1. structure and composition of the geosphere

The Earth’s internal dynamics

© McGraw-Hill Education

Biology and Geology 4. Unit 8. The Earth’s internal dynamics

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Worksheet – Student B

1. Structure and composition of the

geosphere

1. Classify the features in the cloud.

Methods for studying the geosphere

Direct Indirect

2. Work with your partner to fill in the missing information.




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3. Identify and correct the false statements.

Geochemical or static model

It explains the Earth’s structure by splitting it into concentric layers according to their

density. __

The core is the deepest layer which is made up of iron and nickel and is where the Earth’s

magnetic force is created. __

The outer core is in a solid state whereas the inner core is liquid. __

The Earth’s magnetic field is due to the outer core’s convection currents. __

The mantle is the rocky, thin, solid outer layer which is divided into the upper and the lower

mantle. __

The lower mantle, denser than the upper one, is highly compacted due to the high pressure

exerted by the layers above it. __

The continental crust consists mainly of olivine and peridotite, and its thickness is constant. __

The oceanic crust, made of basalt and gabbro, forms the ocean floors. __

4. Put the blocks of text in the correct order.

Seismic discontinuity

The transition zones – are known as - with different properties – between two layers - seismic

discontinuities

_____________________________________________________________________________

They are called seismic discontinuities – they change velocity and direction - cross them to pass

through matter - with different properties, - because when seismic waves

_____________________________________________________________________________

This phenomenon, - is called refraction - which all waves undergo,

_____________________________________________________________________________




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5. Fill in the gaps in the text using the terms below it. ______ refers to the fact that the Earth ______ like a perfect

spherical ______, although it is fact an ______.

This property determines the ______ that make up geological

processes such as ______ arcs produced by the ______ of

tectonic plates, or the constant ______ of Earth’s ______.

Movement - Sphericity - Island - Ellipsoid - Behaves - Trajectory - Dynamics - Shape - Orbit

______ is the state of ______ in the Earth’s surface produced by

variations in ______ at different points. Based on Archimedes’

______, it causes vertical, or ______, movements because the

______ parts of the crust tend to ______ and the ______ parts

tend to ______. Isostasy is a key factor in creating the ______ of

the Earth’s surface. This elevation process is followed by a process

of ______ and wearing down, resulting in the isostatic ______

that maintains the planet’s sphericity.

equilibrium - epirogenic - balance - sink - contours - isostasy - denser - lighter - principle - rise - density - erosion

6. Circle the correct option.

The Earth acts as a giant/small magnet. This force comes from

conduction/convection currents in the inner/outer core.

Earth’s magnetic field extends beyond the

exosphere/mesosphere and attracts charged particles in the

solar wind which do not enter Earth’s

magnetosphere/ionosphere. This helps allow the development

of life in our planet.

Earth’s gravitational/electric field is produced by the planet’s

charge/mass, according to Newton’s/Archimedes’ law of

universal gravitation. It attracts all nearby masses towards its

crust/centre and its internal structure is organised into layers,

according to their relative chemical composition/density. It

also governs geological processes, the atmosphere and

biosphere/hydrosphere and the development of life.

7. Correct the 7 spelling mistakes. The geodinamic modell divides the insid of the Earth into seberal zones, on the bases of two

criteria: their phisycal estate and their behaviour or dynamic.




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8. Complete the diagram.

9. Answer the multiple choice questions.

Geothermal gradient

Geothermal gradient is the continuous increase in temperature in the Earth in relation to…

a) Decreasing depth.

b) Varying layers’ composition.

c) Increasing depth.

Dynamics in the different layers of the Earth result from…

a) The movement of the tectonic plates.

b) The heat flowing from the centre of the planet to the surface.

c) The Earth’s magnetic field.

The heat transported from the outer core comprises…

a) Residual heat from the planet’s formation.

b) Heat as a result of thermonuclear reactions in its radioactive components.

c) a) and b).




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2. Internal geodynamics 10. Listen and fill in the gaps in the text.

Internal geodynamics is the study of the Earth’s internal ______, their behaviour and their ______

for geological phenomena and ______, including mountain formation, ______ and volcanicity.

______ theories explain the formation of orogens and the ______ of the land.

______ theories were formulated during the 19th and early 20th centuries. They base their

explanation of the ______ of mountains and geological ______ on the assumption that the ______

have always been in the ______ position that they are ______ in.

Fixist theories propose that Earth’s continents have ______ the same geographical ______

throughout history.

These theories were ______ by the arguments of ______ theories. Information ______ in the

1960s from ocean ______ and using the seismic ______ supported mobilist theory, as explained in

the ______ model of the Earth’s internal structure.

11. Identify the false statements and correct them.

Mobilist theories propose that the continents have always been in the same position that

they are currently in. __

Alfred Wegener was an early proponent of the idea that the geosphere is a dynamic system. __

Convection currents do not take part in the movement of the continents. __

According to the continental drift theory, the lithosphere is divided into several plates which

are in constant movement in relation to one another. __

The discovery of ocean ridges and seafloor spreading confirmed the hypothesis of convection

currents as responsible for the continents’ movement. __

Pangaea was a supercontinent formed by today’s continents. __




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12. Solve the cryptogram. Then work with your partner to fill in the missing information in the figure.

Continental drift theory

Evidence

Assumptions




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3. Seafloor spreading

13. Fill in the gaps in the text using the terms below it.

In 1960, geologist Harry Hess proposed that matter ______ up from the ______ along oceanic

______ creates new crust.

______ spreading theory states that new ______ is formed at the oceanic ridges when new

material rises and is ______ to the sides of the ridge, thus increasing the ______ of the ocean

floor.

