1st PUC Geography Question Bank Chapter 3 Interior of the Earth

Students can Download 1st PUC Geography Chapter 3 Interior of the Earth Questions and Answers, Notes Pdf, 1st PUC Geography Question Bank with Answers helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.

Karnataka 1st PUC Geography Question Bank Chapter 3 Interior of the Earth

1st PUC Geography Interior of the Earth Text Book Questions and Answers

I. Answer the following in a word or a sentence each.

Question 1.
What is Continental Crust?
Answer:
The continental crust is the upper most layer of the earth and around 30km thick and contains silica and aluminium (sial)

Question 2.
Name the discontinuity found between Mantle and Core.
Answer:
Gutenberg/oldham discontinuity.

Question 3.
Why is the inner core called ‘Solid Core’?
Answer:
Beeause most of the materials are in solid form.

Question 4.
Name the instrument used to record seismic waves.
Answer:
Seismograph.

Question 5.
Which is the most destructive earthquake wave?
Answer:
Surface waves.

Question 6.
Define Tsunami.
Answer:
A large sea wave occasionally experienced along the sea coast caused by an underwater or sub-marine earth-quake is called ‘Tsunami”.

Question 7.
What is Homo-Seismal line?
Answer:
Homo-Seismal lines are the lines drawn on the map to show the places recording the same time of occurrence of earthquake.

Question 8.
Mention the region which record more seismic activities in the world.
Answer:

1. The circum-pacific belt
2. The mid- Atlantic belt
3. The mid-continental belt
4. Siwalik belt

Question 9.
What is Volcano?
Answer:
Volcano is a vent or opening, through which heated materials consisting of gases, hot water, lava and fragments of rocks are ejected from the interior of the Earth.

Question 10.
Name any one volcano of India.
Answer:
Barren island of Andaman and Nicobar islands in India.

Question 11.
Which is a famous active Volcano in USA?
Answer:
St. Helens of USA

Question 12.
What is‘Ring of Fire?
Answer:
The circum-pacific belt is called the pacific ‘ring of fire’

Question 13.
Define petrology.
Answer:
The scientific study of rocks is called petrology.

Question 14.
Give an example for plutonic rock.
Answer:
Granite

Question 15.
Why are secondary rocks called Aqueous rocks?
Answer:
Because they are formed by water.

Question 16.
How is Carbonaceous rock formed?
Answer:
Carbonaceous rocks are formed by the decay and decomposition of plants, trees and vegetation and are rich in carbon. Eg-coal.

Question 17.
What is Metamorphism?
Answer:
Metamophism means change of form either physical or chemical, due to the influence of temperature and pressure.

Question 18.
What is a Mineral?
Answer:
Mineral is a natural inorganic substance which has certain chemical and physical properties.

Question 19.
Which mineral covers largest area of the Earth’s crust?.
Answer:
Feldspar which is rich in silica and oxygen is found in more than half of the Earth’s crust.

Question 20.
Give an example for non-ferrous mineral.
Answer:
Bauxite.

II. Answer the following in two or three sentences each.

Question 1.
Mention any two features of Oceanic Crust.
Answer:
Oceanic Crust:

1. It is around 5km thick.
2. It is rich in silica and magnesium (sima).

Question 2.
Why is Mantle very important in the Earth’s interior?
Answer:
The Mantle is composed of dense and rigid rocks which have minerals like Magnesium and Iron (olivine). Dusing Earthquakes, which originate due the disorders in the upper mantle, these minerals are deposited on the crust of the earth from where the minerals can be mined and used for commercial and domestic purpose.

Question 3.
Satae the Difference between Focus and Epicentre.
Answer:
The place of origin of an Earthquake in the Earth’s crust is called ‘Focus’. The point on the Earth’s surface which is perpendicular to the focus, receining seismic waves is called ‘Epicentre’ ofthe Earthquake.

