unit 3 earth’s internal structure

Unit 3

Earth’s Internal Structure

Table of Contents Introduction 3

Essential Questions 4

Review 4

Lesson 3.1: The Crust 5

Objectives Warm-up Learn about It Key Points Web Links Check Your Understanding Challenge Yourself

5 5 7

12 12 13 14

Lesson 3.2: The Mantle 15


15 15 17 19 20 21 22

Lesson 3.3: The Core 23


23 23 24 27 27 28 28

Lesson 3.4: Earth's Layers and Other Terrestrial Planets 29


29 29 30 33 34 34 35

Laboratory Activity 36

Performance Task 38

Self Check 39

Key Words 40

Wrap up 41

References 41

Copyright © 2018 Quipper Limited 2

Until today, only a very small portion of Earth is explored by humans. More than 95% of the bulk of the planet remained a mystery until the emergence of the study of waves produced during the planet’s ground shaking. Earth is divided into three layers: the rigid crust where living things live in, mantle which can be further divided into layers, liquid outer core, and a solid inner core. Inner planets or the Earth-like planets are also believed to have similar internal structures. What are the differences in Earth’s layers? How are Earth’s layers different from the layers of other terrestrial planets? In this unit, you will discover the in-depth characteristics and composition of Earth’s layers, and that of the other terrestrial planets.


At the end of this unit, you should be able to answer the following questions.

● What are the layers of Earth? ● How are the layers of Earth different from one another? ● What is the composition of each layer of Earth? ● Is Earth’s internal structure different from that of the other terrestrial

planets? ● What are the similarities and differences of Earth’s internal structure from

that of the other terrestrial planets?

● Terrestrial planets are rocky planets. These include Mercury, Venus, Earth, and Mars.

● Earth’s differentiation refers to the process of forming layers of the planet due to gravity and density differences of materials during its early formation. Heavy elements sank to the center while others floated near the surface.


Similar to a hard-boiled egg, Earth has its outermost shell called the crust. This layer of Earth is the thinnest, thus, it is the layer that is most explored by humans. With all the discoveries and scientific expeditions, what are the composition and prominent features of Earth’s crust?

Egg-ARTH Materials:

● hard-boiled chicken egg ● metal knife ● newspaper

Procedure:

1. Examine the texture of the shell of a hard-boiled chicken egg. 2. Slice the egg in half. Make sure not to crack the eggshell. Examine the

thickness of the shell relative to the thickness of the egg white and egg yolk. 3. Carefully remove the shell. Examine its hardness. Crack the shell into at least

two pieces and compare the thickness of each piece with another. 4. Set aside the halved egg on a newspaper.


Data and Results: Complete the given table below by filling in the unshaded cells.

Table 1. Observation of characteristics chicken egg layers.

Observed quality Egg shell Egg white Egg yolk

Texture

Thickness

Hardness

Elasticity

Outermost/ middle layer/ innermost

Comparable model to a layer of Earth

Guide Questions:

1. In terms of texture, is the eggshell smooth or rough? 2. In terms of hardness, is the eggshell rigid or elastic? 3. What can you say about the thickness of the shell compared to the other

parts of the egg? 4. Is the thickness of each piece of eggshell equal to each other? Are there

thicker or thinner pieces? 5. Do you think that the eggshell is an acceptable model for Earth’s crust? Why

or why not? 6. What are the similarities between Earth’s crust and an eggshell that you can

think off?


The crust is the outermost layer of the geosphere. It is made up mostly of solid rocks and minerals, and is enriched in silica and other components. It is extremely thin, compared to the other layers, and its thickness varies from 5 to around 80 km depending on where you are on the planet. Crust accounts to <1% of Earth’s total volume. The boundary between the two layers is called the Mohorovičić discontinuity.

The crust, together with the uppermost part of the mantle, make up the brittle lithosphere, which is broken up into major sections called tectonic plates. These plates are in constant motion relative to each other and bounded by tectonically active plate boundaries. These are irregularly shaped slabs of rock that float on top of the asthenosphere.

Fig. 1. Earth’s major tectonic plates.


Abundant Elements on Earth’s Crust The abundance of elements on the crust was studied using its rock. Oxygen, silicon, aluminum, and iron are the abundant elements found on Earth’s crust. Table 1 shows the other elements present.

Table 2. Elements in Earth’s crust.

Element Percentage

oxygen 46.60

silicon 27.72

aluminum 8.13

iron 5.00

calcium 3.63

sodium 2.83

potassium 2.59

magnesium 2.09

titanium 0.40

hydrogen 0.14

Oxygen The most abundant element in Earth’s crust is oxygen with an average abundance of 276 900 ppm (parts per million). Oxygen combines with silicates, carbonates, and phosphates in which it serves as a major elemental component. It has several purposes to society such as in industries, medicine, and commercial purposes.


