Quick viewing(Text Mode)

Deserts Formandthephysical That Createtheconditionsinwhich Focus Ontheclimaticextremes Living Indesertareas

effects ontheenvironment. ,canhavemarked as mining,orindirectlythrough directly throughactivitiessuch others forsurvival.Humanimpacts, animal dependingononlyafew delicate, witheachplantand landscape. Lifeissimplebut processes thatshapethedesert formandthephysical that createtheconditionsinwhich focus ontheclimaticextremes living indesertareas. character oftheindigenouspeople also giveaglimpseofthelifeand Gods MustBeCrazyandWalkabout backdrop. Somefilms,suchasThe movies usingthedesertastheir throughsomeofthemany environments tostudy. inhabitants makedesertsfascinating adaptations andingenuityofits important compound—water. The live withlittleofEarth’s most plants andanimalsofthedesert for tropicalrainforests,the that createtheconditionssuitable end oftheatmosphericmovements to theharshconditions.Atother impact islimitedbutwelladapted life strugglestoexist.Human Unlike rainforestsandcoralreefs, Deserts aresparseandextreme. Learning focus focus Chapter To studydeserts,studentswill Students cangetasenseofthe are freetodownload fornon-commercial, educationalpurposes. booklets and postersthatcanbeusedas stimulusmaterial.They regions oftheworld.The website alsofeaturesotherpresentations, on theenvironmentaland humanissuesfacingmanyofthedesert and .Thisshort filmshowssomegraphicimages have alookatthemultimedia presentationontheissueofdeserts unep.org/wed/2006/english/Information_Material/index.asp and United NationsEnvironmentProgrammewebsiteat http://www. the largenumbersofpeoplewholiveintheseareas. Lookupthe awareness oftheenvironmentalissuesfacingdesert regionsand Environment Day2006wasthereforededicatedto raising the the InternationalYear ofDesertsandDesertification. The year2006wasdesignatedbytheUnitedNations tobe ICT/Research skills GLOBAL ENVIRONMENTS have made to live in them. in live to made have people adaptations the and environments desert in processes geographical the study Geographers . except continent every on located is environment global This desert. semi‑arid or arid as classified is surface land Earth’s of third one Almost fauna. and flora adapted highly and vegetation scattered to leading evaporation, of levels high and precipitation little very have mystery. They and adventure of places as pictures motion and books in portrayed environments, spectacular but stark are Deserts 7 4.10 explains how geographical knowledge,geographical how explains 4.10 between interrelationships the describes 4.8 that processes geographical the describes 4.6 tools geographical of range a uses 4.4 forms graphic and written,oral of range a uses 4.3 geographical interprets and organises 4.2 information geographical gathers and identifies 4.1 student: A outcomes Syllabus Deserts citizenship informed to contribute to civics of knowledge with combine skills and understanding environments and people environments transform and form information geographical communicate to information • construct and interpret bar,interpret and construct column,climatic • and maximum calculate and identify • statistics and Graphs map sketch a construct • relief interpret and identify • determine to compass the of points the use • linear using map a on distances measure • a on features cultural and physical identify • longitude,and latitude using features locate • maps of types various use • Maps tools Geographical • design and create a multimedia presentation multimedia a create and design • information electronic interpret and collect • ICT oblique,between distinguish aerial,ground‑ • images photographic interpret and collect • drawing line a draw • Photographs and proportional graphs proportional and minimum,total,range, average and rank direction scale map references grid and area Sampleimagery satellite and photographs level pages drought xerophyte—a plantadaptedtolivinginthedesertor wadi—a stream orrivercourseinavalley ofadesert them sustainable—using resources inaway thatdoesnotdegrade butnotbetweenthem Capricorn subtropical—climates closetothe Tropics ofCancerand and notforsale subsistence—crops orfoodgrowntosatisfyacommunity that receives anaverage 250–500millimetres ofrain peryear semi-arid—the transition zonebetweendesertandgrassland salty duetosaltsmoving insoils salinisation—the processby which soilandwater become so often playa—a flatbasininthedesertthatiscovered in water every the surfaceandplantscangrow oasis—an area inthedesertwhere groundwater iscloseto seasons andtheavailability offood environment toarange oflocations, usuallyrelated tothe nomadic—a lifestylewhere peoplemove aroundan to vapour evaporation—the processby which water fromliquid turns another andwiththeenvironmentinwhich theylive ecosystem—a communityoforganisms interacting withone degradation acrossmore arable land desertification—the spread ofdesertlandsandland Earth’s surface atmospheric pressure—the weightoftheairon arid—dry, parched climateorland arable—land thatiscapableofgrowingcrops aeolian—processes todowiththewind Definitions Chapter 7Deserts 157 Chapter OCEAN

1 662°N Siberia Arctic 7.1 7.4 The global distribution of desert environments Circle

