1. VENTIFACT YARDANG ZEUGEN ROCK PEDESTAL
- Rocks lying on the desert floor that have been shaped by the wind (abrasion)
- They have sharp edges and smooth sides
- They may have more than one
smoothed edge if there is more
than one wind direction or they
get moved by the wind.
- Vertical rock strata (soft/hard) parallel to pr. wind
- 5 to 100m high
- Up to 1000m long
- Shaped by deflation and
wind abrasion
- Some undercutting may
occur depending on the
angle of the rock strata
VENTIFACT
YARDANG
soft
hard
- Large amounts of sand are removed by deflation leaving a hollow
- From 3m wide and 1m deep to several kms wide
and 100s of ms deep
- May form due to faults
in rocks
- May reach water table and
produce an oasis or salt lake
- Horizontal rock strata (soft/hard)
- 3 to 30m high
- Joints in resistant rock widened by weathering
- Abrasion cuts through resistant
rock and develops deep furrows
in softer rock underneath
- Undercutting (abrasion and
saltation)may occur like with
a rock pedestal
DEFLATION HOLLOW
ZEUGEN
- Sand is removed by deflation and carried away in suspension by the wind.
- Rocks are too large to be
moved so get left behind
- More and more sand is
removed until the surface
is covered by closely packed
rock fragments.
- Mushroom shaped rocks
- Abrasion undercuts a mass of
resistant rock.
- Less resistant layers will be eroded
faster
- The bottom is eroded more because
it may be softer rock
- Also abrasion is most effective
Up to a height of 1.5m from the ground
REG/DESERT PAVEMENT
ROCK PEDESTAL

2. Aeolian Erosion Fluvial Erosion Aeolian Deposition
Desert Landforms
Aeolian Erosion
Desert Landforms
Fluvial Erosion
- Large areas of sand in arid regions are called ERGS
- Barchan are a common type of dune resulting from wind deposition
- Crescent shaped with horns facing downwind; horns move faster because less sand to move
- Migrate up to 30m per year. Up to 30m high (but other dunes
vary from few mm to 1000m).
- Sand moved up windward slope by saltation and surface creep
- Eddying wind helps maintain steep
slopes on leeward slope
- Continual avalanches on leeward slope
- Coarsest grains are at the top
- Bottom of leeward slope has sand ripples p.127
- Form in sedimentary rock with horizontal bedding planes. Mesa becomes a butte when it is taller than it is wide.
- Lower slopes covered in scree from weathering and rockfall. Eroded by water. Good example of parallel retreat as the sides are eroded uniformly all over.
- May have a
resistant igneous
cap rock. Steep
slopes fall away to
a wadi or canyon.
BARCHAN DUNE
MESA, BUTTE, SPIRE
Spire
Desert Landforms
Aeolian Deposition
- Pediments are wide gently sloped regions
at the base of more steeply sloped desert
mountain ranges.
- Often there is little or no soil on top of
the bedrock
- May be hidden by a bajada or alluvial fan
- May be at the base of a Mesa/Butte
PEDIMENT

3. Fluvial Deposition Desert Landforms WADI BADLANDS INSELBERG SALT LAKE
- Rounded isolated hill
- Found in semi-arid regions as well as other climates
- Much debate about their formation
- Believed to be relic features
formed when rainfall was high
by deep chemical weathering
- Crystalline rock e.g. granite
Desert Landforms
Fluvial Deposition
INSELBERG
- Dry river channels carved out by
water erosion during flash floods/
ephemeral rivers.
- Vary from a few ms in length to
over 100km long
- Steep sided with broad flat bottom
- Thick sediment leads to braiding
- Patterns change after each flood
- Water collects in deflation hollows and rapidly evaporates due to high temperatures
- Capillary actions draws salts to the surface creating a thick crust, which cracks into
polygonal shapes
- Sodium chloride is the most
common salt. These salts may be
commercially exploited.
- Also known as Chotts or Playas
WADI
SALT LAKE
- Found in semi-arid environments.
- Soft and relatively impermeable rock is shaped by rapid runoff from heavy but irregular rainfall
- Landscape comprises both
erosional and depositional
landforms e.g. wadis, pipes,
arches, hoodoos, alluvial fans.
- A stream exits the foot of a mountain
meeting gentle lowland slopes
- Rapid energy loss leads to rapid
deposition.
Deposits spread out in a fan shape
- Material is graded with the coarsest
load deposited first
- Vary in size from a few ms to several
kms in length
BADLANDS
ALLUVIAL FAN