Question 4.
Name any two causes for earthquakes.
Answer:

• Tectonic Earthquakes
• Volcanic Earthquakes.

Question 5.
Distinguish between Iso-seismal and Co-seismal lines.
Answer:

1. Iso-seismal: Lines drawn on the map to show the places experiencing the same intensity of Earthquake.
2. Co-seismal: Lines drawn on the map to show the places experiencing same intensity and same time of occurence of earthquke.

Question 6.
Which scales are used to measure the intensity of an earthquake?
Answer:

1. Richter Scale: used to Measure Magnitude of an earthquake
2. Mercalli-Scale: used to measure the Intensity of an earthquake

Question 7.
Mention any two causes of a Volcano.
Answer:

1. Movement and breaking of major and minor plates of the Earth.
2. Ascent of magma forced by excess pressure

Question 8.
Distinguish between Active and Extinct volcanoes. Active volcanoes:
Answer:
Constantly eject soild, liquid and gaseous materials. Eg – Mt-Etna and Stromboli of Italy, Mt. Helens of USA.
Extive volcanoes:
Are one’s which have not been active for considerable period of time, and there are no possibilities of future eruption. They are also called ‘dead volconoes’ Eg – Nar condum (Andaman and Nicobar Islands in India). Mt. Helens of USAand Stromboli of Italy.

Question 9.
Name any two countries which come under the Circum- pacific belt.
Answer:

• New Zealand
• The Philippines.

Question 10.
How are igneous rock formed? give examples.
Answer:
Igneous rocks are the primary (first) rocks formed by the action of volcano. They are formed on the surface of the Earth and in the crust by the cooling of lava and Magma. Eg-Basalt, Granite, Diorite.

Question 11.
Distinguish between Arenaceous and Argillaceous rocks.
Answer:

1. Arenaceous rocks: Are rocks formed by sand grains and are porous in nature. Eg-sand stone.
2. Argillaceous rocks: Are rocks formed largly by fine clay particles, non-porous in nature. Eg-shale.

Question 12.
How is contact metamorphism different from regional metamorphism?
Answer:

1. Contact metamorphism: When the hot molten Magma comes to the surface of the earth passing throngh Joints and fissures in the rocks, the rocks that come in contact with the molten magma or lava get baked or burned to form metamorphic rocks. Eg marble from limestone.
2. Regional metamorphism: During the process of Earth movement and mountain building, masses of Igneous and sedimeatary rocks are squeezed and buried deep inside the Earth and are matamorped by the heat and pressuve Eg-slate from clay, Graphite from coals.

Question 13.
Give four examples of Metamorphic rock.
Answer:
Examples of metamorphic rocks

• Granite – Gneiss
• Basalt – Schist
• Sandstone – Quarzite
• Shale – Slate

Question 14.
What are metallic and non-metallic minerals?
Answer:

1. Metallic: are minerals in metallic form or contain metal. Eg- Iron ore
2. Non-metallic: are minerals in non-metal form and do not contain metals Eg-zinc, phosphate, Asbestos.

III. Answer the following.

Question 1.
Explain the structure and composition of the Earth with a neat diagram.
Answer:
Structure and Composition of the Earth.

On the basis of velocity of seismic waves, density of material, chemical compo sition andphysical state of matter the Earth’s interior is divided into three concentric zones viz.,

1. The crust
2. The Mantle
3. The Core

1. The Crust:
The uppermost layer of the Earth is called the Crust. This layer comprises of continental and oceanic regions. The thickness of the crust varies under the oceanic and continental areas. The depth of the crust is 60 km. On the basis of its nature and features the Curst is divided into two layers. They are Continental Crust and Oceanic Crust. The Crust consists of all three major types of rocks such as Igneous, Sedimentary and Metamorphic.

