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

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

You can Download Chapter 3 Interior of the Earth Questions and Answers, Notes, 1st PUC Geography Question Bank with Answers Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.

1st PUC Geography Interior of the Earth One Mark Questions and Answers

Question 1.
What is Continental Crust? (T. B. Qn)
Answer:
This is the uppermost layer of the crust and the earth. The mean thickness of Continental Crust around 30km.

Question 2.
Name the discontinuity found between Mantle and Core. (T. B. Qn)
Answer:
Gutenberg/Oldham discontinuity found between Mantle and Core.

Question 3.
Why the inner core is called ‘solid core’? (T. B. Qn)
Answer:
It is the lower layer of the Core consisting of hard molten rocks. Most of the materials are in molten form.

Question 4.
Mention the three major layers of the interior of the Earth.
Answer:
The three major layer of the interior of the Earth are the crust, the mantle and the core.

Question 5.
What is the crust?
Answer:
The outer or upper most thin and lightest layer of the earth is the crust.

Question 6.
What are the two layers of the lithosphere?
Answer:
Sial and Sima are layers of the lithosphere.

Question 7.
Where is Mohorovicic discontinuity?
Answer:
It is a boundary that separates the earth’s crust and the mantle.

Question 8.
Which layer is called pyrosphere?
Answer:
The layer lies in between the crust and the core of the earth is known as pyrosphere. It begins from Mohorovicic discontinuity and continues up to a depth of Gutenberg discontinuity.

Question 9.
What is Nife?
Answer:
The inner core of the barrysphere is called ‘Nife’ as it consists of Nickel and Ferrous (Iron).

Question 10.
Where is Gutenberg discontinuity?
Answer:
The boundary that separates the mantle from the core is known as ‘Gutenberg Discontinuity’.

Question 11.
Which zone is called as Mantle zone?
Answer:
The Pyrosphere is also called Mantle zone.

Question 12.
Which zone is called Core?
Answer:
The zone of Barrysphere is called as Core. It is the innermost layer of the earth.

Question 13.
What is Sima?
Answer:
The lower part of the earth’s crust is named as ‘Sima’ As it consists of Silica and Magnesium.

Question 14.
What is sial?
Answer:
The outer portion or top layer of the crust is made up of granite rocks in which silica and aluminum elements predominate is known as Sial.

Question 15.
Name the instrument used to record seismic waves. (T. B. Qn)
Answer:
Seismograph is used to record seismic waves.

Question 16.
Which is the most destructive earthquake wave? (T. B. Qn)
Answer:
Surface waves (long period waves) are most destructive earthquake wave.

Question 17.
Define Tsunami. (T. B. Qn)
Answer:
A large sea wave occasionally experienced along the sea coast caused by an underwater or sub-marine earthquake is called Tsunami.

Question 18.
What is Homo-seismal line? (T. B. Qn)
Answer:
Lines drawn on the map to show the places recording the same time of occurrence of earthquake.

Question 19.
Mention the region which record more seismic activities in the world. (T. B. Qn)
Answer:
The Circum-pacific belt record more seismic activities in the world.

Question 20.
What are the three concentric zones of the earth?
Answer:
Lithosphere, Pyrosphre and the core are the three concentric zones of the earth.

Question 21.
What do you mean by Seismology?
Answer:
The science of study of earthquakes is called seismology.

Question 22.
What is iso-seismal line?
Lines drawn on the map to show the places experiencing the same intensity of earthquake.

Question 23.
What is Homo-seismal lines?
Answer:
Lines drawn on the map to show the places experiencing the same time of occurrence of earthquakes.

Question 24.
Mention the two scales of earthquakes.
Answer:

• Richter scale
• Mercalli Scale

Question 25.
What is co-seismal line?
Answer:
Lines drawn on the map to show the places experiencing same intensity and same time of occurrence of earthquake.

Question 26.
Which zone is called ‘Zone of fracture’?
Answer:
The mid-continental belt.

Question 27.
Which waves are called transverse waves
Answer:
Secondary waves.

Question 28.
Which zone is called Core
Answer:
The zone of Barrysphere is called as Core.

Question 29.
Who is ‘Seismologist’?
Answer:
The Person who is specialized in the study of earthquakes are called Seismologist.

Question 30.
Which waves are called ‘transverse’ waves?
Answer:
Secondary waves are called transverse waves.

Question 31.
What is Earthquakes?
Answer:
It means Vibration of the earth crust. The shaking or sudden vibration or series of vibrations are resulted from sudden movements of the earth’s crust.

Question 32.
What is seismograph?
Answer:
An instrument devised to record and measure the intensity of earthquake is known as ‘seismograph’.

