Most deserts have angular landscapes due to mechanical weathering with little soil or vegetation. Softer, more rounded forms occur where deposition dominates, like dunes. Desert rainfall is unpredictable and can cause flash flooding and intense erosion. Common desert landforms include sand deserts, pavement plains, arroyos, inselbergs, and playas formed by water and wind erosion. Arid regions also experience yardangs, ventifacts, and dunes due to eolian processes.

1. ARID LANDFORMS

2. BASIC CONCEPTS
I. Most deserts exhibit highly angular landscapes.
• mechanical weathering dominates
• little soil or vegetation to soften landscape
II. Softer, more rounded landscapes appear where
deposition is predominant.
• dunes
III. Desert rainfall is infrequent, intense, and unreliable.
• intense flash flooding,
• intense erosion
• ephemeral streams

5. Death Valley, July 15, 1999

6. Las Vegas Flash Flood

7. TYPES OF DESERTS
1-Sand Deserts
•Largest are in Sahara and Arabian Deserts,
•Sand covers about 20% of world’s deserts
• Vegetation rare

8. TYPES OF DESERTS
2-Pavement of pebbles and stones
• all small materials and sand removed by wind
• may be very thin coating of stones

9. A gibber plain in Australia
Desert pavement

10. DESERT LANDSCAPE (FEATURES)
 Weathering and desert streams create Desert features
 Weathering (Mechanical & Chemical)
 is mostly mechanical
 little chemical weathering produces manganese and
iron-oxide stains, called desert vanish
 Stream Erosion
 Arroyo- channel with water during periods of high discharge
but dry most part of the year
 Pediments- large-scale gently inclined surfaces
 Inselberg- steep-sided knob of durable rock
 Playa- dry lake bed

11. CHEMICAL WEATHERING

12. DESERT VANISH
Desert varnish
• oxidation of iron and manganese,
• useful for dating desert surfaces

13. DESERT FLUVIAL ROCESSES
Fluvial Erosion
• rare, intense flash floods.
• fluvial systems decrease in discharge downstream
• Landforms:
– Washes (Western US), dry streambed
– Wadis (Asia and Africa), dry streambed
– Arroyos (Spanish), dry streambed
– Canyons,
– alluvial fans,
– rock debris in piedmont region

14. DESERT FLUVIAL ROCESSES
 Fluvial Transportation
 large amounts of rock and sand moved short distances.
 Fluvial Deposition
 where water slows on flat playas material is deposited and
sorted by size.

15. DESERT LANDFORMS PRODUCED BY WATER

16. ARROYO

17. INSELBERG
Kata Tjuta (The Olgas), Australia Uluru (Ayers Rock) Inselberg,
Australia
Inselberg - “island mountains” rise out of desert landscapes

18. WATER-CARVED CANYON

19. Slot
Canyon

20. The
Narrows,
Zion N.P.,
Utah

21. AEOLIAN (WIND) PROCESSES/LAND FORMS
Aeolian Erosion - much less effective than fluvial
• deflation - the movement of small particles
• abrasion - polishes and etches exposed surfaces
Aeolian Transportation - moves nothing bigger than sand
• dust storms - can extend thousands of feet up
• sand storms - only very near the surface
Aeolian Deposition - dunes form and shift where winds and
terrain combine to slow the winds or block the movement of
dunes.

22. DEFLATION

23. DESERT PAVEMENTS (1)

24. DESERT PAVEMENTS (2)

25. DESERT PAVEMENTS (3)

26. DESERT PAVEMENTS
Source: Martin Miller

27. DESERT PAVEMENT SLOWS INFILTRATION
CAUSES FLASH FLOODS

28. WIND ABRASION
IN ADDITION TO
OCCASIONAL FLASH
FLOOD EROSION
Abrasion

29. VENTIFACTS
Wind-shaped stones with sharp-edge faces

30. VENTIFACTS

31. YARDANGS
Streamlined desert ridges
White Desert, Egypt (500km from Cairo)

32. TRANSPORT BY WIND
 Suspended Load- most consist of dust
 silt, clay, pollen, bacteria, salt crystals, etc.
 Bed Load- sediments moved along or near the ground
 Rolling or saltation- bed loads lifted off the ground
momentarily due to force of collision with other grains

33. TRANSPORT OF WIND-BORNE SEDIMENT
Suspended Load Transports Sahara sediment to Caribbean and Amazon Rain Forest

34. Dust Storm, Senegal
Sand Storm

35. DESERTIFICATION
 Desertification- invasion of desert conditions into
formerly non-desert areas
 Drought and overpopulation are main causes
 Signs
 Lowering of water table
 Marked reduction of water supply
 Increased salinity in water and soil
 Progressive destruction of native vegetation
 Accelerated soil erosion

36. UAE LANDFORMS
 Islands
 Palm Islan-Dubai (man-made)
 Bu Tinah Island (close to AD)
 Saadiyat Island

37. UAE LANDFORMS
 Mountains (Al Hajer Mountains)
 Hafeet
 Cave systems (Maqarat khdair hafee)
 Hot springs
 Jabal Gis (North RAK-1900m)
 highest mountain top in the UAE
 Al Fujairah- mountain area

38. UAE LANDFORMS
 Oasis
 Al Ain (7 Oasis)
 Liwa Oasis (South AD) in Rub Alkhali desert
o Wetlands
o Ras Al Khor
o Mangroves
o Wading birds
o Fish
Flamingo
Liwa oasis
Al Ain oasis

39. UAE LANDFORMS
 Wadies
 Wadi al Batha- Um Al-Qaiwain
 Wadi Bih-Rak
 Dubai Creek-Salt water inlet
 Wadi Shi- Sharjah
 Wadi Siji- Fujairah-RAK
 Wadi Ham- Fujairah
 Wadi Hatta- Dubai
 Wadi Wurayah- Fujairah
 High biodiversity (e.g. Arabian Leopard)

40. UAE LANDFORMS
 Canyons
 Grand canyon (Fujairah/RAK)