At an oceanic ridge, ______ pushes ______ to either side, separating it and raising the ______ of

the ridge. Rock on either ______ of a ridge has the same ______ orientation and forms ______

parallel bands.

level - crust - pressure - symmetrical - rising -pushed - mantle - magnetic - magma - ridges - area - side - seafloor


Evidence for seafloor spreading

1) Age of gabbro/basalt rocks

The older/younger the rocks of

the ocean ridges/floors are, the

closer/further they lie from

oceanic ridges and the

closer/further they lie to the

continents.

2) Palaeomagnetism

The Earth’s magnetic

field is stable/unstable,

and its polarity has

inverted from time to

time in the course of

history. These changes in

polarity are

recorded/collected in

rocks that contain the

mineral

olivine/magnetite,

which, as it solidifies,

orients itself according to

the Earth’s magnetic

field.

3) Presence of sediment on

ocean floors

Sediment is not distributed

evenly on the ocean floor:

there is no sediment/

sediment along ocean ridges.

The amount and density/size

of sediment increases away

from the ridges/continents

and towards the

ridges/continents. This

shows that the ocean floor

moves and slowly accumulates

sediment over time.




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4. Plate tectonics 15. Listen and fill in the gaps in the text.

Plate tectonics theory ______ the lithosphere into lithospheric ______ which are in ______

movement.

It is based on the following ______ principles:

Lithospheric plates move because of ______ in the Earth’s ______.

The lithosphere is made up of the ______ and the ______ mantle, which form a dynamic

______, broken up into lithospheric or tectonic plates.

Convection affects the whole mantle, so its movement ______ with it the part of the

lithosphere ______ on it.

The ______ that supports plate tectonics is:

1. ______ of seismically active ______: These are areas with ______ levels of geological

______, including volcanoes and ______. The Circum-Pacific Belt and the Eurasian-

Melanesian Belt both measure ______ of kilometres and are marked by ______ and faults.

2. ______ of oceanic ______: They coincide with areas of high geological activity. This activity

maintains the ______ of the Earth’s crust by ______ it at convergent boundaries and

creating it at ______ boundaries.

16. Complete the diagram.




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17. Complete the table.

Types of plate boundaries Plate

boundaries Diagram

Characteristic

relief

Associated

phenomena Examples

Divergent or

constructive

Convergent or

destructive

Transform or conservative




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5. Consequences of the Earth’s internal

dynamics

18. Solve the cryptogram.

19. Solve the crossword.

Across 2. They are formed when continental plates separate, resulting in the crust

sinking. 4. The underground point where the earthquake's focus lies. 6. Waves that occur on the surface, causing horizontal movements from one side to the other. 8. It occurs when continental plates

collide, creating folds and deposits. 9. The spread of vibrations through matter which are emitted by a seismic movement. Seismic movements are the result of elastic energy accumulated in the Earth's crust being released.

10. The point on the ground directly

above the earthquake's focus. 11. Body waves that pass through all matter, solid or liquid. Down

1. Surface waves whose movement is elliptical. 3. Body waves that pass through solid matter. 5. They form when oceanic plates separate and break the ocean floor. 7. Sudden movements of the Earth's

surface. They occur in unstable parts of the crust and, in particular, at plate boundaries.




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20. Listen and fill in the gaps in the text.

Measurements of earthquakes

______ measures the elastic ______ released in an earthquake. It is calculated by measuring the ______ registered by a ______ located at

least 100 km from the ______. It is measured using the ______ scale, which assigns a ______ from 2 to 10 according to the ______ of energy released.

______ measures the ______ of land movement and the ______ of vibration recorded in a particular ______. It is measured using the ______ intensity scale, which has 12 ______, from I to XII.

A ______ is an instrument used to record ______ movement, and its

results are displayed on a ______. P waves arrive ______ as they spread ______, followed by the S waves. They are both ______ waves. The ______ waves arrive last: they come from the ______, and they are the most ______, because they cause ______ to the Earth’s surface.


Seismic waves: a way of studying the Earth’s interior

The seismic method means studying the outside/inside of the

Earth by applying our knowledge of the properties of seismic

waves.

P and S waves vary in velocity/intensity and direction when

they go through layers with different properties or

chemical/physical states, giving rise to shadow/dark zones.

These changes help us work out the location/depth at which

the Earth’s properties change, as sharp/smooth changes

coincide with seismic continuities/discontinuities. We can

also use this method to work out the general properties of the

lithosphere’s/geosphere’s internal layers.

22. Fill in the gaps in the text using the terms below it.

Volcanism and volcanoes

A ______ is a geological ______ on the Earth’s surface. It is a ______ through which matter from inside the

Earth, known as ______, rises and is released.

Volcanoes are located in ______ active parts of the planet, such as new ______ranges, oceanic ______, ______ zones and so-called ‘______ spots’. In other words, they are ______ to lithospheric plate ______. They release matter to the Earth’s surface during volcanic ______.

eruptions - seismically - magma - mountain - subduction - volcano - boundaries - linked - fissure - hot - structure - ridges




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23. Match the information and label the picture.

Structure of a volcano Crater Seismic zone Cone Bedrock

Magma chamber Ash cloud Solidified lava Secondary cone Vent

Channel through which magma rises during an eruption

Large underground pool of molten rock and gases called magma

It is caused by the eruption It is built up in layers Secondary cone-shaped formation around the

crater Exit point Truncated cone-shaped formation around the

crater, built up by the accumulation of lava from

previous eruptions It is made up of particles that fall around the

volcano. Layer of solid rock beneath the surface of the

Earth




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24. Complete the flow chart.

6. The Wilson cycle 25. Work with your partner to fill in the missing information.

1. structure and composition of the geosphere

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