Question 33.
What is Seismogram?
Answer:
It is the science which studies various aspects of seismic waves generated during the occurrence of earthquakes.

Question 34.
Where are the seismograph Stations established in India?
Answer:
In India, the seismograph centers are located at Kodaikanal (T.N), Poona, Kolaba (Maharashtra) Kolkata (W.B) and Gowribidnur (Karnataka).

Question 35.
Who and when postulated the elastic rebound theory?
Answer:
Elastic rebound theory was propounded by Harry Fielding Reid, and American Geologist in 1911.

Question 36.
What are the Tsunamis?
Answer:
These are the waves of greater height produced by the earthquakes in the oceans. Tsunami is a Japanese term. Tsu means port and nami means waves. Thus waves approaching the port are called Tsunamis.

Question 37.
Mention the waves of Earthquakes?
Answer:
There are three major waves

1. Primary waves (P)
2. Secondary waves (S) and Surface waves (L).

Question 38.
What is Focus?
Answer:
The place of the origin of an earthquake in the earth’s crust is called focus

Question 39.
Which earthquake belt is known as zone of fracture?
Answer:
The Mid- continental belt.

Question 40.
What is Epicenter?
Answer:
The point where the earthquake waves or shock waves reach the surface for the first time is called epicenter.

Question 41.
Which waves of earthquakes are highly destructive?
Answer:
The surface waves or Long wave are most destructive as they vibrate much.

Question 42.
Who invented the Richter scale?
Answer:
Charles Richter of U.S.A in invented Richter scale in 1935.

Question 43.
Mention the region which record more seismic activities in the world. (T. B. Qn)
Answer:
The Circum-pacific belt record more seismic activities in the world.

Question 44.
What is Volcano? (T. B. Qn)
Answer:
A volcano is an opening in the crust of the Earth through which heated materials consisting of gases, hot water, lava and fragments of rocks are ejected from the interior of the Earth.

Question 45.
Name any one volcano of India. (T. B. Qn)
Answer:
Narcondam in Andaman & Nicobar Islands is also an important volcano of India.

Question 46.
Which Volcano is called ‘Lighthouse of the Mediterranean’?
Answer:
Stromboli is known as ‘Lighthouse of the Mediterranean’.

Question 47.
What is ‘Volcanology’?
Answer:
The scientific study of volcano is known as ‘Volcanology’

Question 48.
What is ‘Ring of Fire’?
Answer:
The circum-pacific belt is also called Pacific ‘Ring of Fire’. This belt experiences greater number of volcanoes.

Question 49.
State the derivation of the term volcano.
Answer:
The word volcano is derived from a hill located in the island ‘Volcano’ north of Sicily.

Question 50.
What is Vent?
Answer:
Vent refers to the passage in the earth’s crust through which lava and other volcanic materials are ejected. The vent, generally, occurs in the weaker part of the earth’s crust.

Question 51.
What is crater?
Answer:
A typical volcano is a cone-shaped hill with a pit like opening at the top. This opening which acts as the mouth of the volcano is called a crater.

Question 52.
What is Cone?
Answer:
Volcanic materials are ejected through the mouth of the volcano. The ejected volcanic materials accumulate around the vent, and give rise to the volcanic cone.

Question 53.
What is an active volcano?
Answer:
Volcanoes which erupts frequently even now as known as “active volcanoes”. E.g. Mt. Etna in Sicily, Stromboli inLipati islands. Paricutin in Mexico, Cotopaxi in Andes etc. There are about 500 active volcanoes all over the world.

Question 54.
What are the two types of lava?
Answer:
Basic lava and Acidic lava are the two types of Lava.

Question 55.
What is Basic lava?
Answer:
It is composed of iron and magnesium, black inn colour and highly fluid, when it is poured out from the volcano, it flows for a long distance and forms

Question 56.
Where is the only active volcano in India?
Answer:
Barren and Norcondom Island located to the northeast of port Blair of Andaman Islands.

Question 57.
What is Acidic lava?
Answer:
Acidic lava is highly viscous, contains high percentage of silica. If flows slowly and solidifies quickly. Hence deposition occurs only around the craters with steep slopes called domb shaped volcano.

Question 58.
What is Ash cone?
Answer:
A cone-shaped hill formed by of volcanic ash that is built up around a volcanic vent is called ash cone.

Question 59.
Which volcanoes are called “Super Volcanoes?
Answer:
Mt. Vesuvius, Mt. krakatau and Mt. Pelean Volcanoes are called ‘Super Volcanoes.

Question 60.
What is volcanic Spine?
Answer:
The acid lava, which is vicious, solidifies quickly and blocks the vent. This stands up as a steep-sided cone called spine or plug.