(A) Continental Crust:
This is the uppermost layer ofthe cmst and the Earth. Continental Crust is thicker than the Oceanic Crust. The mean thickness of continental Crust is around 30 km, wereas the Oceanic Crust is around 5km. The Continental Crust is thicker, its maximum thickness is around 60 km beneath mountain ranges. The outer portion of the Crust is known as Sial [silica and aluminium]. It is the lightest layer with the density of 2.7gm.cm Continental Crust is floating on the dense Oceanic Crust.

(B) Oceanic Crust:
The lower part of the Crust is known as Oceanic Crust. Its thickness is around 5 km. This layer is rich in silica and magnesium. Therefore, it is called Sima. The mean density of this layer is 2.95gm/ cm3. Sima forms the ocean floors and is heavier than sial.

The two important discontinuities in the Crust are: a) Conrad discontinuity- between Sial and sima and b) Mohorovicic (Moho) discontinuity- between Crust and Mantle.

2. The mantle:
The portion of the Earth’s interior below the Crust is called Mantle. It extends from 60 km to 2,900km. The density of this layer ranges from 3.3 to 5.7gm/cm3. The materials are in semi liquid or partially molten state due to high temperature known as Magma. The mantle is a composition of dense and rigid rocks which have minerals like magnesium and iron(01ivine). The mantle has two parts:-

(I) Upper Mantle:
This is the outer layer of the Mantle known as asthenosoluric partially in molten condition. Most of the earthquakes and volcanoes take birth due to disorder in this layer.

(II) Lower Mantle:
This is the lower layer of the Mantle known as Mesosphere and it is in solid form. The important discontinuities in the Mantle are:

• Repetti discontinuity-between Asthenosphere and Mesosphere and
• Gutenberg/Oldham discontinuity-between Mantle and Core.

3. The core:
The Core is the inner most layer of Earth. The depth of this layer is up to 6371km from the surface. The most important materials of core are nickel and ferrous (iron). Therefore, it is known as Nife. It is the densest layer with density varying between 5.5 and 11 gm/ cm3.
(a) Outer Core:
It is the outer layer ofthe Core consisting ofhard molten rocks. Most ofthe materials are in molten form. It extends from 2900km to 4980km.

(b) Inner Core:
It is the lower layer ofthe Core with very high temperature and pressure. Most ofthe materials are in solid form. Therefore, it is called solid core. The average temperature of this layer is around 2900° C. This layer lies between the depth of4980 and 6371km. Lehmann/Bullen/Transition discontinuity is found between Outer Core and Inner Core.

Question 2.
What is an Earthquake? Describe the causes and effects earthquake.
Answer:
Earthquake is a natural hazard and disaster that takes place due to sudden movement and disturbance in the rocks in the interior ofthe Earth. They are movements within the Earth caused by natural are Man-made stresses. It is a sudden vibratiomor Oscillation in the crust of the earth.

It is a form of energy of waves motion transmitted through the surface layer ofthe earth. It is also described as a shock or sudden series of shocks due to sudden movement of crustal rocks. The place of origin of the earthquake in the earth’s crust is called ‘Focus’.

The point on the surface of the earth which is perpendicular to the focus is called ‘Epicentre’. The areas that aurround the Epi-centre are affected by the Earthquake.

Cause the effects of earthquakes:
On the basis of their occurence earthquakes are classified into:
(a) Tectonic earthquake:
Which are caused due to folding, faulting and displacement of rocks of rocks in the Earth’s Crust.
Effects: Tectonic Earth quakes are highly intensive and destructive seismic activities.

(b) Volcanic earthquakes:
are associated with the volcanic activities and are usuually caused at great depths. They are earthquakes of low intensity and magnitude.
Effects: The Destruction and damage are slightly lessser than earthquakes caused by Tectonic Forces.

