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1. What is the Earth made of?The structure of the EarthThe Earth is divided into layers: The crust is the surface layer. It is a thin, solid layer made of rock. The mantle is the intermediate layer. This layer is almost 85 % of the Earth's volume.

It includes magma, which is molten rock. The core is the deepest layer. The core is part solid and part liquid.The Earth's temperature increases with depth. The temperature in the core reaches about 4,500 "C.

The internal structure ofthe EarthUpper mantle: this layer ofthe Earth has a depth of 70 to70 0 km. It is below the crust.

Crust: this layer of theEarth has a depthof 20 t o 70 km under thecontinents, but only about10 km under the oceans.

Core: the core has adepth of 3,000 to over6,000 km.

Lower mantle: th is layerof the Earth has a depthof 70 0 to 3,000 km.

The Earth's crust ActivitiesThe Earth's crust has a solid part (continents),and a liquid part (oceans).The continents

1. Complete these sentences.a. The surface layer of the Earth is called

the_.b. The intermediate layer is called the _.c. The scientific word for molten rock is _ _ .d. The Earth's crust consists of __ and _.

Continents are large land masses, surroundedby oceans and seas. There are six continents.In order of size, they are Asia, America, Africa,Antarctica, Europe and Oceania.The oceansOceans are large masses of salt water.There are five oceans. In order of size,they are the Pacific, the Atlantic, the Indian,the Southern and the Arctic.

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2. What is the Earth's relief?The Earth's surface is not flat.There are different kinds of relief:Continental reliefo Mountains are high landforms with steep sides.The world's highest mountain range istheHimalayas in Asia.

o Valleys are areas of low land betweenmountains. Rivers flow through many valleys.o Plains are low, flatareas ofland. Large plainsare often found on the coasts, and are formedby large livers.

o Plateaus are large, raised plains. The highestplateaus are in Tibet in Asia, and in Boliviain South America.

o Basins are natural depressions, or low areasof land. Some are below sea level.

Coasta.1 reliefo A peninsula is an area of land surroundedby water on all sides except one.o An isthmus connects a peninsula toa continent.

o A cape is a pan of the coast which extendsinto the sea.

o A gulf isa large area of a sea or ocean partiallyenclosed by land. A bay is a small gulf.

o An island is an area of land surroundedby water on all sides.o A group ofislands is called an archipelago.Coasts can be flat and low-lying or high:o In flat coastal areas, there are many beaches.o In high coastal areas, there are many cliffs,which are steep rock formations.

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Oceanic reliefThe ocean floor is varied and irregular. Its relief issimilar to continental relief.Continental shelves are near coastlines. These shelves are vast plateaus which reach a depthof 150 metres. Continental slopes lead down to the deeper pan of oceans.Large mountain ranges, called ocean ridges, rise up to 3,000 m from the ocean floor.Some of the highest peaks rise above the surface and form islands, such as the Hawaiian Islands.Ocean trenches are large, deep depressions in the ocean floor.The deepest ocean trench is Challenger Deep (11,000 m) in the Pacific Ocean.

Activity1. Readthe definitions. Which terms do they

refer to?a. It isan areaof low land between

mountains.b. It is surrounded bywater onall sides

except for one.c. I t is the name given to a group

of islands.d. It isa steep rockformation onthe coast.

The different kindsof relief on Earth

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3. Why do landscapes change?Changes in reliefThe Earths relief changes continually over a long period oftime by: Erosion is the fragmentation and dissolution of rocks, soil and mud,which is transported by wind or water.

Sedimentation is the accumulation of sediment, such asmud, sandor eroded rocks.

The course o f a river

1 . W ate rf al l: a s ec ti on o f a r iv erw h er e t he w a te r f al ls v er ti ca ll y

2, C an yo n: a d eep ch an ne l w ithsteep wai ls

3. A ll uv ia l p la in : a f la t, f er ti le a re aw h er e t he r iv er d ep os it ssediment

4. D elta : a trian gu lar area a t t hem outh o f a riv erE stu ar y: th e p ar t o f a r iv erwhere it meet s t h e s ea

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Causes of erosionThe most important agents of erosion aretemperature, water, wind and human beings.Abrupt changes in temperature can break rocks.There is a great difference between daytime andnighttime temperatures in mountains and deserts.Water sometimes infiltrates through rocks.When it freezes, it expands, and the rocks break.Water acts constantly on the land: Solution: water dissolves some rocks,such as limestone, producing unusual cavesand landscapes.

Fluvial erosion:- Rivers travel fast down steep slopes.They erode materials, and create deep valleysand canyons.

- When the slopes are gentler, the water movesmore slowly It transports the eroded materials.

- When rivers arrive at the flatter lands whichare near the sea, they deposit sedimenton their banks. These areas are known asalluvial plains.