Focus 7.1 World deserts Kara Kum Syrian Gobi ATLANTIC OCEAN Answers to Desert Deserts are spread around the world. Taklimakan Great activities 1 Basin 232°N Tropic of They are found in all continents and their people Desert Sonoran Cancer Desert Mojave except Europe. The people who Libyan Rub’ al-Khali Desert Peruvian Knowledge 0° Desert Nubian PACIFIC OCEAN Desert Equator make their homes in these harsh Deserts cover about 30 per cent of Earth’s land surface Desert SOUTH 1 Deserts are environments that and their area is increasing. They cover parts of at least environments are equally diverse. AMERICA 40 countries. All deserts have low rainfall but they are 1 Atacama receive low rainfall. They can 232°S Tropic of Many of these groups have been the not all the same in appearance—there are different Desert INDIAN OCEAN Capricorn be cold or hot, but they are types of deserts. People have always lived in the desert N stuff of stories and legends, such as Desert Sturt Stony Desert environment and there are communities associated with always dry. the Navajo of the in Kalahari specific desert locations. Desert 2 Deserts cover 30 per cent of the the USA, the Mongols from the Gobi Earth’s land surface. 661°S Desert in Mongolia, and the Bedouin What are deserts? 2 SOUTHERN OCEAN Antarctic Circle 3 Typically, hot deserts are found from Saudi Arabia. In this unit, Deserts are environments that receive very low rainfall. Deserts can be hot or cold, but they are always dry. They Key Hot dry desert Rainshadow desert Monsoon desert Cold Ocean in latitudes 30°N and 30°S. students will identify the location 0 2000 4000 km support sparse and specialised vegetation and limited Mid-latitude desert Coastal desert Polar desert currents 4 The six main types of deserts of deserts around the world and populations of animals and people. are: learn of the communities that have A desert environment can be classified as: 7.5 Deserts (excluding polar lands), their people and area • hot, dry deserts or trade • extremely arid—where there might be no precipitation survived in each location. 7.1 A Berber woman Activities for years, for example the of Chile, of the Sahara Rank Name Location Communities Area wind deserts South America of people (× 1000 km2) Knowledge • mid-latitude or semi-arid • arid—where there is less than 250 millimetres of 1 Sahara North Africa Taureg, Berber, 9065 1 What is the definition of a desert? per year, for example the Sahara of northern Africa desert Nubian 2 How much of Earth’s land surface is covered by desert? • semi-arid—where there is between 250 and types of deserts • rainshadow deserts 2 Gobi Mongolia and Mongol 1295 3 Where are typical hot, dry deserts generally found? 500 millimetres of rain annually and usually in a There are six main types of deserts, as summarised in the • coastal deserts Vocabulary China 4 Name the six main types of deserts. distinct wet season, for example the Tanami Desert in table below. the Northern Territory, Australia. 3 Patagonia Argentina Mapuche 673 5 What is the largest desert in the world? Where is it located • monsoon deserts preview 7.3 Main types of desert environment and what communities of people live there? 4 Rub’ al-Khali Saudi Arabia Bedouin, 650 • polar deserts. Where are deserts Name Location Examples Qashquai Skills 5 The largest desert is the arid leeward located? Hot, dry desert or Close to or between Sahara, Simpson, 5 Kalahari Southern !Kung, San 582 6 Use an atlas and 7.3 to name 10 countries that contain Sahara, which is located trade wind desert 20º and 30ºN and Great Victoria, deserts. The world map in 7.4 shows the global distribution of Africa 20º and 30ºS Kalahari, Rub al-Khali in North Africa. Three Atacama Mojave deserts. Deserts are not restricted by latitude, longitude or 7 Refer to 7.4. Draw a column graph to show the area of the 6 Chihuahuan United States; Huichol 455 six largest deserts. communities of people live in height above sea level, but in general the typical hot, dry Mid-latitude or semi- Between 30º and 50º Sonoran, Gobi, Negev, Mexico global distribution rainshadow deserts are located between 20° and 30°N and between arid desert from the Equator Sinai, Patagonian, Application this desert: the Taureg, Berber 20° and 30°S due to global patterns of air circulation. Kara Kum 7 Great Victoria Australia Mandjindja 349 8 Refer to 7.3. Describe with reference to the map the and Nubian people. Gobi Sahara Rainshadow desert On the leeward side Peruvian, Taklimakan 8 Kara Kum Turkmenistan Turkmen 348 location of: 7.2 Deserts receive little rainfall and therefore of tall mountains a hot, dry deserts b mid-latitude deserts 9 Taklamakan China Khumpa 272 Kalahari vegetation is sparse. c polar deserts d rainshadow deserts. Skills Coastal desert Located close to seas Atacama, Namib, 10 Great Sandy Australia Kokatja 267 9 Refer to 7.4. Write down your observations of the 6 Students could include Egypt, or oceans with cold Great Sandy relationship between cold ocean currents and the location 11 Tanami Australia Warlpiri 184 currents of deserts. Libya, Algeria, Mali, Niger, 12 Gibson Australia Mardu 156 Monsoon desert Near the Tropics of Thar, Rajasthan, 10 Describe the appearance of the Berber woman in 7.1, Chad, Sudan and Eritrea in including clothing and headwear. Explain how these and (wet season in Capricorn or Cancer Tanami 13 Atacama Chile Atacamenos 140 North Africa, United States, summer) other personal objects could help survival in the desert 14 Mojave Unites States Navajo, Apache, 65 environment. China, Mongolia, Australia, Literacy Polar desert Polar lands Antarctica, Northern Paiute Siberia Surf Saudi Arabia, Peru, Chile, Students will have some 15 Namib Namibia Himba 34 Argentina, Namibia, Angola, understanding of the terms ‘arid’, Botswana, South Africa, ‘global distribution’, ‘leeward’ and 158 Geography Focus 1 Deserts 159 Turkmenistan, India. ‘rainshadow’, so have them create sentences using each term in its correct context. For the names 7 A diagrammatic answer is required. The d Rainshadow deserts are generally of the deserts, ask students to Sample pagesgraph must be drawn with a ruler, all axes located on the eastern sides of large write a sentence using the name must be labelled and the graph titled. mountain ranges. of the desert and the country and Surf activity 9 Because cold currents bring cold dense continent in which it is found. Have students research one desert outside Australia and answer the Application air with little moisture, deserts can questions below in a Word document that contains two web links to 8 a Hot, dry deserts are located close to or often be found near areas where cold useful websites. centred on the 30° parallel of latitude both currents move close to the coast. Key competencies a Where is the desert? north and south of the Equator. 10 Answers will vary, but could include heavy b Describe the landforms. b Mid-latitude deserts are located between covering of clothes to survive the cold nights Students use the key competencies c Collect climatic data for a town in the desert from http://www.world latitudes 30° and 50° north and south of and keep off the strong sunlight, lined face, to extract information from the climate.com. Present the data in table format. the Equator. clothes made from home spun cloth, simple tables to create graphs. Students d Research two plants and two animals that live in this desert and outline c Polar deserts are located in the high possessions that are easy to transport, level of with access to technology tools can how they are adapted to living in their environment. latitudes in Antarctica and North Siberia. self-sufficiency. use ICT skills to assist in graphing e Name a community that lives in the desert and describe its way of life. activities.

158 Geography Focus 1 Teacher’s Edition Chapter 7 Deserts 159 7.2 Activities Focus 7.2 The hottest and driest places on Earth are located in 7 Timbuktu: August, Processes in the the desert environment. Winds and dust storms are also Knowledge July, September, atmospheric processes that are characteristics of deserts. Atmospheric forces are the 1 What type of weather is associated with high pressure? June, May, October, strongest processes creating Temperature 2 Why are hot, dry deserts located in the subtropical regions April, March, between 20º–30ºN and 20º–30ºS? the dry conditions of the desert desert atmosphere The air temperature at the surface in hot deserts can February, January, 3 Why are the winds over deserts dry? environment. Wind shapes reach over 50°C in the daytime. There are large variations in temperature due to the lack of plants, cloud cover December, November The atmosphere is the air surrounding the Earth 4 Why are there large variations in temperature in deserts? the landscape and extremes of and moisture, which would normally trap heat near the Arica: June, July, August, extending up about 100 kilometres in the upper surface. The temperature can drop 30°C in a few hours. Skills temperature shape the way plants layer. Processes in the atmosphere can be important September, January, February, 5 Construct climatic graphs from the following data: and animals survive. The study of in determining the location of different types of March, April, May, October, environments. Specific atmospheric conditions occur 7.8 The graph 60° Timbuktu, Mali, 16°N 3°W deserts provides a good opportunity in the areas where deserts are located. shows day and November, December for students to practise using night temperatures 50° JFMAMJJASOND Sydney: April, June, March, for desert regions 40° geographical tools, such as reading What processes cause hot, Hot summer day ºC 20 23 26 30 33 33 32 30 30 29 25 21 May, February, July, January, compared to a hot 30° summer day and weather charts, a variety of maps, dry deserts? 20° mm 0.1 0.2 0.2 1 4 19 62 79 33 3 0 0 August, October, December, a cold winter day. photographs and statistical tables The circulation of air between the hot Equator and the 10° Hottest temperatures Cold winter day November, September cold Poles creates areas of different atmospheric pressure Arica, Chile, 18°S 70°W and graphs. are experienced 0° 8 a The countries surrounding

known as pressure belts. Low-pressure belts are found during the day, Sahara –10° JFMAMJJASOND near the Equator where the air is warmed by the sun, while the coldest Mojave the Red Sea are Saudi Great Sandy –20° Atacama forcing it to rise. The air cools and starts sinking as it temperatures are ºC 22 22 21 19 18 16 16 16 16 17 19 21 Arabia, Yemen, Egypt, moves towards the Poles. usually experienced –30° Temperature mm 0 0 0 0 0 0.3 0.2 0.1 0.1 0 0 0 at night. Gobi Eritrea and Sudan. When the air reaches the subtropical latitudes of about in °C(Celsius) 7.6 In summer, dust and sand from the Saharan and 25–30°N and 25–30°S it sinks, causing high air pressure b The Sahara and Arabian Arabian deserts form dust storms over the Red Sea. 6 Use the information in the tables above and the climatic Vocabulary on Earth’s surface. The sinking air is dry because the data for Sydney on page 138. Calculate the following for Deserts are in this region. moisture has already been released over the tropical each of Timbuktu, Arica and Sydney: rainforests at the Equator. High-pressure