(c) Earthquake caused by man-made factors:
The over interaction of man on nature such as construction of huge dams, reservoirs, deep mining, underground nuclear explosion etc., cause drastic change in the crustal formation leading to seismic activity. Eg: Koyna dam (India), Hoover dam (USA)

Question 3.
How does a Volcano erupt? Explain the types of Volcanoes.
Answer:
The hot Materials from the interior of the Earth, consisting of gases, hot water, lava and fragments of rocks are ejected through a vent or opening on the surfhce of the earth. The passage through which the earth’s crust through which magma and other volcanic materials are ejected is called ‘Vent’. The funnel shaped hollow at the top of the cone of a volcano is called ‘Crater’. Alarge basin shaped crater bounded by steep sides is know as ‘Caldera’.

1. Active volcano: constantly eject soild, liquid and gaseous materials. Eg: Mt-Etna and Stromboli of Italy, at Helens of US A
2. Extinct volcanoes: are one’s which have not been active for comsiderable period of time, and there are no possibilities of future eruption. They are also called ‘dead volconoes’ Eg.Nar condum (Andaman and Nicobar Islands in India).
3. Dormant volcano: are one’s which become quite after eruption, and show no indications of further eruptions, but erupt again after a long period very violently.

They cause enormous damage to human life and property. Eg. Mt-Vesuvius of Italy, Mt-Fujiyama of Japan and Mt-Karkatau of Indonesia.

Question 4.
What is a rock? Describe the diferent types of rocks.
Answer:
Rocks are solid natural substances formed in the earth’s crust by volcanoes and other natural agents. They are also agents of minerals. A rock may be hard like granite of soft like limestone. They may be porous like sand stone or nonporous like shale. The study of rocks is called ‘Petrology’ The uppermost layer of the earth, ‘Lithosphere’ is formed by rocks.

Types rocks: Rocks are classified based on their formation.
1. Igneous rocks: are classified based on their silica content

• Acid Igneous rocks: have more silica Eg: Granite
• Basic Igneous rocks: have low silica Eg: Gabbor.

Igneous rocks are further classified based on their occurence.

(I) Intrusive Igneous rocks:
are formed below the Earth’s surface or in the crust of the Earth
by the solidification of magma. The two important sub-types of Intrusive Igneous rocks are –

• Plutonic rocks: are deep seated, coarse grain in size, formed by slow cooling of magma at great depth, eg. Granite, Gabbro, Diorite etc.
• Hypabyssal rocks: are formed by fast cooling and solidification of rising magma in the intermediate regions i.e., just beneath the Earth’s surface, eg. Dyke.

(II) Extrusive Igneous rocks:
are formed by cooling and solidification of lava on the surface of the Earth eg. Basalt.
Igneous rocks are hard, compact, massive, non-fossiliferous and crystalline in nature. They do not occur in layer or strata formation Valuable minerals like Iron ore, Manganese ore, Copper, Tin, Bauxite Zinc, Lead etc., are found in this rock.

2. Sedimentary rocks:
The word ‘Sedimentary’ is derived from the Latin word ‘Sedimentum’ whichmeans, ‘Setting’. Sedimentary rocks are formed by the action of wind and water. The accumulation and consolidation of sediments form sedimentary rocks.

These rocks are also known as Stratified rocks, Secondary rocks (formed after Igneous rock) and Aqueous rocks (formed by water). Sedimentary Rocks are classified based on the character of the Material, composition and the process by which they are formed.

They are classifed into theree major types, which are
(A )Mechanically formed sedimentary rocks:
which are formed by the process of weathering, erosion and accumulation of fragments from the preexisting rocks are called mechanically formed rocks Agents like river, wind, waves etc., transport the fragmented materials and deposit them in the bottom of the lake, sea or oceans. The consolidation and cementing of these materials form sedimentary rocks. In this process three types of rocks such rocks

• Arenaceous rocks: formed by sand grains, porous in nature. eg: standstone.
• Argillaceous rocks: formed largely by fine clay particles, non-porous in nature. eg-Shale.
• Rudaceouse rocks: formed by the cementation and consolidation of pebbles and boulders. eg:Breccia and Conglomerates.