Marine erosion: waves and currents wear awaycoasts and create cliffs. Subsequently, the watertransports the sediment and deposits it. Thisprocess forms beaches.

Wind transports particles of sand or soil fromtheir original place and deposits them. Thisprocess explains the formation of sand dunes.Human beings are also responsible for changinglandscapes with our everyday activities, such asfarming, mining and deforestation.The construction of houses, roads, tunnelsand reservoirs also alters landscapes.

Activities1. Lookat the drawing ofa riverAnswer the questions.a. Inwhich partofthe riverdoes erosionoccur?b. Inwhich part ofthe riveris sediment deposited?2. Compare the three photos.Whathas caused erosion ineach case?

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4. How does relief shape our planet?Continental driftIn 1912, the German scientist Alfred Wegener developed a new theory called continental drift.According to his theory, there was only one continent, which broke up millions of years ago.This continent was called Pangaea. Look at the coasts ofWestern Africa and South America.We can see that they seem to match like an enormous jigsaw~f__ /~ ~~ Tethys Sea

225 mil lion years ago 135 mil lion years ago 65 mil lion years ago

Tectonic platesThe Earths crust is divided into different plates called tectonic plates. Theseplates are in continuous movement. They move slowly at a speed of twoto ten centimetres per year. Some plates move apart, while others collide. The Earth's surface often undulates where plates collide. Folds are created. The Earth's crust sometimes fractures if the surface where plates collideis extremely rigid. Faults are created, and blocks rise or sink

The collision of plates has produced many mountains.The Himalaya mountain range in Asia is still rising.Map of the tectonic plates of the world

,;"s' _. - _ " ,--_ ~ - e - -

EURASIAN PLATE

i~'1 ). "

A r ea s o f s ei sm ic a ct iv it y ~

ajama: : t o SOUTH AMt:RICAN

~ PLATEt;Corcovado

IAIA!. Importantvoicano

ANTARCTIC PLATE

todayFormation of a fold

Formation of a fau ltmountain

INDO-AUSTRALIAJ" PLATE

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5. What are volcanoes and earthquakes?The movement of tectonic plates can produce volcanoes and earthquakes.VolcanoesA volcano is an opening in the surface of the Earth through which very hotmaterial (magma) comes out. When magma comes out of a volcano, it is called lava.When a volcano erupts, it also ejects ash and gases.Volcanic cones are the result of lava accumulatingoutside the opening. Volcanic eruptions under thesea can form islands, such as the Canary Islands.Volcanoes are generally found on the edge oftectonic plates because this is the weakest partof the Earth's crust. Earthquakes, geysers and hotsprings are all found in the same areas as volcanoes.

1. Magma ispushed upby the Earth'sinternal forces.

2. It rises througha pipe.

EarthquakesEarthquakes are caused by plate tectonics. When two plates crash, there is a releaseof energy that makes the ground vibrate. This vibration is called an earthquake.The vibration can be very violent or almost unnoticeable.Small tremors can occur for other reasons, such as when volcanoes eruptor when the roof of an underground cave falls in.Earthquakes on the ocean floor can produce huge waves called tsunamis.

A volcanic eruption

Activities1. Look at the map and answer these quest ions.

a, Which plate is the Iberian Peninsula on?b. Which plate are the Canary Islands on?c. Where do earthquakes and volcanic act iv ity

occur most frequently?2. Look at the map of plate tectonics

Close the book. How many plates can you remember?

A tsunami

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ActivitiesISO "0 so 60" , . "

BaffinBay

"!!~~~ Cape Farewell

Iceland

V ancouver I sl and

Reading a relief map1. Look at t he map and the altitude

chart and answer the quest ions.a. What colour is used to show

mountains over 4,000 metreshigh?

b. What colour is genera lly usedfor plains?

c. What colour are depress ions?d. What is the usual altitude of

plateaus?e. Why are there two shades of

blue?

C ap e R ac e(Finist

ATLANTICcaMrY'i1Iln(

3,718Teidl':

OCEA N Cape Verde

PACIFIC

OCEAN

2. Look at the map and find:a. The highest mountain range

in the wor ldb. The highest mountain range

in the southern hemispherec. A peninsula in North Americad. A large plateau in Asiae. The deepest ocean t renchf. An archipelagog. A gulf Falkland tslllnds

Cape Hornss'll~e

, I.e 9' S co ti a S e aQ'

SouthGeor g ia I sl a nd

lmetresl

, A n t ar c t iC C i r c leAN i A R c TI CPEN INSULA

5

WeddellSea; : : : : : = = . : . l i ~ ' _ 0 '

L D e pr e ss io n ~Scale1,002 2,004

180" kilometres 150" 120" , . " 60- 30"