systems bring Precipitation c The dust storm is evidenced preview 7.7 The circulation of air around the globe creates areas a maximum temperature fine, calm and sunny conditions and very little rainfall— Deserts are defined by their lack of precipitation. The of high pressure near the Tropics, bringing fine, stable b minimum temperature by the colour, texture and the typical atmospheric conditions in deserts. desert environment has less than 500 millimetres of rain conditions and little rainfall. c total annual rainfall flow of the shading in the loess in a year. Extremely arid places can go for 12 months or aeolian more without precipitation. When rain does occur it is d average annual temperature. satellite image. usually a torrential downpour. (See unit 7.3.) circulation mirages 7 For each place above rank the months from highest to In the upper atmosphere warm, lowest rainfall with 1 being highest and 12 lowest. Application dry air moves towards the poles Winds shape the desert wind Most intense solar radiation 8 Refer to 7.6 and an atlas: high pressure Cooler air from poles cooling as it goes. Cooler air from poles Wind is the movement of air that is caused by the uneven a What are the countries that surround the Red Sea? 9 Both Arica and Timbuktu heating of the Earth’s surface. Generally winds will blow Dry Dry b What deserts are found in this region? are in desert locations in from areas of high air pressure towards areas of low air pressure until the two areas have the same air pressure. c How can you tell there is a dust storm in this image? lower latitudes than Sydney. Clouds form and Deserts that occur in subtropical regions experience high drop moisture Application This creates dry and warmer Cooler air Cooler air air pressure and are quite windy. sinks near the equator sinks 9 Using the climatic graphs you constructed in activity 5 conditions in their climate. ICT/Geographical skills Warm air rises creating low creating (keeps temperature creating Winds in the subtropical region are highly variable. In one suggest reasons for the differences in precipitation and pressure at Earth’s surface Sydney’s location in the high air moderate). . high air day they can range from a gentle breeze to violent gusts of temperature. at the equator. The graphs in Skills activity 5 can up to 300 kilometres per hour. The winds are mostly dry pressure pressure 10 Refer to 7.7 then write a paragraph explaining the weather temperate zone and close to the L L L L L be constructed by hand using a around around because they travel over thousands of kilometres of land, and pressure patterns experienced in deserts. ocean ensures a steady supply 20°N– 20°S– cold oceans or high mountain ranges. Aeolian processes ruler, from a template, or by using H Warm humid wet weather H 11 Use 7.8 to describe the difference in temperatures 30°N. H H 30°S. are the action of winds on landforms. (See unit 7.3.) of rainfall throughout the year. H H between the Gobi, Sahara and Australian deserts. Suggest software such as Excel. Dust and sand are moved by wind in the direction of reasons for this. 10 Deserts experience the dry air N S ° the prevailing wind. Silt-sized particles can be carried ° Students can use a table to Fine sunny 2 Fine sunny 1 that has travelled from the 2 1 as dust suspended in the air and look like a haze above Surf

conditions, low 23 conditions, low Equator 0° complete Skills activity 7, or, if they 23 Tropic of Tropic tropics and cooled enough to humidity Capricorn humidity the surface of the ground. When deposited these small have used Excel to create the graphs, of Cancer Tropic particles are known as loess. sink at around latitude 30°, they can use the Sort function found 160 Geography Focus 1 Deserts 161 creating stable high-pressure under Data in the menu bar. systems and generally fine, sunny conditions. 11 Compared to the Australian Answers to activitiesSample pages4 The large variations in temperature are due to a lack of plants, cloud desert, the reaches cover and moisture which normally trap heat near the surface. much lower temperatures due Knowledge Skills to its elevation and the Sahara Surf activity experiences much hotter 1 High-pressure systems are associated with 5 A diagrammatic answer is required. There may be some variation in conditions due to its lack of Have students collect calm, fine and sunny conditions with little the second graph due to the need to adjust the scale on Arica’s rainfall vegetation and its location climatic data for a town or city in a desert rainfall. because the amounts are so small. closer to the Equator. Australian other than in Australia from http://www. 2 Hot, dry deserts are located in the subtropics because the 6 deserts have moderate extremes worldclimate.com. Ask them to use a warm air over the Equator has had a chance to cool in Location Max. Min. Total annual rainfall Average annual temperature due to their location south of temp. (°C) temp. (°C) (mm) (°C) computer graphing program to construct the upper atmosphere before it begins to sink back to the the tropics and the level of a climatic graph. Detailed instructions surface of the Earth. Timbuktu 33 20 223 18.6 vegetation that exists in these for this task are on pages 132–3 of the 3 The winds over deserts are dry because the moisture is Arica 22 16 332 27.7 older and more stable regions. Teacher’s Edition. released over the Equator as convectional rain as it rises Sydney 22 12 1216 17.5 over the Equatorial regions.