Silicon Silicon, being the second most common element, exists as a compound in the mantle and crust. Silicon is found in sand, quartzite, mica, and talc. This element is usually utilized in the production of ceramics, glass, cosmetics, insecticides, and pharmaceutical products. Aluminum Aluminum comes third at 80 700 ppm. Like silicon, it exists as a compound in the crust. This element is extracted from its compounds commonly through the Bayer and Hall-Heroult processes. It is a lightweight metal used in making utensil foils and packaging materials. Aluminum is also used to manufacture automobile parts, rockets, and machinery. Iron Iron is extracted from iron ores such as hematite and magnetite. It exists in Earth’s crust with a composition of 50 500 ppm. It has many applications, one of which is for the production of steel.

Types of Earth’s Crust There are two types of crust: oceanic and continental. Oceanic crust is composed mostly of dark-colored mafic rocks. The density of oceanic crust ranges from 2.9 to 3.1 g/cm3. The dark color and relatively high density can be attributed to the elevated iron, magnesium, and calcium content of mafic rocks. The oceanic crust is thin with thickness varying from 5 to 18 km. Oceanic crust hosts feature such as volcanoes and canyons. It can be divided into three regions, namely: continental margins, ocean basins, and ridges. Continental margins separate continental crust from oceanic crust. These are prominent between oceanic and continental crust in passive margins. In active margins, the more prominent features are trenches and island arcs. Deep ocean basins are the areas found between the continental margins and ocean ridges. These are the areas where features such as seamounts and abyssal plains can be found. Lastly, ocean ridges are composed of newly formed oceanic crust which has


been uplifted and faulted. These 2 km-high mountain belts occur in the middle of the oceans and wrap around the globe.

Fig. 2. The oceanic crust and its features.

The age of oceanic crust is approximately 180,000 million years old or less. The map in Figure 3 shows the age of oceanic crust worldwide.

Fig. 3. Age of oceanic crust worldwide.

The second type of crust, the continental crust, is composed of many rock types. It’s major component is granodiorite, a light-colored igneous rock. The thickness of continental crust reaches up to 80 km in mountainous areas and has an average thickness of 30 km. The density of continental crust is lower compared to oceanic crust and may range from 2.6 to 2.9 g/cm3. It is relatively older than oceanic crust as


the rocks along trenches in oceans are continually recycled through the process of subduction. The oldest known grain found in the continental crust is about 4 billion years old. The continental crust has several features including mountain belts and cratons. Mountain belts are elevated regions composed of uplifted and deformed rocks. These were formed through orogeny or mountain building events which occurred in the past. Cratons are regions which have areas that are expansive and composed of complexly deformed Precambrian crystalline rocks called shields. Shields are covered with a thin layer of sedimentary rocks are called stable platforms.

Fig. 4. Mountain belts, shields, and stable platforms.

Formation of Earth’s crust The crust is formed through differentiation of Earth. Billions of years ago, during the early formation of Earth, the planet was merely a big sphere of molten rock. Upon cooling, lighter materials rose near the surface forming the crust. Conventional theory states that Earth’s crust was formed by volcanic activity. However, new theories were published later on. One of this new theory was Baker and Sofonio’s theory stating that some of the material settled onto Earth’s early surface from the steamy atmosphere during that time. Scientists believe that a planetoid plowed into Earth 4.5 billion years ago. This collision melted Earth and turned it into an ocean of magma. Baker believed that the dissolved minerals from the collision rose to the upper atmosphere and cooled off. The silicate materials were dissolved at the surface and start to separate and fall back to Earth that caused a silicate rain.


● The outermost layer of Earth is the crust. ○ Earth’s crust is the thinnest layer among its layers. ○ Its most abundant element is oxygen but other elements such as iron,

aluminum, and silicon are also present. ○ It can either be classified as oceanic or continental crust.

For further readings, you can check the following web links:

● Read the interior of Earth Robertson, Eugene C. 1966. ‘The Interior of the Earth An Elementary.’ https://pubs.usgs.gov/circ/1966/0532/report.pdf

● A video of Earth’s crust, volcano and plates User: Lisa Kelly. 2012. ‘Earth’s Crust.’ Video. https://www.youtube.com/watch?v=tWQwYQqd36A

