Structure of Earth and Composition – Crust Mantle Outer and Inner Core

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• Structure of Earth
• Crust
• Crust & Rocks
• Upper & Lower Mantle
• Outer & Inner Core
• Things to Remember

Recommended: Interesting Facts about Earth Planet

Structure of Earth

The waves that travel through Earth’s layers and are of result of earthquakes, volcanic eruption, large landslide or man-made explosion are called _________?

1. ultrasonic waves
2. seismic waves
3. sound waves
4. electromagnetic waves

Earth can be divided into crust, mantle, outer core and inner core on the basis of _________

1. chemical properties
2. retrospective properties
3. mechanical properties
4. electrical properties

The transition of rocks from one form to another is called _______?

1. hydrological cycle
2. rock cycle
3. transition zone
4. metamorphic cycle

When seismic waves change their speed and direction?

1. when they go beyond their assigned limits
2. when they hit troposphere
3. when they cross a boundary from one type of material to another
4. None of these

 Earth can be divided into lithosphere, asthenosphere, mesosphere, outer core and inner core on the basis of _______

1. chemical properties
2. electrical properties
3. retrospective properties
4. mechanical properties

Crust

What is the thickness of crust in ocean basins?

1. 1 – 10 km
2. 5 – 10 km
3. 9 – 21 km
4. 10 – 15 km

How many types of rocks can be found in crust?

1. 1
2. 3
3. 5
4. 7

The boundary between crust and mantle is called _______.

1. Toho
2. Moho
3. Oho
4. Kohkas

What are the two distinct types of Earth’s crust?

1. Oceanic, continental
2. plains, plateau
3. hills, mountains
4. magma, prairie

What is the density of crust at the bottom?

1. 1.9 g/cm³
2. 2.9 g/cm³
3. 3.9 g/cm³
4. 4.9 g/cm³

What we call that point where seismic waves change velocity?

1. continuity
2. seismic point
3. discontinuity
4. continuity & discontinuity

The outermost layer of earth is called ________.

1. core
2. transition zone
3. lower mantle
4. crust

What is the thickness of crust in continents?

1. 40 – 70 km
2. 60 – 100 km
3. 70 – 150 km
4. 80 – 200 km

The outermost layer of crust is mainly composed of _________.

1. nickel – iron alloy
2. alumino – silicates
3. magnesium – silicates
4. stainless steel

What is the density of crust at the top?

1. 5.2 g/cm³
2. 4.2 g/cm³
3. 3.2 g/cm³
4. 2.2 g/cm³

Three – quarter of earth’s crust is covered with ______ .

1. plains
2. prairie
3. plateau
4. water

What is Mohorovicic discontinuity?

1. boundary between crust and mantle
2. boundary between inner core & crust
3. boundary between inner core and upper mantle
4. None of these

Crust and Rocks

The rocks that are formed from the sediments that get buried, compacted and cemented together into a single rock are called ___________.

1. metamorphic rocks
2. intrusive
3. extrusive
4. sedimentary rocks

Rocks which are form from the cooling and hardening of magma or lave?

1. Sedimentary
2. metamorphic
3. chemical sediments
4. igneous

Igneous rocks are classified into ____________ types of igneous rocks.

1. 3
2. 2
3. 5
4. 4

Molten rock inside the earth is ________.

1. lava
2. organic waste
3. biological waste
4. magma

Any coherent, naturally occurring solid material consisting of one or more minerals is called _________?

1. rock
2. latitude
3. longitude
4. core

The broken pieces of rocks by the process of weathering is called _________.

1. sediments
2. igneous
3. transitional rocks
4. extrusive

Molten rock flowing across earth’s surface.

1. lava
2. biological sediments
3. organic waste
4. magma

What is the literal meaning of “Meta”?

1. change
2. retardation
3. cycle
4. pre-heated

Sedimentary rocks are classified into clastic, chemical and _____________ sedimentary rocks.

1. giant
2. metamorphic
3. igneous
4. biological or organic

Foliated and non-foliated are the types of ___________.

1. crust
2. metamorphic
3. sedimentary
4. intrusive

Conglome rate, Breccia, Sandstone, Siltstone, Mudsonte and Shale all are an example of _______.

1. limestone
2. dolomite
3. clastic rocks
4. organic rocks

The formation of rocks due to accumulation of dead animals and plants are called _______.

1. extrusive igneous rocks
2. metamorphic
3. clastic rocks
4. organic rocks

The word “Meta” is came from the following language.

1. Latin
2. Greek
3. Turkish
4. Portuguese

The rocks which are formed when magma solidifies below the earth crust are called ______.

