THE WORK OF WIND AND
DESERTS
INTRODUCTION
• WIND is an effective agent of erosion and
transportation in desert regions
• Running WATER accounts for most erosion
I. WIND TRANSPORT
• 1. Bed load
• Sediments too large or
heavy (saltation)
• 2. Suspended load
• Silt- and clay-sized particles
II. WIND EROSION
• Wind is an efficient
sorter of sediment
1. ABRASION
• Etching, polishing, and
pitting are some of the
effects
• Ventifacts are stones with
shape modified by
abrasion
2. DEFLATION
• The removal of loose
surface sediment by wind
erosion creates blowouts
• Desert pavement
III. WIND DEPOSITS
• 1. DUNES occur in several distinctive types,
consist of sand, and are deposited near their
source
1. DUNES
• form when an object on the surface slows the wind so
that deposition takes place
2. DUNE TYPES
• A. Barchan dunes
• crescent-shaped
• tips point downwind
• form on flat, dry
surfaces with little
vegetation, limited sand
supply
• the most mobile dune -
up to 10m/yr
• White Sands
2. DUNE TYPES
• B. Longitudinal or seif dunes
• long, parallel ridges of sand
• aligned generally parallel to wind
direction
• can be up to 100m high
• Australia, Saudi Arabia, and Egypt
2. DUNE TYPES
• C. Transverse dunes
• form long ridges
perpendicular to the
prevailing wind
direction
• abundant sand supply
• crests up to 200m high
• White Sands
2. DUNE TYPES
• D. Parabolic dunes
• common in coastal areas
• abundant sand supply
• strong onshore wind
• tips point upwind,
anchored by vegetation
2. D UN E TYPES
• E. Star dunes
• common in Saudi Arabia
• pyramidal hills of sand
• several ridges radiate from
the crest
• form where wind direction
is variable
• stable dunes, many are
landmarks for desert
travelers
WHITE SANDS
• Tularosa Basin
• Gypsum
• 275 square miles
(world’s largest field)
3. LOESS
• Windblown silt and clay deposits, far from their source
• Soils on loess deposits are some of the most fertile in the
world
IV. DISTRIBUTION OF AIR-PRESSURE BELTS AND
GLOBAL WIND PATTERNS
V. DESERTS
• Where evaporation
exceeds precipitation
• 1. the low to middle
latitudes, associated with
high-pressure belts
• 2. some found in the deep
interiors of continents
• 3. others are rainshadow
deserts
V. DESERTS
• 1. temperatures vary
greatly - extreme highs
and lows
• 2. receive less than 25cm
of precipitation/year
• 3. plants are diverse, yet
widely spaced, small, and
slow-growing
V. DESERTS
• Weathering and Soils
• 4. mechanical weathering is
dominant due to temperature
fluctuations and frost wedging
• rock varnish coats many rocks
with iron and manganese oxides
• 5. soils are thin and patchy
CHIHUAHUAN DESERT
800 miles long and 250 miles wide
* New Mexico, and Texas and the cities of El
Paso and Las Cruces in the United States, as
well as parts of the states of Chihuahua,
Coahuila, Nuevo Leon, Durango, Zacatecas, and
San Luis Potosi and the cities of Juarez, Cd.
Chihuahua, Torreon, and Saltillo in Mexico.
BASIN AND RANGE
VI. DESERTS LANDFORMS
• 1. Alluvial Fans
• form when
sediment-laden
streams flow out
from mountain
fronts into the flat
desert floor
• may coalesce to
form a bajada
VI. DESERT LANDFORMS
• 2. Playa (Lake)
• results from the
evaporation of a playa
lake, leaving a salt pan
• characterized by mud
cracks and salt crystals
• Salt Flat Basin
SALT FLAT BASIN
Guadalupe Mts
SALT WAR (1860’S)
VI. DESERT LANDFORMS
• 3. Pediments
• erosional bedrock
surfaces
• 4. Inselberg
• resistant, projecting high
in deserts
• 5. Mesas and Buttes
• steep sided, flat topped