● An informative interactive about a journey to the center of Earth BBC Future. N.d. ‘Journey to the Center of the Earth.’ Interactive. http://www.bbc.com/future/bespoke/story/20150306-journey-to-the-centre-of-earth/


http://atomictimeline.net/

https://pubs.usgs.gov/circ/1966/0532/report.pdf

https://www.youtube.com/watch?v=drCg4ruJCfA

https://www.youtube.com/watch?v=tWQwYQqd36A

https://www.youtube.com/watch?v=xUX-nmPL9SE

http://www.bbc.com/future/bespoke/story/20150306-journey-to-the-centre-of-earth/

A. Match the given description in column A with the term it is referring to

column B. Column A Column B

1. the outermost layer of Earth a. ocean ridges 2. major sections on the crust that are in b. deep ocean basins

constant motion relative to the other. c. crust 3. boundary between the crust and mantle d. Mohorovičić 4. most abundant element in Earth’s crust discontinuity 5. crust that is composed mostly of dark e. tectonic plates

colored mafic rocks f. oxygen 6. crust that has an average composition of g. iron

Granodiorite h. oceanic crust 7. a feature of the continental crust that are i. continental crust

elevated j. mountain belts 8. areas that are found between continental k. cratons

margins and ocean ridges 9. composed of newly formed oceanic crust

B. Correctly label the given figure by identifying the continental shelf,

continental slope, abyssal plain, continental crust, and the oceanic crust.


Answer the following questions.

1. Why is the crust the thinnest layer? 2. What makes Earth’s crust conducive for living organisms to survive? 3. Do you think it is possible for the Luzon island to move closer to the

Mindanao island? Why? 4. How is Earth’s crust formed? 5. Do you agree that the formation of the other planets’ crust is the same to

Earth’s crust? Explain.


Just like a hard-boiled egg with an outer shell and a fleshy egg white, Earth also has a layer that is inner to the crust that is referred to as the mantle. Having the largest volume, this layer is subdivided into simpler layers depending on its function. What are the layers of the mantle?

Egg-ARTH 2

Materials: ● hard-boiled chicken egg● metal knife● newspaper

Procedure: 1. Obtain the halved hard-boiled chicken egg.2. Examine the texture of the egg white of a hard-boiled chicken egg.3. Examine the thickness of the egg white relative to the thickness of the egg

shell and egg yolk.4. Carefully remove the egg yolk. Examine the hardness or elasticity of the egg

white.5. Set aside the halved egg on a newspaper.

Copyright © 2018 Quipper Limited15

Guide Questions: 1. What are the characteristics of the egg white? Use the table as a guide. Fill-in

the unshaded cells only.

Table 3. Observation of characteristics chicken egg layers


Texture

Thickness

Hardness

Elasticity



2. In terms of texture, is the egg white smooth or rough? 3. In terms of hardness, is the egg white rigid or elastic? 4. What can you say about the thickness of the egg white compared to the

other parts of the egg? 5. Do you think that the eggshell is an acceptable model for Earth’s mantle?

Why or why not? 6. What are the similarities between Earth’s mantle and an egg white that you

can think off?


Composition of Earth’s Mantle The mantle is by far the largest layer which accounts for about 83% of Earth’s volume. It is located between the thin crust and the core which extends to depths of 2 900 km. This layer is rich in magnesium oxide that distinguishes it from the crust. Magnesium oxide is resistant to changes when exposed to intense pressure and temperature. At a certain point when melting, this compound transcends from being an electrical insulator to a conductor. The bulk composition of the upper mantle is believed to be peridotites, dark-colored ultramafic igneous rocks. Peridotites are believed to be economically significant rocks which has ores of chromium from the chromite it contain. They can also be a source of diamonds. Most importantly, these rocks show potentials in sequestering carbon dioxide which humans can intentionally do to solve the drastically occurring climate change. The lower mantle is dominated by the mineral, bridgmanite, a type of perovskite. This mineral can only exist under high temperature conditions of at least 2 100 degrees Celsius, and high pressures of 240 metric tons per square centimeters, which is about 240 000 times the atmospheric pressure at sea level. It is in fluid state and moves slowly in the mantle.

Layers of the Mantle When Earth experiences ground movements and shaking during earthquakes, body waves are produced. These waves can be classified as p-waves, which can travel in liquids and solids or s-waves, which travel through solids only. Scientists who study the behavior of these waves have found out that there is a decrease in the velocity


of the waves in the upper mantle and increases as the waves reach the lower mantle. This findings suggest that the mantle may be divided into layers. Seismic studies have revealed that the mantle consists of layers including the lithosphere, asthenosphere, and mesosphere. The lithosphere is comprised of the crust and the uppermost part of the mantle. This layer is rigid (breaks under stress) and extends to depths of up to 150 km and has an average thickness of 100 km. The asthenosphere lies below the lithosphere. Here, rocks have plasticity and have the ability to flow. This allows the plates above this layer to move. The mesosphere is also called the lower mantle. This layer lies beneath the asthenosphere. This layer is composed of semi-solid ultrahigh-pressure silicates.