1. extrusive
2. intrusive
3. prairie
4. explosive

What we call that rocks that are formed due to mechanical weathering of rock forms.

1. clastic
2. chemical
3. organic
4. biological

Limestone, Dolostone & Evaporites all are an example of _________ sedimentary rocks.

1. biologic
2. non-foliated
3. foliated
4. chemical

What is the literal meaning of “Morphs”?

1. cycle
2. rock
3. acceleration
4. form

Basalt, Andesite, Dacite and Rhyolite are examples of ________.

1. sedimentary
2. foliated
3. intrusive
4. extrusive

The rocks that came into being when any rock is exposed to extreme heat & pressure are called _________.

1. igneous
2. metamorphic
3. sedimentary
4. extrusive

Rocks that have layered or banded appearance for example gneiss, slate and schist are called ________.

1. foliated metamorphic rocks
2. non-foliated metamorphic rocks
3. intrusive igneous rocks
4. biological sedimentary rocks

Rocks that have not layered or branded appearance and produced by the exposure to heat and directed pressure such as marble, quartzite are called ______.

1. clastic sedimentary rocks
2. non-foliated metamorphic rocks
3. chemical sedimentary rocks
4. foliated metamorphic rocks

Gabbro, Diorite, Granodiorite, Granodiorite Granite are examples of _________.

1. asthenosphere
2. core
3. extrusive
4. intrusive

Coal and Chert are example of _______ sedimentary rocks.

1. extrusive
2. biologic
3. dolomite
4. quartzite

What we call the rocks that are formed due to chemical reactions of minerals present in rocks forms settles down as precipitate and converts to rock forms over a period of time.

1. Chemical sedimentary rocks
2. igneous rocks
3. intrusive igneous rocks
4. organic sedimentary rocks

The rocks which are formed when magma comes out in lava form and cools down are called __________.

1. intrusive
2. explosive
3. extrusive
4. prairie

Mantle – Upper and Lower Mantle

Starting from Moho, what is the maximum depth of upper mantle?

1. 100 km
2. 200 km
3. 300 km
4. 400 km

What is the density of the lower mantle at the top?

1. 32.4 g/cm³
2. 16.4 g/cm³
3. 8.4 g/cm³
4. 4.4 g/cm³

The upper mantle contains a zone, which is a zone of weakness, what it’s name?

1. lithosphere
2. asthenosphere
3. mesosphere
4. hydrosphere

What is the density of the upper mantle at the top?

1. 1.4 g/cm³
2. 3.4 g/cm³
3. 5.4 g/cm³
4. 7.4 g/cm³

What is the maximum depth of mantle?

1. 1900 km
2. 2900 km
3. 3900 km
4. 4900 km

What is the main component of mantle?

1. oxygen and oxides of nitrogen
2. iron- nickel alloy
3. ferro – magnesium silicates
4. None of these

What is the density of the upper mantle at the bottom?

1. 10.4 g/cm³
2. 8.4 g/cm³
3. 6.4 g/cm³
4. 4.4 g/cm³

The scientists who study earthquakes and planetary activities as well as their effects such as tsunami are called _________?

1. physicist
2. chemist
3. seismologist
4. technician

What is the composition of upper mantle?

1. iron & magnesium silicates
2. hydrogen and carbon dioxide
3. nitrogenous oxide
4. iron alloy

What is the temperature at the core – mantle boundary?

1. 4,000^oC
2. 6,000^oC
3. 8,000^oC
4. 10,000^oC

What is the name of zone where minerals undergo a process, in which they change in structure and forms other atomic arrangements?

1. asthenosphere
2. troposphere
3. exosphere
4. transition zone

What is the density of the lower mantle at the bottom?

1. 5.6 g/cm³
2. 7.6 g/cm³
3. 9.6 g/cm³
4. 11.6 g/cm³

Outer and Inner Core

What is the thickness of outer core?

1. 2,300 km
2. 2,500 km
3. 27,00 km
4. 2,900 km

What element is fairly available in inner core?

1. oxygen
2. nitrogen
3. silicon
4. iron

What is the density of the inner core at the top?

1. 18.8 g/cm³
2. 16.8 g/cm³
3. 14.8 g/cm³
4. 12.8 g/cm³

Which of the following is associated with the earth’s magnetic field?

1. inner core
2. outer core
3. upper mantle
4. lower mantle

What is the density of the outer core at the top?

1. 5.9 g/cm³
2. 7.9 g/cm³
3. 9.9 g/cm³
4. 11.9 g/cm³

What is core?

1. first layer
2. last layer
3. second last
4. middle layer

What is the state of inner core?

1. liquid
2. plasma
3. solid
4. liquid & solid

What is the state of outer core?