160 Geography Focus 1 Teacher’s Edition Chapter 7 Deserts 161 7.3 Storms and flash flooding Aquifers Focus 7.3 Storms can drop a lot of water very quickly, so there is Groundwater flows under many deserts in layers of rock Key competencies/ICT very little time for it to infiltrate into the ground. The known as aquifers. Water enters the aquifer in areas of Processes water runs off immediately and higher rainfall and can flow underground for thousands Deserts are fascinating places to GeoGraphy stream channels that are normally of kilometres. In places this water flows close to the Using either the library, a supply study, not only because of what is Focus dry can flood suddenly. The water surface forming an oasis as shown in 7.11. Australia has of National Geographic magazines, drains so quickly and violently the largest natural underground storage of water—the there, but because of what is not in the hydrosphere More people drown in that it carries boulders and stones Great Artesian Basin—flowing under its deserts. a suitable video or DVD on desert there. In this unit, students will deserts than die of thirst! downstream, sometimes for landforms, or the Internet, invite several hundred kilometres. examine the lack of water with an 7.12 Relief rainfall can be rare in some deserts due students to develop a visual emphasis on understanding the and lithosphere Rivers to the rainshadow effect and cold ocean currents. vocabulary of the terms in the processes that enable water to find Evaporation in deserts is high and rivers do not flow Windward side Clouds cannot Leeward side Vocabulary preview. This will help often, but when they do they can carry large amounts of rise over its way into these environments. Warm, moist wind them complete the definitions and sediment. Some rivers, such as the Nile in Egypt, have mountain Dry air Students will also see that deserts The hydrosphere is all the water on Earth enough water to maintain the flow through the desert, and High rates of Warmer written descriptions in Application Desert are more than sand, as the different and the lithosphere describes the solid outer deposit sediment in the ocean. In hot deserts where rivers evaporation ocean activity 15 on the next page. shell of Earth including the crust and part dry up, they leave behind a wide, flattened hard river bed types of desert landforms are of the mantle. Processes in the hydrosphere Mountain Have pairs of students work on 7.9 Deserts are large areas of very low rainfall known as a wadi. Rainfall and lithosphere—along with those in the Prevailing range examined. and are sometimes covered by sand dunes. a class presentation using pictures atmosphere and biosphere—shape and Desert lakes wind transform environments, including deserts. they have photocopied or cut and Very little The characteristics of the hydrosphere and Lakes form in deserts if there is enough rainfall, the desert hydrosphere evaporation Rainshadow pasted, or that they have collected lithosphere are quite distinctive in deserts. groundwater flow (water flowing under the ground) or Deserts are places that experience very low levels of melting snow. They are generally shallow, temporary Cold ocean (no rain from the Internet and compiled makes it precipitation but the rain that does fall often occurs in and salty. When they dry up they leave a flat salt crust current over the into a slide show. storms. There are also other features of the hydrosphere or hardpan known as a playa. Examples are Lake Eyre in mountain) 7.10 Features of the desert landscape that are particular to the desert environment. Australia and Utah’s Great Salt Lake, which make good Desert Dry air Vocabulary runways and tracks for racing. 9 Wadi Playa lake therefore no rain Sand dunes preview 8 Badlands 5 Butte Dust storm 7 Pedestal rock 7.11 In some places the groundwater in aquifers flows close to the surface and creates a small damp area known as an oasis. 2 Longitudinal dune alluvial fans arch badlands barchan butte dunes GeoGraphy flash flooding Focus gibber plains The fastest land speed achieved in a motor vehicle hardpan occurred in the Black Rock 4 Mesa Desert in Nevada in the United States. The land hydrosphere speed record set was 1228 kilometres per hour. 1 Barchan dune lithosphere 6 Arch 3 Star dune Oasis mesa 162 Geography Focus 1 Deserts 163 oasis pedestal rocks playa Sample pages sediment Work, employment and enterprise yardangs Brainstorm in class, or have students list individually, the dangers that could threaten the safety and survival of humans working wadi and visiting desert areas. Collect anecdotes of people who have encountered problems due to the natural processes occurring in these environments. An example is the story of Aron Ralston found at www.thehardway.com/stories/survival.htm.