Mantle Convection Mantle convection refers to the transfer of heat from the mantle to the crust through the movement of mantle materials. The upward and downward motions of materials due to temperature differences allows the formation of convection currents.

Fig. 6. Mantle convection and the movement of mantle materials.


The temperature from the crust to the lower part of the mantle is generally increasing. This rate of increase in temperature with respect to depth is called the geothermal gradient. The geothermal gradient is around 15-30℃/km but actually varies per region. This temperature gradient increases slowly through the mantle and dramatically increases at its base, the core-mantle boundary known as Gutenberg discontinuity. Fig. 7 shows the relationship of depth and temperature of Earth which is also termed as the geothermal gradient.

● The mantle is the largest layer of Earth, and is subdivided into three layers: lithosphere, asthenosphere and mesosphere.

○ The lithosphere is comprised of the crust and the uppermost part of the mantle. This layer is rigid (breaks under stress) and extends to depths of up to 150 km and has an average thickness of 100 km.


○ The asthenosphere lies below the lithosphere. Here, rocks have plasticity and have the ability to flow. This allows the plates above this layer to move.

○ The mesosphere is also called the lower mantle. This layer is composed of semi-solid ultrahigh-pressure silicates.

● Mantle convection is the transfer of heat from the mantle to the crust. ● Temperature increases rapidly the nearer it gets to the core. ● The core-mantle boundary is known as Gutenberg discontinuity.

For further information, you can check the following web links:


● A video on drilling to Earth’s mantle and understanding the mantle User: Seeker. 2016. ‘What Can We Learn By Drilling Into The Earth's Mantle?’ Video. https://www.youtube.com/watch?v=QaYOGayEmFU






https://www.youtube.com/watch?v=QaYOGayEmFU



Fill in the blanks by providing appropriate terms from the word box.

Earth’s Mantle

The (1) ___________ is the middle layer of Earth. (2) ___________, a rich compound in this layer, is what distinguishes it from the outermost layer. (3) ___________ are produced when the ground experiences movements and earthquakes. This can be classified into (4) ___________, when it encompasses both liquids and solids, and (5) ___________, when it can only travel through solids. (6) ___________ is the boundary between this layer and the innermost layer of Earth. This layer is further subdivided into three layers. The (7) ___________ comprised of the outermost layer and the uppermost part of this layer. The (8) ___________ have fluccid rocks, thus have the ability to (9) ___________. The (10) ___________ is the innermost sublayer which has semi-solid ultrahigh-pressure (11) ___________. (12) ___________ refers to the transfer of (13) ___________ from the mantle to the (14) ___________ through the movement of mantle materials. Motions of materials due to temperature differences allows the formation of (15) ___________. The rate of increase in temperature with respect to depth is called the (16) ___________.

crust mantle flow heat

mantle convection lithosphere mesosphere asthenosphere

geothermal gradient

magnesium oxide body waves p-waves

s-waves silicates convection currents

Gutenberg discontinuity



1. How does temperature change as one goes from the surface to the center of Earth?

2. What is the difference between the lithosphere and the asthenosphere? 3. What prevents scientist and geologist to study the deeper layers of Earth? 4. What evidence does geologist use to study the internal structure of Earth? 5. Does Earth’s magnetic property due to the characteristics of the mantle?

Explain your answer.


Comparable to a hard-boiled egg, Earth has an innermost layer called the core. Surprisingly, this layer can be further divided into two layers, namely: the outer and inner core. What are the differences between these two layers of Earth’s core?

Egg-ARTH 3 Materials:

● hard-boiled chicken egg ● metal knife ● newspaper

Procedure:

1. Obtain the halved hard-boiled chicken egg. 2. Examine the texture of the egg yolk of a hard-boiled chicken egg. 3. Examine the thickness of the egg yolk relative to the thickness of the egg

shell and egg white. 4. Examine the hardness or elasticity of the egg yolk. 5. Set aside the halved egg on a newspaper.


Guide Questions: 1. Complete the table below. Fill-in the unshaded cells only.

Table 4. Observation of characteristics of chicken egg layers


Texture

Thickness

Hardness

Elasticity



2. In terms of texture, is the egg yolk smooth or rough? 3. In terms of hardness, is the egg yolk rigid or elastic? 4. What can you say about the thickness of the egg yolk compared to the other

parts of the egg? 5. Do you think that the egg yolk is an acceptable model for Earth’s core? Why

or why not? 6. What are the similarities between Earth’s core and an egg yolk that you can

think off?