Question 61.
What is Geyser?
Answer:
A Geyser is a hot spring form which a column of hot water and stream are alternatively ejected to a great height.

Question 62.
What is laccolith?
Answer:
Laccolith is a large mound of igneous rock formed along a bedding plane in the sedimentary rock layers.

Question 63.
What is Batholith?
Answer:
Batholith is a very large dome -shaped intrusion of igneous rock. It is exposed to the surface only after considerable erosion.

Question 64.
What is lava plateau?
Answer:
An extensive elevated land made up of depositional lava called lava plateau.

Question 65.
What are solid Materials?
Answer:
Volcanic bombs, dust, pumice, Scoria, Volcanic ash, cinder and rock fragments.

Question 66.
What are extrusive landfoms?
Answer:
landforms are formed by the accumulation and solidification of lava and other material ejected by volcanoes eg: volcanic cones, crater etc.

Question 67.
Define petrology. (T. B. Qn)
Answer:
The Scientific study of rocks is called‘Petrology’.

Question 68.
Give an example for plutonic rock.(T. B. Qn)
Answer:
Granite, Gabbro, Diorite is the example for plutonic rock.

Question 69.
Why secondary rocks are called aqueous rocks? (T. B. Qn)
Answer:
Secondary rocks are called aqueous rocks because these rocks are formed by water.

Question 70.
How is carbonaceous rock formed? (T. B. Qn)
Answer:
These rocks are formed by the decay and decompositions of plants, trees and vegetation, which are rich in carbon e.g. Coal.

Question 71.
What is Metamorphism? (T. B. Qn)
Answer:
The process of transformation of rocks from one type to another under conditions of high temperature and pressure is known as Metamorphism.

Question 72.
What is a mineral? (T. B. Qn)
Answer:
Mineral is a natural inorganic substance which has certain chemical and physical properties.

Question 73.
Which mineral covers largest area of the Earth’s crust? (T. B. Qn)
Answer:
Feldspar and silica covers largest area of the Earth’s crust.

Question 74.
Give an example for non-ferrous mineral. (T. B. Qn) ‘
Answer:
Bauxite, mica

Question 75.
Which rocks associate with fossils? (T. B. Qn)
Answer:
Sedimentary rocks are associate with fossils.

Question 76.
What is .an Intrusive rock?
Answer:
Intrusive rocks are formed by the cooling of the magma deep inside the crust of the earth and its solidification under great pressure.

Question 77.
Which type of rocks marble is an example?
Answer:
Metamorphic rocks are the example of Marble.

Question 78.
Which type of rock sand stone is an example?
Answer:
Sand stone is an example of metamorphic rocks.

Question 79.
Which type of rocks basalt in an example?
Answer:
Basalt is the best example of volcanic igneous rocks.

Question 80.
In which type of rocks coal and petroleum reserves are found.
Answer:
Coal and Petroleum reserves are found in Sedimentary rocks.

Question 81.
What are the metamorphic rocks?
Answer:
The rocks that have been changes either in form or compositions without disintegration are called metamorphic rocks.

Question 82.
What are Sedimentary rocks?
Answer:
The rocks which are formed due to aggregation and compactness of sediments are known as “Sedimentary rocks.”

Question 83.
What are Plutonic rocks?
Answer:
The rocks which are formed due to cooling of magma at great depth inside the earth are called Plutonic igneous rock’s.

Question 84.
Which rock is known as Stratified rocks?
Answer:
Sedimentary rocks are also known as Stratified rocks and Secondary rocks.

Question 85.
What are arenaceous rocks?
Answer:
These are formed mainly due to deposition, commentating and consolidation of sane grains e. g. Sand stone.

Question 86.
What are argillaceous rocks?
Answer:
These rocks are formed largely by fine clay particles e.g. Shale or mudstone these are impermeable.

1st PUC Geography Interior of the Earth Two Marks Questions And Answers

Question 1.
Mention any two features of Oceanic Crust. (T. B. Qn)
Answer:
The lower part of the Crust is known as Oceanic crust. It s thickness is around 5 Km. this layeris rich in silica and magnesium. The mean density of this layer is 2.95gm.

Question 2.
Why Mantle is very important in the Earth’s interior? (T. B. Qn)
Answer:
The portion of the Earth’s interior below’ the Crust is called mantle. It extends from 60 km to , 7,900km. The density of this layer ranges from 3.3 to 5.7gm.The mantle is a composition of dense and rigid rocks which have minerals like magnesium and iron.

