UNIT 6 : THE INTERNAL ENERGY OF THE EARTH
I.ES.ClaraCampoamor Dto. Ciencias de la Naturaleza Mª Eugenia Becerril Quintero
1. THE STRUCTURE OF THE EARTH The Earth is one of nine planets in our solar system. It was formed 4600 million years ago from matter which was created in the “Big Bang”. The outside of the Earth cooled to form a solid rock surface, but the Earth's interior remains extremely hot. The Earth is divided into four layers: The crust is a layer of solid rock which is between 5km and 90km thick . It is thinner under the sea and thicker on the continents. The mantle is a 299km layer of semi-solid rock. The temperature of the mantle is up to 500ºC. The mantle is hot enough to melt, but remains solid because of the high pressure. The outer core is made of liquid iron and nickel. It is 2100km thick. The temperature is over 5000ºC. The inner core is a solid ball of iron and nickel and its temperature is 5500ºC.
1. When was the Earth formed?. 2. When was the matter of the Earth formed? 3. Where does the internal energy of the Earth come from?
4. How thick is the Earth´s crust? 5. The temperature of the Earth's core is : a- 1200ºC
b- 5000ºC
c- 5500ºC
d- 8500ºC
6. What is the Earth's core made from? 7. Draw the structure of the Earth.
2. TECTONIC PLATES
The Earth's crust is broken into huge parts called tectonic plates. There are two types of plates:
Continental
Less dense
Cannot sink into the mantle
Forms land
Oceanic
More dense
Can sink into the mantle and be destroyed
Forms the sea bed
8. What are the two different types of plates? Define them.
9. Spain is on which plate ?
10. How many plates are there?
11. Name the biggest plates.
12. Write the name of some countries which are between two plates
13. Look for Haiti on the map. How many plates can you see next to this country?
3. MOVING CONTINENTS In the past, all the world's continental plates were joined together, forming a super-continent called Pangea. Two hundred millions years ago, the super-continent broke up into seperate continents and began to drift very slowly around the Earth's surface. If you look at a world map, you can see how the continents would fit together as a puzzle.
Other evidence for continental drift:
•
•
•
Identical fossils have been found in Africa and South America. Mountains in the USA and Europe were part of one large mountain chain. Rocks found in Britain were formed in desert conditions.
14. What was Pangea? 15. When did Pangea break up? 16. What's the meaning of continental drift? 17. Do plates move horizontally, vertically or both?
18.- What are the evidences of the continental drift?
19. Have a look at the future map of the Earth. What will happen to the continents?
4. HOW ARE TECTONIC PLATES ABLE TO MOVE? Tectonic plates only move a few centimetres a year. This is very slow, but over millions of years they can move around the world. The Earth's core is extremely hot
Heat from the core rises into the mantle
Convection currents in the mantle causes the semi-molten rock to move in a circular motion
Movements in the mantle drag the tectonic plates sideways The movement of the tectonic plates is responsible for earthquakes and volcanic eruptions.
20. True or false?
1. 2. 3. 4.
The Earth's continents were joined together Mountains in Europe and the USA were part of a large mountain chain. Britain was a desert. Tectonic plates are not moving around the world now .
21. What is the reason why the plates are moving?
22. What causes volcanic eruptions and earthquakes?
5. TECTONIC PLATE BOUNDARIES Plate boundaries are the places where the edges of two or more tectonic plates meet. There are four types of plate boundaries:
Constructive boundary
• • • •
Oceanic plates move apart. New crust is formed in sea bed Underwater volcanoes. Gentle earthquakes
Destructive boundary •Oceanic and continental plates move together. •The oceanic crust is pushed down into the mantle. •Ocean crust is melted and destroyed. •Explosive volcanoes.
•
Violent earthquakes.
Collision boundary
Continental plates move together Plates buckle and fold to form mountains Violent earthquakes Volcanic activity is rare.
• • • •
Conservative boundary
• • •
Tectonic plates move in different directions, or at different speeds. No volcano Violent earthquakes
23. Match : - Two plates move sideways past each other
- Constructive boundary
- Oceanic plates move apart.
-Destructive boundary
- Continental plates move together
- Collision boundary
- Oceanic and continental plates move together
- Conservative boundary
24. Cross out the incorrect word in the sentences below: a- A constructive plate boundary is where two plates are diverging/converging b- At destructive plate boundaries, oceanic/continental crust is melted and destroyed. c- Fold mountains are formed at conservative/collision plate boundaries. d- At conservative plate boundaries, the most dangerous hazard is earthquakes/volcanoes. e-A collision boundary occurs where two oceanic/continental plates are converging. 25- Give an example of the different types of plate boundary: a- Constructive b- Destructive c- Collision d- Conservative
26- Study the previous map which shows the location of major tectonic plates, earthquake zones and volcanic areas.
a- Spain is on which plate
b- Suggest two places where there are earthquakes.
c- In which areas are there volcanoes?
d- Where do you think mountains are forming?
e-Locate Japan in the map. What happens there?
GLOSSARY Boundary
/'baʊndri/
To break up Buckle Thin To cool Volcano Core
Tectonic Thick
/'bʌkəl/ /ku:l/ /vɑ:l'keɪnəʊ / /kɔ:r /
Collision boundary
/θɪk/
Conservative boundary Constructive boundary Crust
/krʌst/
Dangerous Destructive boundary To drift Earthquake Edge Gentle Hazard To join Layer
/dʒɔɪn/ /'leɪər /
Mantle To melt Next to Plate
/pleɪt/
To push To rise
/raɪz/
Semi-molten Sideways
/'saɪdweɪz/
To sink
/sɪŋk/
GLOSSARY Boundary To break up
/'baʊndri/
límite
dividir
Buckle
/'bʌkəl/
To cool
/ku:l/
Core
/kɔ:r /
Crust
/krʌst/
Thick Plegarse
deriva
Earthquake Edge
Thin Volcano
Dangerous To drift
Tectonic
borde
/θɪk/
grosor delgado
/vɑ:l'keɪnəʊ /
Gentle Hazard To join Layer
riesgo /dʒɔɪn/ /'leɪər /
Mantle To melt Next to Plate
/pleɪt/
placa
/raɪz/
elevar
To push To rise Semi-molten Sideways
/'saɪdweɪz/ de lado
To sink
/sɪŋk/
hundir