The core is the innermost layer of Earth. It is 3480 km thick and its depth starts from 2900 to 6380 km. The boundary between the inner and outer core is called the Lehmann discontinuity. Abundant Elements in Earth’s Core In the early years of Earth’s formation, the dense materials such as iron and nickel sank to the center forming the core. In general, the core is composed mainly of iron


which is about 85%. Nickel is also present at 5% alongside other lighter elements which are 10% of the layer. These lighter elements include sulfur, oxygen, carbon and hydrogen. These lighter elements play and important part in the convection of of the outer core which is fluid, hence, was able to generate Earth’s magnetic field.

Fig. 8. The core.

Layers of the Core The core can be divided into two parts: outer and inner core. Seismic studies are also responsible for discovering these two layers of the core. The outer core is a liquid layer, 2260 km thick. The temperature in this region is very high allowing the melting of materials. Temperature in the outer core ranges from 4500 °C to 6000 °C. Turbulent flow of iron in the outer core is believed to be responsible for the generation of Earth’s magnetic field.


Fig. 9. Earth’s magnetic field.

The inner core is the innermost layer of Earth. It is also composed of iron and nickel and light elements. Unlike outer core, this layer is in solid phase. This was also discovered through seismic studies. Temperature in this region ranges from 6000°C and higher, but the pressure is high enough for the materials to stay solid. The inner core is about 70% of the size of the Moon. The temperature in the inner core is the same as the temperature at the surface of the sun.

Formation of the Core Researchers believed that the core was already formed when the Solar System was very young. Data showed that the core was formed around 1 to 1.5 billion years ago when the solid inner core was just beginning to solidify. This accounts for the increasing magnetic field strength of Earth compared to the beginning fluid core. Studie also explained that compared to the earlier years of Earth when the core was in in a rapid change of state form liquid to solid, the cooling in the inner core was slower today. This solidifying process of the inner core strengthens Earth’s magnetic field.


● The core is the innermost layer of Earth. It is 3480 km thick and its depth starts from 2900 to 6380 km.

● The boundary between the inner and outer core is called the Lehmann discontinuity.

● The core is divided into two parts: the outer and inner core. ○ The outer core is in liquid phase, whereas the inner core is in solid

phase. ● The core is composed mainly of iron which is about 85%. Nickel is also

present at 5% alongside other lighter elements which are 10% of the layer.

For further information, you can check the following web links:


● A video of Earth’s core and its discovery User: Seeker. 2016. ‘The Core of the Earth | 100 Greatest Discoveries.’ Video. https://www.youtube.com/watch?v=WCeSP8bqY1w






https://www.youtube.com/watch?v=WCeSP8bqY1w



Write true if the given statement is correct otherwise, put the word false.

1. Earth’s inner core consists of molten metal. 2. The outer core is solid. 3. The mantle is the innermost layer of Earth. 4. Dense materials such as iron and nickel are found in Earth’s core. 5. The boundary between the inner and outer core is called Lehmann

discontinuity. 6. The turbulent flow in the inner core is responsible for the generation of

Earth’s magnetic field. 7. The inner core has higher pressure compared to the outer core. 8. The iron and nickel of Earth’s inner core are in solid phase. 9. The iron composition of the core is roughly about 85%.

10. Lehmann discontinuity is the boundary between the inner mantle and the outer core.

11. The core is the thinnest layer of Earth. 12. The inner and outer core are solid layers. 13. The core is the largest layer of Earth. 14. There is a turbulent flow of materials found at the inner core. 15. The outer core is the same as the temperature at the surface of the sun.


1. Is it possible for scientists to physically journey to the center of Earth? Why or why not?

2. If Earth has a hole passing through the center to the other side of Earth, what will happen to a person who will jump through it? Explain.

3. Why does the outer and inner core have different states? 4. How does Earth form its magnetic property? 5. Does Mars have a similar core to that of Earth? State evidence.


Earth can be compared to a hard-boiled egg with the crust as its shell, mantle as its egg white, and the core as its egg yolk. With Earth being a terrestrial planet makes it comparable with the other terrestrial planets in our solar system. Does Earth have similar layers with the other terrestrial planets?

The Terrestrial Planets Materials:

● 1 piece medium-sized mango ● 1 piece medium-sized avocado ● 1 piece grape ● 1 piece lychee ● knife

Procedure:

1. Slice each fruit in half. 2. Observe the internal structure of each fruit in terms of texture, thickness and

hardness. Guide Questions:

1. Identify which model fruit represents Mercury, Venus, Earth, and Mars? Why? 2. Using the fruit models of the planet, what similarities have you observed

among the terrestrial planets? Describe each similarity through the fruit models.


3. Using the fruit models, what are the differences among the terrestrial planets? Describe each difference through the models.

4. Do all other terrestrial planets have similar layers to that of Earth? What are these layers?

Earth has three distinguished layers: the crust, the mantle, and the core. It shares similar characteristics to other planets especially the inner or terrestrial planets. This makes Mercury, Venus, and Mars to have similar layers with Earth.

