Unit 1: The Earth's Internal Dynamics, Ies La Flota Notes

UNIT 1

AF RICA SOUTH AMERICA

THE EARTH'S INTERNAL DYNAMICS

BIOLOGY AND GEOLOGY. 4º ESO. BRITISH COUNCIL. IES LA FLOTALA FLOTA INSTITUTO IES La Flota Dpto Ciencias Naturales Biology and Geology 4º ESO

UNIT 1: THE EARTH'S INTERNAL DYNAMICS

1. INTRODUCTION

1.1. THE EARTH'S FOUR SPHERES 1.2. THE EARTH'S COMPONENTS: MINERALS AND ROCKS 1.3. METHODS TO STUDY THE INSIDE OF THE EARTH

2. THE EARTH'S INTERNAL STRUCTURE

2.1. GEOCHEMICAL MODEL 2.2. DYNAMIC MODEL

3. ARE CONTINENTS MOVING?

3.1. CONTINENTAL DRIFT THEORY 3.2. SEAFLOOR SPREADING

4. PLATE TECTONICS

4.1. LITHOSPHERIC PLATES 4.2. PLATE BOUNDARIES 4.3. CAUSES OF PLATE MOVEMENT

KEY WORDS

• Geosphere
• Crust
• Mwstle C
• Core
• Lithosphere
• Mesosphere
• Endosphere Astenosphere
• Minerals
• Metamorphic rocks : getonorpbicsrocks
• Sedimentary rocks
• Seismic waves Des ciondi mualves
• Drift
• Palaeontology Palajepjdo&gy
• To move apart
• To move sideways To move socheways move towards
• Tectonic/ lithospheric plate
• Transform boundary : Fossfeud boundary
• Divergent boundary
• To rub : Earthquakes
• Oceanic ridges
• To sink : To erdsh
• Subduction Convection currents Convection currents fognaation currents

BIBLIOGRAPHY AND WEBGRAPHY

• Different text books (Oxford Editorial, ANAYA, McGraw- Hill, ByME, Richmond, Edelvives ... )
• https://www.bbc.co.uk/bitesize
• https://sciencehelpdesk.com/
• https://ssec.si.edu/
• https://www.nationalgeographic.org
• https://www.geolsoc.org.uk
• Study.com
• Youtube ...

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• To fold (up)
• Plate boundary : EstvagEM Boundary Rocks laneous rocks Discontinuity To displaceLA FLOTA IES La Flota Dpto Ciencias Naturales INSTITUTO Biology and Geology 3º ESO English Bilingual Program

1. INTRODUCTION

Watch the following video and enjoy! https://www.youtube.com/watch?v=Q6gjIkF4OFQ

1.1. THE EARTH'S FOUR SPHERES

FOUR SPHERES GEOSPHERE ATMOSPHERE HYDROSPHERE BIOSPHERE

1.2. THE EARTH'S COMPONENTS: MINERALS AND ROCKS

Watch carefully the next VIDEO and answer the questions: https://www.youtube.com/watch?v=FVW9CBI52nU until minute 1:28

1. What is the difference between a rock and a mineral?
2. How do we benefit from rocks and minerals? Give two examples of how we do or do not benefit from rocks and minerals.
3. How do humans get the rocks out of the ground for use?

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Watch the VIDEOS to get more information about the origin of minerals and rocks: https://www.youtube.com/watch?v=XEg_XuCMD2s (Rocks and minerals. EarthScience WesternAustralia) https://www.youtube.com/watch?v=uAAeFB7Tv5A (Rock Cycle. Dan Pérez) https://www.youtube.com/watch?v=Vp_S3BDiR-I (Rock Cycle. Learning made fun)

Use this page to create a big diagram with the three main types of rocks, the way they are formed, their types and some examples:

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THE ROCK CYCLE

The rock cycle is a concept used to explain how the three basic rock types are related and how Earth processes, over geologic time, change a rock from one type into another. Plate tectonic activity, along with weathering and erosional processes, are responsible for the continued recycling of rocks.

Rocks are classified into three basic types based on how they are formed.

• Igneous - A rock formed by the cooling and crystallization of magma (molten rock) at or below the Earth's surface.
• Sedimentary - A rock formed as a result of the weathering process, either by compaction and cementation of rock mineral fragments, or the precipitation of dissolved minerals.
• Metamorphic - These rocks form as existing rocks are subjected to intense heat and/or pressure, usually over long periods of time.

The rocks in display are meant to be viewed in a clockwise direction. As you walk, keep in mind that existing rocks may change through natural processes over geologic time, or event melt to form new rocks.

compaction & cementation Sedimentary Rock sediments weathering & erosion weathering & erosion weathering & erosion heat & pressure Igneous Rock heat & pressure Metamorphic Rock melting cooling melting magma

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The Rock Cycle

Erosion & Transport Weathering of ROCKS at surface Deposition of SEDIMENT 1 Burial & Compaction IGNEOUS ROCK Uplift SEDIMENTARY ROCK Crystallisation of MAGMA METAMORPHIC ROCK Deformation & Metamorphism Melting Activity 1: On the rock cycle below, color arrows orange if they indicate a process leading to formation of igneous rocks, Brown if they indicate a process leading to formation of sedimentary rocks and green if they indicate a process leading to formation of metamorphic rocks.

