges of wind-deposited sand

dunes

Most dunes have an ______- profile

asymmetric

crescent-shaped dunes whose tips point downwind

Barchan dunes

long, parallel ridges of sand aligned generally parallel to the direction of the prevailing winds, which alternate

Longitudinal dunes

long, parallel ridges of sand aligned generally perpendicular to the direction of the prevailing winds

Transverse dunes

– common in coastal areas

parabolic dune

huge pyramidal hills of sand

star dune

wind-blown silt and clay deposits composed of angular quartz grains, feldspar, micas, and calcite

Loess

in desert ______ weathering is the dominate form

mechanical

the thin red (Fe) to black (Mn) coating found on exposed rock surfaces in arid regions caused by oxidation.

desert varnish

almost exponential slope coming out of mountains

•Grows as an alluvial fan/Bajada reaches an equilibrium and begins to erode back into the mountains.

pediments

—Isolated, steep-sided erosional remnants that rise above desert plains

inselbergs

flat-topped erosional remnants with steep slopes

buttes and mesas

— receive more precipitation, yet they are moderately dry and support grasslands.

semiarid

—generally described as deserts, are dry and receive less than 25 cm of rain per year (very little vegetation, if any).

arid

The winds are deflected _______ in the northern hemisphere

clockwise

The winds are deflected _________ in the southern hemisphere

counter clockwise

—The winds are deflected as the earth rotates due to the

Coriolis effect

mountain ranges block the flow of moist marine air creating a

rain shadow

barchan dunes

bajadas

longitudinal dunes

mesa

transvers dune

star dune

butte

inselberg

parabolic dunes