Fig.10. The layers of Earth and their boundaries.

Mercury Mercury is the smallest terrestrial planet. Although small, it is one of the densest planets second to Earth. The planet is believed to be composed of a core, mantle, and crust. The planet’s core makes up around 85% of the planet’s radius. The radius of this core is about 1 800 to 1 900 km. The core has more iron than any other planet in the solar system. Radar images from Earth reveal that the core of Mercury is liquid. Only a thin layer covers the core.


Scientists have formulated two hypotheses explaining the existence of the large core of the planet. One possible explanation is the planet’s fast formation. Mercury may have formed quickly and the increasing temperature of the cooling sun vaporized much of the surface leaving only a thin shell. Another explanation is attributed to the impacts in the planet during its early formation. The impacts may have stripped away the outer shell of the planet leaving a big core. The core generates a magnetic field about one percent as strong as that of Earth’s.

Venus Venus is the second planet from the Sun. It is believed to have compositions similar to Earth. Scientists speculate that the planet also has crust, mantle, and core. The crust of Venus is believed to be significantly older than Earth’s. This is due to Earth’s constantly changing surface. The crust is believed to extend from 10 to 30 km from the surface. The planet’s mantle is believed to be rocky. It extends to depths of 3 000 km. Venus’ core is believed to be composed of iron-nickel alloy. The core is believed to be in liquid


state. The slow spin of Venus compared to Earth makes scientists speculate that the planet has a weak magnetic field.

Mars Mars, popularly known as the red planet, is also composed of outer crust, mantle, and core. The crust of Mars is composed mostly of dust on the surface and basaltic rocks underneath. It is believed to extend to up to 50 km. The crust is believed to be ‘one piece,’ meaning, it has no mobile tectonic plates, unlike Earth. Eruptions take place at the same point for a long time building up huge volcanoes in the surface such as Olympus Mons, the Solar System’s largest mountain. The planet’s mantle is made up of silicon, oxygen, iron, and magnesium. It is believed to have a consistency similar to a rocky paste. The mantle is believed to be 5 400 to 7 200 km thick. The core of Mars is believed to be solid. It is composed of iron, nickel, and sulfur. It is 3 000 to 4 000 km in diameter. Because the core is solid and does not move, Mars has no magnetic field. The absence of magnetic field allows the bombardment of radiation making the planet not suitable for liquid water and life.


Table 2. Characteristics of the internal structures of the terrestrial planets.

Layers

Prominent Features in Terrestrial Planets

Mercury Venus Earth Mars

crust has prominent crust

has older crust than Earth

thin rocky crust dusted surface with basaltic rocks underneath

mantle has a thin mantle

rocky mantle large volume is mostly from mantle

composed of silicon, oxygen, iron and magnesium

core makes up 85% of the planet’s radius

composed of liquid iron-nickel alloy

core is in liquid and solid state (layers)

solid core

prominent features

small and dense planet

has weak magnetic field

has many volcanoes, moving crust

one piece crust, has Olympus Mons

● Mercury, Venus, Mars, and Earth are terrestrial planets or inner planets. ● All terrestrial planets have similar layers: a crust, a mantle, and a core.

○ Mercury is a small and dense planet that has prominent crust, and a thin mantle. The core makes up 85% of the planet’s radius.

○ Venus has weak magnetic field. It also has older crust than Earth and rocky mantle. The core is composed of liquid iron-nickel alloy.

○ Mars has a crust with dusted surface with basaltic rocks underneath. The mantle is composed of silicon, oxygen, iron and magnesium. Mar’s core is a solid core


For further readings, you can check the following web links:

● Read and watch a video about Mercury Cosmos4kids.com. n.d. ‘Mercury - The Hot Planet.’ http://www.cosmos4kids.com/files/solsyst_mercury.htm

● Read and watch a video about Venus Cosmos4kids.com. n.d. ‘Venus In The Number Two Position’ http://www.cosmos4kids.com/files/solsyst_venus.html

● Read and watch a video about Mars Cosmos4kids.com. n.d. ‘Mars In The Fourth Position’ http://www.cosmos4kids.com/files/solsyst_mars.html

A. Complete the following table by providing the needed information for each cell .

Characteristics of the internal structures of the terrestrial planets.

