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1、Unit3 Text Oceans of Sand Unit Three Oceans of Sand Desert Landscapes: sandy Desert Landscapes: stony Desert Landscapes World Deserts Background Information 纬度经度 There are three main causes of deserts. 1. The climate Patten of the world l Equatorial wind belts. 1. The climate Patten of the world Win
2、d blows away from the equator, air is too dry to form clouds. The Rainshadow effect Some deserts are in “rain shadow” area where the winds have lost what moisture they had crossing high ground. Land beyond the mountains receives no or little rain. Cold currents: The Upwelling Effect cools air passin
3、g over them, water fall before it reaches the land. 2 Human activities 3. The amount of animals Overgrazing by sheep and goats Too many trees cut down Food production No time for plants to recover Less plant cover soil exposed Soil eroded Desert Drought Wind Rain Sand dunes blown onto land How Deser
4、ts are made Adaptations to A Desert Biome 生物 群系 Desert Ecology 4. Where do small animals live in deserts? Why do they live there? lThey live in holes or burrows. lHoles or burrows trap moisture and stay cooler than the ground above. 浦乳动物 mammal mammal mammal Saguaro sidewinder sidewinder sidewinder
5、（美国西南部产的一种）响尾蛇 lizard lizard lizard 蜥蜴 （冷血的卵生）爬行动物 reptile reptile reptile reptile 沙砾 gravel gravel gravel Mud-brick houses Questions l1. What are the main characteristics of the desert? l2. where are the deserts located? l3. Why are the deserts hot during the day and cold at night? l4. How do plant
6、s survive in a hot desert? l5. The desert animals can survive, and why? l6. How do people survive in deserts? l7. what is probably the main cause of desertification? l8. What measures are taken by people to prevent the moving of deserts? Text learning The main characteristics of the desert?(para1-3)
7、 lAll deserts are dry, hot, sandy and barren; lClear skies and low rainfall; lUnpredictable weather. l1. Living in a desert climate (para4) lClear skies allow heat to escape into the atmosphere. l2. How plants survive (para5-7) lSeeds of dead plants-waiting for the next rain; lSome desert plants sto
8、re water in their deep roots, leaves and stems, some with fewer pores; lOther plants are protected by thorns or unpleasant taste. l3. Animal life (para8-11) lWhy did the animals shelter in the holes? lWhat is the function of the big ear for the mammals? lWhat is the “survival manual” of the reptiles
9、? l4. desert peoples (para12-14) lHow do they survive in deserts? lHunt animals and gather food plants; lGraze flocks of sheep and goats; lWear loose clothing and a veil to protect from sand and heat; lLive in oases and mud-brick houses with thick windowless walls. Text learning l5. on the move (par
10、a15-17) lThe main cause of Desertification: l The soil becomes exposed and eroded. lMeasures to prevent from Desertification: lPlanting trees lBuilding lines of stones across slopes to conserve soil and water. Text learning 1. Why are desert winds dry? Some deserts are in “rain shadow” area where th
11、e winds have lost what moisture they had crossing high ground. 2. Desert are very hot during the day, why are desert nights often cold? lDuring the day the sun is shining and no clouds in the sky to cover it . At night clear skies allow heat to escape into the atmosphere. 蒲公英 dandelion 3. How plants
12、 survive in deserts? saguaro mesquit(e) 墨西哥合欢树属植物；牧豆树 Some seeds of plants lie in the ground for years waiting for the rain. Other plants store water in their leaves, stems or roots. Many close their pores during the day so they do not lose moisture. 4. Where do small animals live in deserts? Why do
13、 they live there? lThey live in holes or burrows. lHoles or burrows trap moisture and stay cooler than the ground above. 5. Where do people live in some desert? around oases (fertile areas ) form around wells or springs 6. How do they survive in deserts? Hunt animals and gather food plants; Graze fl
14、ocks of sheep and goats; Wear loose clothing and a veil to protect from sand and heat; Live in oases and mud-brick houses with thick windowless walls. 6. How to prevent desertification 1. To plant trees and hedges(树篱：由一排密种的灌木或长得低的 树形成的一道栅栏或分界线) 2. To reduce the amount of animals to protect crops fro
15、m grazing. 3. To build lines of stones across slopes to prevent rainwater running away and allow it to soak into the soil. Tuareg of the Sahara A member of a Moslem, Berber- speaking people inhabiting the western and central Sahara and western Sahel of northwest Africa. 柏柏尔人：说柏柏尔语的穆斯林民族的 一支，居住在撒哈拉西部
16、和中部以及非 洲西北的西撒黑尔 Write down the words in blanks according to the meaning 1.Not good enough to produce crops. _ 2. That can not be predicted. _ 3. cruel, severe _ 4. Obtain by pressing, crushing, boiling etc._ 5. (of cattle, sheep, etc.) eat growing grass _ 6. Sharp-pointed growth on the stem of a plant _ 7. suitably, justly _ 8.(of acids, rain, etc.) wear away, eat into _ 9. Member of a tribe that wan