162 Geography Focus 1 Teacher’s Edition Chapter 7 Deserts 163 the desert lithosphere Rocks are blasted with loose sand particles, causing abrasion. Wind also deposits sand, forming features such Activities Mathematics skills/ There are also features of the desert lithosphere that are as sand sheets, ripples and dunes. distinctive. Desert landforms are shaped by wind. For example, Knowledge ICT Sand dunes Sturt’s Stony Desert in Australia continues to be formed 1 How does rain generally fall in deserts? by wind removing finer particles and leaving behind small 2 Why does most of the water run off quickly? Many people believe that deserts are made up entirely of rocks. Abrasion creates distinctive shapes in rocks. Wind- 3 What is a wadi? Surf activity Students need to follow three steps sand. In fact sand only covers about 20 per cent of deserts. sculpted landforms known as yardangs can be kilometres 4 How does an oasis form? to draw the pie graph in Skills Sand landforms include dunes, ripples or flat sand long and tens of metres high. As an extension of the other sheets. Dunes are not static, but travel in the direction of 5 What percentage of a desert is made up of sand? activity 13. First, they should use the prevailing wind. Some of the world’s fastest moving 7.14 Types of desert landforms 6 Explain how stony or gibber plains are formed. activities listed in this unit, have dunes are in the in Egypt, travelling up to the text to find the percentage 7 Explain why very little vegetation grows in desert soils. students use an image search to 100 metres in one year. Dunes have gentle upwind slopes Name of Number in Process of Description landform diagram 7.10 formation of deserts for each category. and steep downwind slopes known as slip faces. 8 What is the driest desert in the world and how low is its find photos or diagrams of types of Mesa 4 Water erosion Flat topped hills eroded average precipitation in parts? Second, they should convert each There are several types of sand dune formations that desert landforms from the Internet out of desert rocks 9 How high can some sand dunes reach? percentage into a slice of the circle depend on wind direction, as listed in 7.13. and make hyperlinks to them from Butte 5 Abrasion Columns of rock worn 10 Explain why a desert area in Arizona got its name of used for the graph (multiplying 7.13 Main types of desert sand dune away by desert sand ‘’. What factors contribute to the landscape a Word document. Arch 6 Abrasion by Rock arches colour? each by 3.6). Finally, they should Type of Number in Wind Description sand blasting draw a circle using a compass and dune diagram 7.10 direction 11 Name two indigenous groups of the Painted Desert and Pedestal 7 Abrasion by Rocks which have a one of their activities that attracts tourists. Barchan/ 1 Winds blow in These are the most mark in and label the slices using a rocks sand blasting mushroom structure crescent one direction common dune Skills Badlands 8 Erosion of Landscape of dry protractor. Longitudinal 2 Winds Linear dunes can be hills and gorges and ridges 12 Draw a line drawing of the oasis in 7.11. generally up to 160 kilometres For an ICT component, have mountains 13 Draw a pie graph showing the proportion of desert Application come from 2 long and form sets landforms made up of sand, stony plain and rocky students transfer step 2 to an Excel directions of parallel ridges Wadi 9 Sediment Flat plain-like area 14 Rainfall is low in desert areas deposit from between eroded landform. Hint: use the information in ‘The desert Star 3 Winds come Three or more arms spreadsheet and draw the graph river or stream landscapes lithosphere’ section. because the moisture content from many radiate from a high using the tools detailed on pages 7.15 An indigenous Navajo displaying handicrafts in Application of the air is severely reduced. directions centre in a star dune front of one of the spectacular desert rock formations 132–3 of the Teacher’s Edition by Soils that have been shaped by wind and water. The craft 14 Refer to 7.9 and 7.10 to explain why there is very little This happens for a number of colours reflect the colours of the Painted Desert, Arizona. rainfall in coastal, rainshadow and hot, dry deserts. clicking on Pie Graph instead of Stony plains Soils in deserts are generally high in minerals, but low reasons: 15 Draw up a table on a poster using the column headings in organic matter and nutrients. Many soils have distinct Line – Column Graph on 2 axes. Fifty per cent of deserts are plains—flat land—where fine listed below. List each of the nine types of desert • Rainshadow—the area salt layers including sodium chloride. Very little grows particles and sand have been removed, and gravels and The Painted Desert, Arizona landforms that are shown in 7.13 and 7.14. In the in desert soils because there are no clouds or shade to is located behind or on pebbles are left behind. Gibber plains are stony deserts illustration column draw a diagram of the landform by protect the ground surface. The soil surface can get very The Painted Desert stretches across most of the northern that form on clay soils where the soil expands when it referring to the features in 7.10. The first one has been the leeward side of large hot—up to 75°C. part of the state of Arizona in the United States, with its and shrinks when dry, pushing rocks to the surface. done for you. mountains as shown in 7.12. western end lying close to the Grand Canyon. It consists Geographical