Layers and prominent

features

Mercury Venus Earth Mars

crust has prominent crust

(1) thin rocky crust

(2)

mantle has a thin mantle

(3) (4) composed of silicon, oxygen, iron and



http://www.cosmos4kids.com/files/solsyst_mercury.html


http://www.cosmos4kids.com/files/solsyst_venus.html


http://www.cosmos4kids.com/files/solsyst_mars.html

magnesium

core (5) composed of liquid iron-nickel alloy

(6) (7)

prominent features

(8) (9) has many volcanoes, moving crust

(10)

B. Complete the following term analogy.

1. Earth: Mount Apo : : Mars: _______ 2. Earth: strong magnetic field : : Venus: _______ 3. Earth: _______ : : Mercury: mostly core 4. Venus: liquid core : : Mars: _______ 5. Venus’ core: _______ : : Earth’s core: iron and nickel


1. Between the two hypotheses of the existence of the large core of Mercury, which do you favor more? Why?

2. What could be the reason why Venus have a slow spin and a weak magnetic field? Explain.

3. Does Mars spin like the other terrestrial planet? Why? 4. Among the three terrestrial planets, which is the most similar to Earth‘s

internal structure? Why? 5. What makes Earth’s crust different from the crust of the other terrestrial

planets? Cite evidence.


Activity 3.1

A Model of Earth’s Crust, Mantle, and Core

Objectives At the end of this laboratory activity, the students should be able to:

● compare the temperature of the layers of Earth model; ● justify the cause of the temperature difference; ● explain how the crust is formed; and ● describe the characteristics of Earth’s crust, mantle, and core.

Materials and Equipment

● timer ● gelatin mix ● crushed graham ● hot water ● 3 thermometers ● 2 pots or pans (one pot/pan must be wider than the other) ● spoon or spatula

Procedure

1. Prepare the gelatin mix according to package instruction. Set aside. 2. In a smaller pot, placed the crushed graham. Press and distribute properly

over the bottom of the pan. 3. Place the small pot inside a larger pot with hot water (at the same

approximate level of the crushed graham). Make sure that this water maintains a temperature of 80 to 85 ℃.

4. Carefully pour the prepared liquid gelatin over the crushed graham. 5. Place one thermometer in the crushed graham layer, one thermometer in

the liquid gelatin layer and one thermometer on the surface of the gelatin layer.

6. Record the final temperature of the three thermometers on Table 4. 7. Observe what happens to the gelatin on the surface, and on top of the

graham after 15 minutes. 8. Record the final temperature of the three thermometers on Table 4.


Data and Results

Table 1. Temperature of the layers of Earth model.

Layer

Initial Temperature,

℃

Final Temperature,

℃

Crushed graham

Gelatin layer (above the graham)

Surface of the gelatin

Guide Questions

1. What happens to the temperature of the layers of Earth model as you go deeper in the pan? What causes this temperature differences?

2. Which layer has the lowest temperature? Why? 3. Which layer has the highest temperature? Why? 4. Does the final temperature of the surface of the gelatin change? Does it

increase of decrease? Why? 5. What happens to the surface of the gelatin? What causes this change? 6. Relatively to Earth’s internal structure, which is the core in the model? The

mantle? The crust? Why? 7. Using the observed change in the model, how does Earth formed it’s crust? 8. What is the texture and consistency or plasticity of the middle layer? In what

way(s) does this layer relate to the mantle? 9. What is the texture and consistency or plasticity of the crushed graham? In

what way(s) does this layer relate to the core?


A Journey to the Center of Earth Goal

● Your group’s goal is to inform your TV viewers of the facts concerning the internal structure of Earth.

Role

● You are a group of young scientists and geologist who want to inform your viewers

on the interesting facts about the internal structure of Earth. Audience

● Your audience is your TV viewers on your weekly morning show in a TV channel.

Situation

● The challenge is to inform your viewers on the amazing facts about Earth’s internal structure, and to fascinate them on how deep the center is using visual effects.

Product, Performance, and Purpose You will create a video of your group presenting your researched facts. Standards and Criteria for Success

Criteria Below

Expectations, 0% to 49%

Needs Improvement

50% to 74%

Successful Performance 75% to 99%

Exemplary Performance

100%

Content. Detailed facts are presented well. Content related to the task.

Details not presented. Content is not related to the task.

Details are presented but not organized. There are some content that are not related to task.

Details are presented in an organized manner.Content are related to the task.

Details are presented in an organized matter that can be easily understood. Content are related to the task. Additional


supporting details are presented.

Communication Skills. Presentation was done in a clear and logical manner.

Presentation was not done.

Presentation was done but in a disorganized and illogical manner.

Presentation was done smoothly but the concepts are presented in such a way that should be rearranged for better understanding.

Presentation was done clearly. Concepts were presented in a logical manner and easily understandable by the audience.

Quality. Presentation was edited to enhance the concept.

There is no movie, or tape is totally unedited with no transition or audio support of any kind.

Movie is made but has very little if any editing. Many poor shots remain. Video is very fragmented and choppy with little to no audio reinforcement.