Question 3.
What is Mantle?
Answer:
The portion of the earth’s interior, lying beneath the crust and above the core, is known as the mantle. It is largely made up of basic silicates, rich in iron and magnesium. It extends to a depth of 2,900 kms of inside the earth

Question 4.
What is lithosphere?
Answer:
The outer most part of the earth or the crust is known as Lithosphere. It forms only 0.5 percent of the total volume of the earth. The thickness of the crust varies from 10 to 60km. It consists of all the three major types of rocks, such as Igneous, sedimentary, and metamorphic rock.

Question 5.
What is Pyrosphere?
Answer:
This layer lies n between the crust and the core of the earth. It begins from Mohorovicic discontinuity and continues up to a depth of2900km where ‘Gutenberg discontinuity’ separates the central core form the pyrosphere. It constitutes about 16percent of the total volume of the earth. The specific gravity of pyrospehre varies at different depths, generally it increase towards the central core. The Pyrosphere is also called Mantle zone.

Question 6.
What is Isostacy?
Answer:
One interesting property of the continental and oceanic crust is that these tectonic plates have the ability to rise and sink. This phenomenon, known as isostacy, occurs because the crust floats on top of the mantle like ice cubes in water. When the Earth’s crust gains weight due to mountain building or glaciations, it deforms and sinks deeper into the mantle if the weight is removed, the crust becomes more buoyant and floats higher in the mantle.

Question 7.
What is Barysphre?
Answer:
It is the inner most layer of the earth. It extends from Gutenberg discontinuity to the central point of the earth and has a thick mass of about 3478 Km. It consists about 83% of the total volume of the earth. It is a spherical zone extending from 2900 km to 6378 km. The core of the earth is also divided into two layers namely outer core and inner core.

Question 8.
State the difference between Focus and Epicenter. (T. B. Qn)
Answer:
The point in the interior of the Earth from where the earthquake tremors originate is called the seismic focus. Earthquake tremors move from the focus in all directions. The point o the Earth’s surface vertically above the focus is called the epicenter. The Earthquake is felt first at the epicenter.

Question 9.
Name any two causes for earthquakes. (T. B. Qn)
Answer:
Folding, Faulting, volcanic activity, landslides are the major causes for earthquakes. Earth quakes are also caused by human activities such as mining, nuclear explosion.

Question 10.
Distinguish between Iso-seismal and Co-seismal lines. (T. B. Qn)
Answer:
Lines drawn on the map to show the places experiencing the same intensity of earthquake are called Iso-seismal lines. Lines drawn the map to show the places experiencing same intensity and same time of occurrence of earthquake are called Co-seismal lines.

Question 11.
Which scales are used to measure the intensity of an earthquake? (T. B. Qn)
Answer:
To measure the intensity and magnitude of the earthquakes two scales are sued There are Richter scale and Mercalli Scale.

Question 12.
What is a volcanic earthquake?
Answer:
These are associated with the activity of volcanoes and occur as a result of depth explosion of the gases and magma. Such volcanoes are confined to volcanic areas. The intensity of such earthquakes depends on the intensity of volcanic eruption. They are not very destructive e.g. Krakatau (1883) and Katmai (1912).

Question 13.
What are Tectonic earthquakes?
Answer:
These are caused due to faulting, folding and displacement of blocks of the (lithosphere) crust. Due to some structural activity, earth stresses are produced. These stresses build up a fracture, the rock masses on either side on the fracture get displaced and the strain is released. AH major earthquakes are said to be of tectonic origin and are very disastrous. E.g. Koyna (1907) Quetta (1935).

Question 14.
What are Collapse earthquakes?
Answer:
These are associated with the processes of falling of rocks and avalanches in mountain, large landslides, and the collapse of natural caves and so on. These earthquakes are confined to earth’s surface and constitute only a small number of the total earthquakes.

Question 15.
What is Tectonic force?
Answer:
Such as faulting, breaking of rocks, raising or sinking of the layers of the earth Folding, of the strata or vapour trying to come out from beneath the earth.

Question 16.
What is volcanic force?
Answer:
Violent eruptions and extrusion of igneous magma from below the earth. Volcanic earthquakes are caused by gas explosions or the undoming and fissuring of volcanic structures. Such earthquakes bccur either simultaneously with eruptions or more commonly in the period preceding an eruption.

Question 17.
What are surface waves?
Answer:
These are the slowest waves and reach the Epicentre at the Last stage. Surface waves are also called ‘Long’ waves of ‘Long period’ waves. The speed of these waves is around 3 to4 km per second and are confined to the upper layer of the crust. These waves cause heavy destruction and damage on the crust of the Earth.

Question 18.
Mention any two causes of a volcano. (T. B. Qn)
Answer:
The temperature inside the Earth increases with the increasing depth (1°C per 32m) Formation of magma because of increase in temperature and reduction in pressure.