1. solid
2. transitional
3. plasma
4. liquid

What is the density of the inner core at the bottom?

1. 11.1 g/cm³
2. 13.1 g/cm³
3. 15.1 g/cm³
4. 17.1 g/cm³

What is the thickness of inner core?

1. 1,600 km
2. 1,400 km
3. 1,200 km
4. 1,000 km

Following is the composition of the outer core?

1. ferro – magnesium silicates
2. nickel – iron alloy
3. oxygen oxides
4. phenyl and benzene

What is the density of the outer core at the bottom?

1. 12.2 g/cm³
2. 14.2 g/cm³
3. 16.2 g/cm³
4. 18.2 g/cm³

Structure of Earth – Things to Remember

Seismic Waves

Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.

Seismologist

Seismologists are scientists who study earthquakes and planetary activities as well as their effects, such as tsunamis. They use instruments to gather data and monitor the Earth’s crust. The top most layer is the Lithosphere, which comprised the crust and solid portion of the upper mantle. Seismologists usually work in offices or laboratories, but may travel to sites of seismic activity.

Structure of Earth – Crust, Mantle and Core

• By chemical properties, Earth can be divided into crust, mantle, outer core, inner core and by mechanical properties, it can be divided into lithosphere, asthenosphere, mesospheric mantle, outer core and inner core. Each division has specific characteristics i.e. density, temperature, composition etc. etc.

• The top most layer is called crust which has variable thickness, being 5 – 10 km in ocean basins and 40 – 70 km thick in continent as it comprises continents and ocean basins. The temperature within the deepest part goes up to 800^oC. It is composed of alumino – silicates. It has 2.2 g/cm³ at the top and 2.9 g/cm³ at the bottom.

• Three types of rocks can be found in the crust i.e. igneous, sedimentary and metamorphic rocks. Igneous rocks form from the cooling and hardening of magma or lava. If magma cools down below the Earth’s crust, it is called intrusive igneous rocks and if it comes outside in lava form, it is called extrusive igneous rocks.

• Broken pieces of rocks are called sediments. Weathering is a process through which rocky materials break down. The rocks that are formed from sediments that get buried, compacted and cemented together in to a single rock are called sedimentary rocks. These rocks are classified into organic, clastic and chemical sedimentary rocks.

• Chemical sedimentary rock is formed when minerals, dissolved in water, begin to precipitate out of solution and deposit at the base of the water body.

• Clastic sedimentary rocks are formed when rock layers are formed due to mechanical weathering of rock forms.

• The biologic or organic sedimentary rocks form mainly comprise of coal and limestone which are formed due to deposition and accumulation of dead plants and animals in rock layers.

• Metamorphic is derived from Greek word “Meta” means change and “Morphs” means form. These types of rocks are formed when rocks are exposed to extremely heat and pressure. The rocks which have layered or branded appearance are called foliated and others haven’t any such appearance are called non-foliated i.e. marble and quartzite.

• Moho is a boundary between crust and upper mantle. So next layer is mantle which goes about 2,900 km deep. It is subdivided into upper and lower mantle. The upper mantle is 400 km deep and possesses density ranging from 3.4 g/cm³ to 4.4 g/cm³. Within upper mantle is a zone called the asthenosphere (zone of weakness). It is mainly composed of iron, magnesium silicates.

• Between the lower and upper mantle, there is a zone (400km to 670 km deep) where minerals undergo a process called phase transition, in which they change in structure and form other atomic arrangements. This zone is called transition zone.

• The mantle below 670 km is called lower mantle where density further increased 4.4 g/cm³ to 5.6 g/cm³ due to the increase in pressure. It is believed that lower mantle is denser than upper mantle.

• Core is the last layer which is categorized into outer and inner core. The strange thing about core is that the state of outer core is liquid and it is believed that Earth’s magnetic field is due to the this liquid outer core which is composed of nickel – iron alloy & inner core is solid which is almost entirely composed of iron. The outer core has density 9.9 g/cm³ to 12.2 g/cm³ at the top and bottom and inner core has 12.8 g/cm³ to 13.1 g/cm³ at the top and bottom respectively. The outer core is 2,300 km and inner core is 1,200 km thick.

Rock Cycle

Igneous rocks can be change into sedimentary rocks, sedimentary rocks can be change into metamorphic rocks and metamorphic rocks can be changed into igneous rocks or sedimentary rocks. It is a group of changes which is called Rock Cycle. It is driven by two forces.

• The internal heat of earth which moves material around in the core and the mantle and leads to slow but significant changes within the crust.

• Hydrological cycle, which is the movement of water, ice and air at the surface and is powered by the sun.