Movie is completed and contained all required items. Editing is not done as well as it should have been. Some poor shots remain. Movie is still somewhat choppy.

Movie is completed with all required elements. The video is well edited and moves smoothly from scene to scene with proper use of transitions. Audio and other enhancements are well used.

After studying this unit, can you now do the following?

Check I can…

describe Earth’s crust.

describe Earth’s mantle.

describe Earth’s core.

describe the layers of the other terrestrial planets.

compare Earth’s layers with the other terrestrial planet’s layers.


Asthenosphere It lies below the lithosphere. Here, rocks have plasticity and have the ability to flow.

Continental crust It is composed of many rock types, mostly of granodiorite, a light-colored igneous rock.

Continental margin It separates continental crust from oceanic crust.

Core It is the innermost layer and is subdivided into the outer and inner core.

Crust It is the outermost and thinnest layer of Earth.

Gutenberg discontinuity

It is the boundary between the mantle and the core.

Lithosphere It is comprised of the crust and the uppermost part of the mantle.

Mantle It is the largest layer of Earth and is subdivided into lithosphere, asthenosphere, and mesosphere.

Mantle convection It is the transfer of heat from mantle to the crust through the movement of mantle materials.

Mars It is also called the red planet.

Mercury It is the smallest terrestrial planet.

Mesosphere It is also called the lower mantle.

Mohorovičić discontinuity

It is the boundary between the crust and the mantle.

Mountain belts It is the elevated region composed of uplifted and deformed rocks.

Ocean ridges It is composed of newly formed oceanic crust which has been uplifted and faulted.

Oceanic crust It is composed mostly of dark colored mafic rocks.

Venus It is the second planet from the sun.


Layers of Earth and Comparison to other Terrestrial Planets

Baker, Don et al. 2017. “A metasomatic mechanism for the formation of Earth’s

earliest evoled crust.” Earth and Planetary Science Letters. Earle, Steven. Physical Geology. British Columbia Campus Open Textbook Project.

British Columbia. Gammon, Katharine. 2015. “Terrestrial Planets: Definition & Facts About the Inner

Planets.” Accessed May 9, 2017. http://www.space.com/17028-terrestrial-planets.html


Hefferan, Kevin and O’Brien, John. 2010. Earth Materials. John Wiley & Sons, Ltd.,

Publication. United Kingdom. King, H. M. (n.d.). Peridotite. Retrieved from Geology.com:

https://geology.com/rocks/peridotite.shtml Marshak, Stephen. 2009. Essentials of Geology 3rd Edition. New York: W.W. Norton

& Co. Inc. National Aeronautics and Space Administration. “Terrestrial Planet Interiors.”

Accessed May 9, 2017. https://solarsystem.nasa.gov/galleries/terrestrial-planet-interiors

National Geographic. “crust.” Accessed May 9, 2017.

https://www.nationalgeographic.org/ encyclopedia/crust/ Plait, P. (2014). Scientists Discover 38 Percent of the Earth. Retrieved from Slate:

http://www.slate.com/blogs/bad_astronomy/2014/12/18/bridgmanite_high_pressure_mineral_makes_up_most_of_earth.html

Redd, Nola Taylor. 2016. “What is Mercury Made of?” Space.com. Accessed May 9,

2017. http://www.space.com/18643-mercury-composition.html Redd, Nola Taylor. 2012. “What is Venus Made of?” Space.com. Accessed May 9,

2017. http:// www.space.com/18525-venus-composition.html Sawe, Benjamin Elisha. 2018. “The Most Abundant Elements In The Earth.” world

astlast.com. Accessed May 14, 2018. https://www.worldatlas.com/articles/the-most-abundant-elements-in-the-earth-s-crust.html

Science, C. I. (2012). Magnesium oxide: From Earth to super-Earth. Retrieved from

Phys.org: https://phys.org/news/2012-11-magnesium-oxide-earth-super-earth.html

ScienceDaily. (2015). Retrieved from Earth's inner core was formed 1-1.5 billion

years ago: https://www.sciencedaily.com/releases/2015/10/151007135656.htm


Sharp, Tim. 2012. “What is Mars Made of| Composition of Planet Mars?” Accessed

May 10, 2017. http://www.space.com/16895-what-is-mars-made-of.html Staff, L. S. (2011). Earth's Core Starved for Oxygen. Retrieved from Life Science:

https://www.livescience.com/17202-earths-core-oxygen-starved.html Tarbuck, Edward J. and Lutgens, Frederick K. 2015. Earth Science. 14th edition.

Pearson Education Inc. USA. Williams, Matt. 2015. “What are the Earth’s layers?” Universe Today Phys.org.

Accessed February 17, 2017. https://phys.org/news/2015-12-earth-layers.html


unit 3 earth’s internal structure

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