skills The clay is hard and compact so little vegetation grows 16 Use an atlas to locate the Painted Desert region. Draw a of bright red and layered rocks, hardened sand dunes and Moist air from the ocean on the plain. One of the best examples of a stony plain is sketch map of its area in relation to the state of Arizona, hills that famously turn into shades of purple, blue and For Application activity 15, found in the of Iraq. two other US states and the Colorado River. rises over the mountains and desert records red at sunset and sunrise—hence its name. Landforms students can transfer the include dunes, badlands, mesas and buttes and there is Landform Description of Illustration condenses, resulting in rain. Rock formations • The largest desert on Earth is the Sahara, which a large variety of desert flora and fauna including the landform information directly from the text. would cover the equivalent of almost the entire The now dry air continues Thirty per cent of desert lands are made of exposed rock, area of Australia. rattlesnake, coyote and saltbush. The desert is continually Barchan Crescent-shaped To get an idea of the forms that soil and river deposits such as alluvial fans and playas. Over changing as the actions of water and wind cause erosion. dune dune. The most over the mountain. • Rub’ al-Khali desert in Saudi Arabia contains thousands of years water and wind have carved the desert common type each of these landforms take, have the largest area of continuous sand in the world. The outstanding colours and layered rocks come from • Coastal influences—cold landscape. Soft layers of rock wear away more quickly than mud, sandstone and volcanic ash. Decaying plant and students carry out the task in the hard layers making strange and unusual shapes, such as the • The Atacama is the driest desert in the world currents cool the air averaging only 0.8 millimetres of rainfall in animal matter from 220 million years ago when a conifer Badlands of Death Valley, United States. above them, creating little Key competencies/ICT section on a year. A little extra moisture comes from the forest covered the area, as well as minerals, also cause the the previous page. Invite them to regular morning fog that rolls in from the sea, bright colours. evaporation and only little Desert landforms where it forms as warm air and is cooled by a use the images to generate sketches Aeolian processes are the action of winds on the cold ocean current. The Navajo and Hopi people have lived in the region moisture can be retained. as an alternative. Remind them to landforms. Winds erode, transport and deposit materials. • Sand dunes can reach heights of 300 metres. of the Painted Desert for at least 1000 years. Today the Therefore, as the air blows Navajo people use the red clay of the desert to make hand- Winds remove loose and fine-grained particles of soil and • Dust from the Sahara has been carried as far Surf made pottery to sell to tourists. Coal and petroleum is over the warm land any include the source of each image. sand, and wear down land surfaces with a grinding action. away as Germany and the United Kingdom. also mined. moisture evaporates and rain does not occur, creating the 164 Geography Focus 1 Deserts 165 desert dunes shown in 7.12. • Other hot, dry deserts are 4 An oasis forms when the groundwater, found 8 The Atacama Desert in Chile is the driest desert in the world formed when circulating Answers to activities in layers of rock called aquifers, flows close to with an average rainfall of 0.8 mm per year. air from the equator is dry Sample pages and cool after the cycle of the surface. 9 Sand dunes can reach heights of 300 metres. Knowledge 5 Sand covers only 20 per cent of desert areas. 10 The Painted Desert gets its name from the bright red and evaporation, condensation 1 When rain does fall in deserts it falls 6 Stony deserts form when the fine particles and layered rocks, hardened sand dunes and hills that turn purple, and heavy rainfall over the quickly with immediate runoff that often sand have been removed leaving only pebbles and blue and red at sunset and sunrise. The colours and layered rainforests. Travelling high floods the usually dry stream channels. gravel. Gibber deserts form when clay soils expand rocks come from mud, sandstone, minerals, volcanic ash and in the atmosphere, this air cools and falls, creating high 2 The runoff occurs quickly because a large volume of when wet and then compact and harden as they decayed plant and animal matter from 220 million years ago. pressure systems with little water falls, the ground is dry and hard, and there is no dry. Rocks within the soil are squeezed out to the 11 The Navajo and Hopi indigenous groups live in the Painted moisture within them. vegetation to slow down the runoff. surface in the process. Desert area. Their handicrafts help attract tourists to the area. 15 A diagrammatic answer is 3 A wadi is like a dry, flat lake that forms from the 7 Very little grows in desert soils because they are Skills required. sediment deposits of a river or stream when it floods often salty, they contain little organic matter and 16 A diagrammatic answer is then dries up. the lack of clouds enable direct sunlight to heat 12 A diagrammatic answer is required. Students should use the line them up to temperatures up to 75°C. drawing Skills Master on page 33 of the coursebook as a guide. required. Students should 13 A diagrammatic answer is required. include labels and a title.

