003 - Hot, arid environments

Syllabus Point

Explain (AO2) weathering and the processes involved in wind and water-formed features.

Explain (AO2) the occurrence of flash floods.

Photograph Taken by Ellena Mart

Key Terminology

• Explain
• Weathering
• Flash flood

Define the terms above by using the 'Command Term' posters in the classroom, your 'IB Geography Course Companion' text book by Nagle and Cooke and the useful links below:

Useful Links

• Geological Society Definition - Weathering
• Google Definition - Flash flood

Activity One - Processes

While deserts are generally dry precipitation does fall in these regions and the rainfall can be dramatic. As you know from studying the Freshwater unit water is a key cause of weathering and erosion. Wind or aeolian forces also create a number of the dramatic landscapes that can be found in deserts. Answer the following questions using the text book recommended below:

1. What is regolith?
2. Describe the process of insolation weathering also known as onion-skin weathering. Remember to discuss the different types; granular disintegration (minerals expanding), exfoliation (peeling) and block disintegration (jointed rock).
3. How does salt weathering occur?
4. Remind yourselves how freeze-thaw occurs. Write a short description of the process.
5. What forms of chemical weathering take place in a desert?
6. Describe the processes of deflation, corrasion and attrition. Hopefully at least two of these words should be familiar from the Freshwater unit.
7. Draw a fully annotated diagram to show aeolian transportation. Remember to include the words suspension, saltation and creep. There is an image below that will also help you.
8. Why does aeolian deposition take place?
9. While water is scarce in deserts when it does rain why can processes created be powerful?

Useful Resources

• Dry Regions - The geology of deserts
• 'Arid Environments' text book by Cole pages 34-44

Image One - Transportation by Wind

Activity Two - Landforms created by wind

Aeolian Landforms

As you watch the youtube clip below answer the following questions:

1. Does water or wind create more change in a desert?
2. What is sand made up of?
3. Describe what a sand dune is and how it is formed (you may also need to use the text book to help you with this).
4. What factors does a sand dune depend on for its development?
5. What is a barchan sand dune? How does it form?
6. What is a star dune?
7. What is a linear dune and how is if formed?
8. What is a yardang?
9. What is a ventifact?
10. What is desert pavement?

Now you have watched the youtube clip you will need to 'flesh out' what landforms are created by wind in a desert, what they look like and how they are formed. The list below are the landforms you should focus on:

• Desert Pavements
• Rock Pedestals or mushroom rocks
• Zeugen
• Yardang
• Barchan or Crescent sand dune
• Linear dunes

Useful Resources

• For images - geogalot
• Desert Landforms Created by Wind
• 'Arid Environments' text book by Cole pages 49-57

Activity Three - Landforms created by water

Image Two - Erosional Landforms

Create a guide to landforms found in deserts created by water. You need to make sure you have an annotated diagram of each landform, describe what it looks like and also explain how they are formed. The landforms you need to focus on are:

• Wadis
• Canyons
• Mesa, Butte, Spire
• Inselbergs
• Alluvial fan
• Playas or salt lakes

Useful Resources

• Pdf - Desert Landforms
• 'Arid Environments' text book by Cole pages 59-69

Activity Four - 360 VR - Identify

Using the roundme.com app on your phones search for the Western Desert of Egypt. Using the different 360 degree images identify as many of the landforms you have described and explained above.

Activity Five - Flash Floods

Flash flooding has an amazing source of energy to change the landscape it is flowing through. Watch the clip below and describe what you see.

The main focus for this syllabus point is the occurrence of flash floods. Why do they happen? What conditions are needed for the flooding to occur?

1. What are the causes of flash floods in desert regions?
2. Read the article below and make notes on why flash floods are a relevant natural hazard for geographers to study.

Useful Resources

• Chicago Tribune - Utah floods that killed 19...

Exam Style Question

Explain why flash floods occur in hot desert regions. (4 marks)

Draw a fully annotated diagram to show the development of a desert landform. (4 marks)