Question 19.
Distinguish between Active and Extinct volcanoes. (T. B. Qn)
Answer:
Active Volcanoes are those volcanoes which erupt regularly or frequently e.g. Mt. Etna in Sicily and Stromboli of Italy, Mauna Loa. Extinct volcanoes are volcanoes which have not been active for considerable period of time .There are no possibilities of future eruption in these volcanoes. These volcanoes are also called Sleeping or Dead volcanoes. Narcondum, Vesuvius and Krakatoa are examples of extinct volcanoes.

Question 20.
Name any two active volcanoes of the world. (T. B. Qn)
Answer:
Mauna Lopa and Mauna Kea of Hawaiian Islands, Cotopaxi and Chimborazo of Ecuador Mt. Etna and Stromboli of Italy, St Helens of USA.

Question 21.
Name any two countries which come under the Circum-pacific belt. (T. B. Qn)
Answer:
Japan, USA, Hawaiian Islands, Philippines, Alaska, New Zealand.

Question 22.
How are Igneous rock formed? Give examples. (T. B. Qn)
Answer:
The word ‘Igneous’ is derived from the Latin word ‘ignis’ meaning fire. These rocks are primary rocks formed by the cooling, solidification and crystallization of magma.
On the basis Silica content, igneous rocks are classified as

• Acid igneous rocks: Granite
• Basic igneous rocks: Gabbro.

Question 23.
What are dormant volcanoes?
Answer:
Dormant volcanoes are those volcanoes which have remained inactive for a long period of time, but may erupt in the future e.g. Mt Fuiyama in Japan.

Question 24.
What is Extinct Volcanoes?
Answer:
Extinct volcanoes are volcanoes which will most probably not erupt again in the future. Vesuvius and Krakatoa are example of extinct explosions. Popa in Myanmar (Burma) also is an example of extinct volcano.

Question 25.
What are intermediate volcanoes?
Answer:
Some of the volcanoes are characterized with both explosive and tranquil eruptions. These are intermediary volcanoes as they are named after their mode of eruption. Since the materials thrown out are different, they posses both the qualities. Some time solid fragments are thrown with explosion, whereas sometimes only lava flows out silently. As such the slope of the hills formed with the deposition is also of intermediately.

Question 26.
What is Cinder Cone?
Answer:
The erupted solid particles consist of large rock fragments as well as small angular rock pieces. Cinder as they are called is deposited around the vent to form cinder cone.

Question 27.
Which is highest Volcanic Mountain the world?
Answer:
OJOSS del Salado, 6891 meters located between Argentine and Chile boundary, in of South America is the highest Volcanic Mountain in the world (Andes Mountain).

Question 28.
What is Hot springs?
Answer:
Hot springs or thermal spring’s are more common. The water sinks deep inside where the rocks are heated. The heated water rises to the surface without any explosion. Such springs contain dissolved minerals which are of medicinal value. They can be also used to generate electricity. Iceland has thousands of hot springs.

Question 29.
What is Lava dome?
Answer:
The shape of lava dome is determined by the nature of lava. The highly fluid basic lava builds up shield dome with gently rising slopes, and flattened top. The basic lava, which is highly viscous, builds up dome with a great height and steep slope.

Question 30.
What are Intrusive Land forms?
Answer:
Intrusive land forms occur when lavas solidified within the earth’s crust and gives rise to various shapes or forms intrusive landforms are formed along the bedding planes of sedimentary rocks.

Question 31.
What is Dyke?
Answer:
The Magma from the interior of the earth finds its way towards the surface through a passage. When it is able to reach the surface, it cools and solidifies, and a vertical or highly inclined feature is formed, and such a features is called dyke.

Question 32.
What is Hot springs?
Answer:
Hot springs or thermal spring’s are more common. The water sinks deep inside where the rocks are heated. The heated water rises to the surface without any explosion. Such springs contain dissolved minerals which are of medicinal value. They can be also used to generate electricity. Iceland has thousands of hot springs

Question 33.
What is composite cone?
Answer:
A volcanic cone composed of alternative layers of ash, cinder and lava is called composite cone. This results from the accumulation of materials over a long period of time from a number of eruptions. This type of cone is the most common volcanic feature. Fujiyama of Japan and Mt. Etna of Sicily are examples of this type of cone.

Question 34.
What is volcanic crater?
Answer:
The opening of the volcano through which materials are throughout is known as a crater. It is a funnel shaped hollow at the top. Sometimes in the explosive volcanoes the peak of the volcano is blown up to form a caldera.