164 Geography Focus 1 Teacher’s Edition Chapter 7 Deserts 165 7.4 insects animals Focus 7.4 Thousands of species of insects live in deserts. They feed There are very few large mammals that live in deserts Literacy Processes in on plants and other insects, and pollinate flowers after wet because most are not capable of storing enough water seasons to help them reproduce. They provide food for and withstanding heat. Deserts provide little shelter from The characters who survive in the spiders, scorpions, toads, lizards and small mammals. Some the sun and little food to eat. Small vertebrates such Have students find words in the desert are usually full of colour examples of desert insects are ants, termites and scorpions. as reptiles and mice, and other highly adapted fauna, Vocabulary preview that match the dominate in the desert ecosystem. and diversity. This seems true for the desert biosphere Some insects have symbiotic relationships where one following list. If they don’t know humans, other animals and plants. depends on the other, and vice versa. For example, Most desert animals are small and nocturnal, which the meaning of any of the terms, the yucca moth is very important to the yucca plant minimises moisture loss and heat gain. Many live in The adaptations that enable them The availability of water (hydrosphere), extreme because it helps pollinate it, and the yucca plant is the burrows and cracks throughout the day, and come out at encourage them to use the text or a to survive often make them unique temperatures (atmosphere) and the type of soil only place the moth will lay its eggs. Other insects have night to hunt. Others hibernate or become dormant during dictionary to find the information. (lithosphere) combine to determine the types of flora 7.16 The desert made adaptations to deserts, including moths that can go the driest times. Some examples are given in 7.18. and it is this that captivates the and fauna (biosphere) that live in deserts. They all scorpion eats without food for a long time. sleep observer. In this unit, students interact with each other to form the desert ecosystem. insects in the desert and in turn 7.18 Many animals have made specific adaptations to the desert environments in which they live. cactus will glimpse some of these living becomes food for Name Desert Photo Adaptations humps things as they look at the life in plants mammals, birds Bactrian Gobi • Fat, padded feet to prevent sinking into the sand Some plants do manage to grow in deserts, though they and reptiles. fauna the desert. (double-humped) • Very little sweat and moisture loss are generally small and scattered. Desert flora needs to be camel • Stores body fat in its humps, which it can live off for up to movement able to survive long periods of time without rain. Plants GeoGraphy Focus six months have made adaptations to tolerate and cope with little or camouflage • Nostrils and ears can be shut against the sand no moisture and extreme temperatures, as summarised The latitudes of 30ºS and 30ºN are known as the horse latitudes. This night • Eyelashes give protection from the sun, sand and dust in the table below. Drought-resistant plants are known is because the winds are weak and variable and there is little rainfall. • Woolly coat to keep warm on cold winter nights water as xerophytes. Sailors on wind-powered ships about 200 years ago often had to throw their horses overboard to conserve water at these latitudes. inactive 7.17 Many plants have made adaptations to live in the desert. sting Spadefoot toad Sonoran • Digs a hole when it is dry and covers itself Name Desert Photo Adaptations Vocabulary • Stays in the burrow until the next rain Saguaro cactus Sonoran • Spikes protect the cactus from animals biosphere—fauna • When it rains it breeds quickly and lays eggs • Shallow widespread root system collects water over • Eggs hatch quickly, become tadpoles and toads before the hydrosphere—water preview great distances waters dry up xerophytes—cactus • Fleshy stem stores water • No leaves, preventing water loss—the chlorophyll scorpions—sting Bactrain necessary for photosynthesis is in the stem nocturnal—night • Body shape expands when it rains biosphere hibernate—sleep Namib sand Namib • Side winding means only two parts of the body touch the dormant—inactive dormant Sturt’s Desert Pea Great Victoria • Survives in the form of seeds which grow when snake hot sand at one time there is rain • Gets its moisture from the animals it eats thorny devil—camouflage hibernate • Only survives a few weeks, during which time it • Can bury itself in the sand to keep cool Bactrain—humps flowers, produces seeds and dies side winding—movement hydrosphere • Red flowers for rapid pollination by insects nocturnal

scorpions Thorny devil Australian • Camouflage to blend in and can change colour according to Inara melon Namib • Seeds only germinate when the Namib receives rain deserts sunlight and surroundings side winding • Sends roots several metres down to the water table • False head to confuse predators • Branches are green and photosynthesise, replacing • Long, sticky tongue for catching ants the role of leaves and reducing water loss to thorny devil • Spiny skin for protection evaporation • Dew forms on skin, then grooves lead water to the mouth xerophytes • Inflates with air when threatened, making it hard to swallow • Digs a shallow cave to sit in during very hot days • Lays eggs underground to keep them at an even temperature

166 Geography Focus 1 Deserts 167 Sample pages

166 Geography Focus 1 Teacher’s Edition Chapter 7 Deserts 167

Top View