(B) Chemically formed sedimentary rocks:
are formed by the accumulation and cementation of sediments by chemical action. eg-Gypsum, Rock salt, Quartz etc.,

(C) Organically formed Sedimentary rocks:
are formed by the decay and decomposition of vegetation and skeletal remains of animals, which are two types.

• Calcareous rocks: formed by the skeletal remains of certain animals, which are rich in calcium eg: Limestone.
• Carbonaceous rocks: formed by the decay and decomposition of plants, trees and vegetation, which are rich in carbon eg: Coal. .

Sedimentary rocks are in strata or layer form, usally porous, contain fossils, formed from the pre-existing rocks, non-crystalline in nature found in the largest surface area of the Earth. Minerals like Coal, petroleum, Natural gas, Sandstone, Clay, Limestone are found in this rock.

3. Metamorphic rocks:
Metamorphic means ‘change of form’. When the Igneous and Sedimentary rocks undergo physical and chemical changes due to the influence of temperature and pressure, it results in the formation of Metamorphic rocks. Metamorphism is the process in which original rock becomes harder and the mineral content also undergoes transfomation.
The Process of Metamorphism is of two types:
(a) Contact Metamorphism:
which deirectly related to the volcanic activity. When the hot – molten magma comes to the surface of the Earth, it passes through joints and fissures in the rocks. The rocks coming in contact with the magma or lava get baked or burnt to form Metamorphic rock. It is also known as Thermal or Local metamorphism. eg-Marble from Limestone.

(b) Regional Metamorphism:
is associated with Earth movements and processes of mountain building.. In this the masses of Igneous and Sedimentary rocks are squeezed and buried deep in the Earth. The heat and pressure causes metamorphism on these rocks, eg: Slate from clay, Graphite from coal.

Metamorphic rocks are compact, hard and do not contain fossils A few precious minerals and gem stones like Diamond, Gold ore, Marble, Quartzite, Ruby, Emerald, Sapphire are found in metamorphic rock.

Question 5.
What is a mineral? Explain the types of minerals.
Answer:
Minerals: Mineral is a natural inorganic substance which has certain chemical and physical properties. Eg- Feldspar, Quartz, Mica.
Types of Minerals:
Minerals are classified based on their nature, texture and uses.

1. Metallic Minerals: are in Metallic form or contain metal. Eg-from ore, Manganese ore, Bauxite, Copper ore.
2. Non-Metallic Minerals: are not in metallic form and do not contain metal. Eg- Mica, Asbestos, sulphur, Lead, Zinc, Phosphate.
3. Ferrous minerals – Contain Iron (ferrous) eg-Iron ore.
4. Non-ferrous minerals- do not contain ferrous eg-Bauxite, Mica.
5. Precious minerals – used for making decorative, commercial and precious ornaments. Eg- Gold, Platinum, Diamond, and Silver.
6. Nuclear or Atomic minerals- used for generation of Nuclear Energy. Eg- Uranium, and Thorium.

Activities

List out the deepest mines and places of India and the world.

1. Deepest mines in India:
Kolar Gold Fields (Kolar) – deepest gold mine in India and second deepest gold mine in the world. Chenakrui coal mines (Open Cast)

2. List of deepest mines in the world:

• Anglo Gold Asharti’s Mponeng gold mine – Johannesburg, south Africa 3.9km deep.
• Tau Tona, Anglo Gold Ashanthi’s Gold mine, west-wits, south Africa. Second deepest mine in the world.
• Savulea Gold mine, west wits, south Africa 3.7 km Deep Dricfontcin mine, Carletion ville, South Africa 3.4km deep
• Kirsasalethu Gold mine, Johannesbury, Ganteng, South Africa 3,276m deep.
• Kidd creek copper/Zinc Mine Timmins, Ontario, canda eight deepest mine -2,927m deep.
• Creighton nickle mine – Sudbury, Canada 2.5 km deep tenth deepest mine.