Question 35.
How are Igneous rock formed? Give examples. (T. B. Qn)
Answer:
The word ‘Igneous’ is derived from the Latin word ‘ignis’ meaning fire. These rocks are primary rocks formed by the cooling, solidification and crystallization of magma. On the basis Silica content, igneous rocks are classified as

• Acid Igneous rocks: Granite
• Basic igneous rocks: Gabbro.

Question 36.
Distinguish between Arenaceous and Argillaceous rocks. (T. B. Qn)
Answer:
Arenaceous rocks are formed when grains of coarse or fine sand are cemented together. They are porous, and can hold water, e.g. Sand stone Argillaceous rocks are consist mostly of fine clay which gets hardened and forms shale or mudstone, e.g. Shale.

Question 37.
How is contact metamorphism different from regional metamorphism? (X. B. Qn)
Answer:
Contact metamorphism is directly related to the volcanic activity. When the hot molten magma comes to the surfaced 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. E.g. Marble from Limestone. Regional metamorphism is associated with Earth movements and processes of mountain building. In this the masses of Igneous and Sedimentary rocks are squeezed and buribd deep in the earth. E.g. Slate from Clay, Graphite from Coal.

Question 38.
Give four examples of metamorphic rock. (T. B. Qn)
Answer:
Marble, Diamond, Quartzite, Ruby, Emerald are the examples of metamorphic rock.

Question 39.
What are metallic and non-metallic minerals? (T. B. Qn)
Answer:
Metallic Minerals are the minerals in metallic form or contain metal. Few metallic minerals are Iron ore, Manganese ore, Copper ore etc.
Non-metallic minerals are not in metallic form and they do not contain metal. E.g. Mica, Sulphur, Lead, Zinc, Phosphate etc.

Question 40.
What is Rock cycle?
Answer:
The rock cycle is a general model that describes how various geological processes create, modify, and influence rocks This model suggests that the origin of all rocks can be ultimately traced back to the solidification of molten magma. Magma consists of a partially melted mixture of elements and compounds commonly found in ‘rocks. Magma exists just beneath the solid crust of the Earth in an interior zone known as the mantle.

Question 41.
Mention the types of sedimentary rocks?
Answer:
Based on Origin and composition sedimentary rocks are divided into three types

1. mechanically formed rocks.
2. Chemically formed rocks.
3. Organically formed rocks.

Question 42.
What are hypabyssal rocks?
Answer:
These are intermediate rocks between the extruded volcanic rocks and the deep plutonic rocks. They are formed due to cooling and solidification of magma in cracks, pores, crevices etc.

Question 43.
What are Extrusive Rocks?
Answer:
The rock which are formed by the cooling and solidification of magma or lava on the surface of the earth re known as “Extrusive Igneous rocks”. These rocks are also called volcanic rocks, as they are formed during volcanic eruption. No crystals are formed in these rocks due to rapid cooling of lava; basalt is typical example of this kind of rock. ‘

Question 44.
Mention the characteristics of igneous rocks?
Answer:
The chief characteristics of igneous rocks are.

• Igneous rocks are associated with volcanic activities.
• They are compare and massive
• They do not have stratas and are not porous.
• They are crystalline and do not contain any fossils.
• They are quite hard and resistant to weathering and erosion.
• They contains metallic minerals
• Suitable for construction purpose
• They re very valuable minerals in recent years.

Question 45.
What are Calcareous rocks?
Answer:
Calcareous rocks are formed mostly from the remains of living organisms. These rocks contain calcium carbonate or lime. They include limestone and chalk. They are porous and soluble.

Question 46.
What is Metamorphism?
Answer:
The process of transformation of rocks from one type to another under the conditions of high temperature and pressure is called Metamorphism. The word metamorphism is derived from the term ‘Metamorphose’ means change in form.

Question 47.
What are carbonaceous rocks?
Answer:
These are formed due to the transformation of vegetative matter. Under the impact of heat and pressure the remains of plants are turned into hard layers. E.g. coal.

Question 48.
What is a sedimentary rock? Why it is called aqueous rocks?
Answer:
The rocks which are formed due to aggregation and compactness of sediments are known as “Sedimentary rocks.” These are formed by the deposition of sediments derived form older rocks, plants and animal remains by rivers, winds, glaciers etc. These sediments are hardened into rocks by pressure. Most often, they are formed on the bed of shallow seas or lakes and so they are called aqueous rocks.

Question 49.
What are Rudaceous rocks?
Answer:
These are formed due to cementation and consolidation of pebbles and boulders e.g. Conglomerate and breccias. When large rounded pebbles are firmly cemented to form rocks they are known as conglomerate. When the rock fragments are angular and cemented together to form rocks. They are called breccias. These are porous rocks.