Compaction, cementation (Lithification) Sedimentary rocks Sediment Heat, intense pressure (Metamorphism) Uplift, erosion, weathering Metamorphic rocks Igneous rocks Melting Cooling Crystallization Magma

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Activity 2: Rock Group Characteristics

Place check marks in the table to indicate what rock group(s) is/are characterized by each of the processes and rock properties.

Processes and Rock properties Igneous Sedimentary Metamorphic Intense heating (but no melting) Solidification of magma /lava Melting of rock Compaction of sediment Cementation of grains Folding of rock Common fossils Foliated Crystalline

1.3. METHODS TO STUDY THE INSIDE OF THE EARTH

Scientists use different methods to get to know the Earth's interior, Read carefully and create a diagram:

DIRECT METHODS

Materials emerging from inside the Earth Analysing volcanic and plutonic materials on the surface, which come from several kilometres below the surface, as well as inclusions (rocks brought up to the surface with rising magma). Boreholes and prospecting Drilling down from the surface creates research boreholes, and a column of material, known as a core sample, is extracted. This allows researchers to study rock composition directly. Data from deep mines Extracting and studying rocks and minerals from deeper than three kilometres. Analysis of meteorites Some meteorites have a similar composition to the layers inside the Earth.

INDIRECT METHODS

Magnetic method Studying anomalies in the Earth's magnetic field, using a magnetometer .. This method is very old but very effective in explaining plate tectonics. Gravimetric method Studying fluctuations in the gravitational field in different parts of the planet. Gravity is lower the higher up you are, because you are further from the centre of the Earth. It also varies according to the composition of the rock. Geothermal method Studying the gradual reduction in heat, called geothermal gradient, from the Earth's core toward the surface. Seismic method Studying the difference in speed and changes in direction of seismic waves as they pass through layers of the Earth with different properties. This is the method that has provided the most data about the Earth's composition and internal structure. Electric method Studying the conductivity of rocks. This method is also used to locate water underground and to esta- blish the depth of metal deposits.

4 To know more: Kola Superdeep Borehole: https://www.youtube.com/watch?v=zz6v6OfoQvs&t=89s

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4 To know more: Seismic waves: Watch the video and answer the questions: https://www.youtube.com/watch?v=7c-m0-FICio&t=468s

SEISMIC WAVES

1. What is the average thickness of the Crust?
2. Why have all the efforts to drill the crust been forced to stop?
3. What are indirect observations or methods? Give examples.
4. What are the body waves? Why are they so important to geologists?
5. Fill in the table about the main body waves:

P WAVES S WAVES It stands for ... Related to ... Speed Type of waves Particles move They can pass through

1. What happens when a P wave passes through a molten region?
2. What happens when a S wave passes through a molten region?
3. What is a discontinuity?

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1. Make a list of the main discontinuities, include their deepness, the layers of the Earth that they separate and the scientist who discovered them.

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2. THE EARTH'S INTERNAL STRUCTURE

Despite several ambitious projects to dig all the way through the Earth's crust, it has never been done. However, that hasn't prevented scientists from researching and learning about the internal structure and composition of the Earth.

FACTS ABOUT EARTH'S INTERIOR

The Earth's interior is at high temperature There is a direct relationship between depth (below the surface) and temperature. Volcanoes show us that the material inside the Earth can reach very high temperatures. The Earth's interior is extremely dense The inner layers of the Earth are very dense. In fact, the deeper the layer is, the greater the density. The Earth's interior is made up of high density rock, like iron (7.9 g/cm3) and nickel (8.9 g/cm3). The Earth has its own magnetic field The metallic core of the Earth creates a magnetic field and the resulting magnetic North and South poles, like a magnet. When a compass points North, its metallic elements are being attracted to the South end of the Earth's magnetic field.

GEOCHEMICAL MODEL

The study of seismic waves has allowed scientists to determine that the interior of the Earth is divided into layers and that there are discontinuities (or boundaries) between these layers. Thus, according to a chemical composition criteria, these layers are crust, mantle and core.

continental crust oceanic crust Mohorovicic discontinuity Crust. It is the thinnest outer layer of the Earth. It has an average thickness of 35 km under the continents (continental crust) and 8 km under the ocean (oceanic crust). It is comprised mostly of granite, gneiss and basalt. Mantle. This middle layer is also the thickest one (up to 2,900 km), of Earth. It is mostly solid but is liquid in some areas. Its most common mineral is peridotite. Gutenberg discontinuity outer core Lehman discontinuity inner core Core. It is the Earth's innermost layer. It is comprised of nickel and iron.

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