Question 50.
What is a Mushroom Rock? How is it formed?
Answer:
The rocks having broad upper part and narrow base resembling an umbrella or mushroom are called Mushroom Rocks. These are formed due to abrasive work of wind.

Question 51.
Describe the work of river in the upper and middle course.
Answer:
The work of running water in the form of surface runoff or overland flow and streams is most important of all the exogenesis or plantation process e.g. ground water, sea waves, glaciers, wind etc. Because the running water is the most widespread exogenesis process on this plant earth.

1st PUC Geography Interior of the Earth Five Marks Questions And Answers

Question 1.
Explain the structure and composition of the Earth with a neat diagram.(T.B.Qn)
Answer:
On the basis of the physical and chemical properties of the earth’s surface, behavioral patterns of seismic waves of earthquakes and the lava erupted form volcanoes, it is generally held that the earth is composed of three layers or parts.

1. The crust: The outer or upper most layer of the earth is the crust. It is solid and is the thinnest and lightest part. It is 6to 60 kms thick. It has two layers.
a. Continental crust or sial: The upper part consist of sedimentary and granite rocks’ and forms the continents. Its major constituent elements are silica and aluminum. So, it is termed as sial. Its average thickness ranges between 10-12 km.

b. Oceanic crust or Sima: The lower part of other 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 lower continuous layer is mostly composing of silica and magnesium and so it is termed as sima. The mean density of this layer is 2.95gm. Conrad discontinuity between Sial and Sima and Mohorovicic discontinuity between Crust and Mantle are the major discontinues in the crust.

2. The Mantle: The portion of the earth’s interior, lying beneath the crust and above the core is known as mantle. It is largely made up of basic silicates, rich in iron and magnesium. It extends from 60 to 2,900km. The density of this layer from 3.3 to 5.7gm. The mantle has two parts.

a. Upper Mantle: This is the outer layer of the Mantle known as Asthenosphre. Most of the earthquakes and volcanoes take birth due to disorder in this layer.

b. Lower Mantle: This is the lower layer of the Mantle known as Mesosphere and it is in solid form. Repetti discontinuity between Asthenosphere and Mesosphere and Gutenberg discontinuity between Mantle and Core are the major discontinues in the mantle

3. The core: The core is the central part of the earth’s interior. It extends from the lower boundary of the mantle to the centre of the earth for about 6,400 kms. The most important materials of core are nickel and ferrous (Nife). The core consists of two layers, namely.

a. Outer core: It is the outer layer of the Core consisting hard molten rocks. Most of the materials are in molten form. It extends from 2900km to 4980km.

b. Inner core: It is the lower layer of the Core with very high temperature and pressure. Most of the materials are in solid form therefore, it is called solid core. The average temperature of this layer is around 2900° C. Transition discontinuity is found between Outer. Core and Inner Core.

Question 2.
What is an Earthquake? Describe the causes and effects of earthquake. (T.B.Q)
Answer:
An Earthquake is a sudden vibration or oscillation in the Crust of the Earth. It is a form of energy of wave motion transmitted through the surface layer of the Earth. The place of origin of an Earthquake in the Earth’s crust is called ‘Focus’. The point on the Earth surface which is perpendicular to the focus, receiving seismic waves is called ‘Epicentre’.

Causes of Earthquake: On the basis of occurrence earthquakes can be classified into three types. They occur due to several causes such as tectonic forces, folding, faulting, volcanic eruptions landslides, avalanches, man-made factor.

Tectonic Earthquakes: These are caused due to folding, faulting and displacement of blocks of rocks in the Earth’s crust. They are highly intensive and destructive seismic activities.

Volcanic Earthquakes: These are associated with the volcanic activities and are usually caused at great depths. They are with low intensity and magnitude. The destruction and damage are slightly lesser than earthquakes caused by Tectonic forces.

c. Earthquakes caused by man-made factors: Over interaction of man underground nuclear explosion etc, are causing great change in the crustal formation leading to seismic activity. E.g. Koyna dam (India)-1967, Hoover dam (U.S.A)-l 935, Mangladam (Pakistan). Effects of Earthquakes: Earthquakes cause violent disturbances and widespread damage and destruction, especially on the epicentre region.

• Earthquakes cause changes in the earth’s surface. Cracks and fissures develop in the earth’s crust.
• Vibrations, caused by earthquakes, lead to landslides in mountainous regions, damming the rivers.
• vertical or horizontal cracks are formed, and the land is elevated or lowered, forming lakes.
• Deep cracks may be developed in dams after the earthquake. For instance, deep cracks were developed in the Koyna dam after the earthquake.
• The beds of rivers may be raised by the earthquakes. For example, the bed of the river Brahmaputra was raised during the Assam earthquakes.
• here is the greatest danger of falling of houses, roads railway lines factories, bridges, dams, aerodromes, and other man-made structures, resulting in loss of life and property.
• The underground water system is disturbed.

Question 3.
Explain the distribution of Earthquakes.
Answer:
No part of the earth is free from the quakes. But their frequency of occurrence and intensity varies. On the surface of the earth hundreds of quakes of different intensity are recorded every year.
The earthquakes distribution is grouped into 5 major belts they are:

1. Circum-pacific Belt: This belt includes the Rockies of North America, Andes of South America and the island of East Coast of Asia, U.S.A, Chile, Peru, Alaska, Japan and Indonesia. This belt has high frequency of earthquakes of very high magnitude.
2. The extensive ocean basic of the Pacific Ocean is seismically highly active
3. The Alphs-Himalayan fold mountain region. It comprises Southern Europe, North Africa, Central Asia, Northern Mountain region of India. This belt is known as “Zone of fracture’.
4. The Mid oceanic ridges of Atlantic and Indian Ocean.
5. The longitudinal Rift valley of East African Coast which run north to south for several thousand kilometers.

Question 4.
Explain the Earthquake waves?
Answer:
The earthquake waves based on their mode of traveling and velocity are broadly classified into three types. They are,

1. Primary (P) waves
2. Secondary (S)waves
3. Surface (L) waves

1. Primary (P) waves: These are also known as Push waves or waves of compression. The particles vibrate in the direction of the movement of the wave, similar to a sound wave. They can travel through solid, liquid and gases. The velocity varies from 5.5 to 13 km per second depending on the medium of their travel they are the first to be recorded in the epicenter by the seismograph.

2. Secondary (S) waves: They are recorded on a seismogram after the P) waves. These are also called traverse or shake waves (S). These are distortional waves as the particles vibrate at right angles to the direction of the movement of the waves. The velocity of the secondary waves varies form 3 to 7 kms per second. They can travel through the interior and outer layer of the earth but cannot be transmitted by liquids.

3. Surface waves: These are also described as Long waves (L). The ‘L’ waves travel along the surface of the earth and are recorded after ‘P’ and ‘S’ waves. Their speed is 4 kms. The surface waves are most destructive as they vibrate much.

Question 5.
How does a Volcano erupt? Explain the types of Volcanoes. (T. B. Qn)
Answer:
A volcano is an opening in the crust of the Earth through which heated materials consisting of gases, hot water, lava and fragments of rocks are ejected from the interior of the Earth. A passage in 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’. A large basin shaped crater bounded by steep sides is known as ‘Caldera’.
Types of Volcano: On the basis of periodicity or frequency of eruption, volcanoes are classified into three types.

a. Active Volcanoes: Volcanoes which constantly eject solid, liquid and gaseous materials are known as active volcanoes, e.g. Mt. Etna in Sicily and Stromboli of Italy, Mauna Loa.

b. Dormant Volcanoes: Volcanoes which become quiet after eruption shows no indications of further future eruptions, but erupt again after a long period very violently is called Dormant Volcanoes. These volcanoes cause enormous damage to human life and property.

c. Extinct volcanoes are volcanoes which have not been active for considerable period of time .There are no possibilities of future eruption in these volcanoes. These volcanoes are also called Sleeping or Dead volcanoes. Narcondum, Vesuvius and Krakatoa are examples of extinct volcanoes.

Question 6.
Explain the distribution of volcanoes:
Answer:
The volcanoes of the world are found certain areas. They are closely related to regions of folding and faulting and are found near the sea coast and islands. Most of the volcanoes are found in three belts:

i. Circum pacific belt
ii. Mid continental belt
iii. Mid Atlantic belt.

i. Circum pacific belt: The greatest concentration of volcanoes is found in this belt. It accounts for about two thirds of the world’s volcanoes. So it is also known as “Pacific ring of fire”. This belt starts form New Zealand, continues northwards into New Guinea, Indonesia, Philippines, coastal china, Japan, Kamchatka and Aleutian islands.

ii. Mid continental belt: This belt consist of Italy, Spain, France, Greece, turkey, Iran, Baluchistan, Myanmar and finally ends inn the eastern part of India.

iii. Mid Atlantic Belt: It includes the western part of India and islands east Atlantic Ocean. It extends form ice land t St. Helena including Madeira, Ascension Island, Cape Verde islands, Canary Island, St. Vincent and Azores. Besides a few volcanoes are also found in the Indian ocean-Mauritius Madagascar and in the rift valley region of Africa, consisting ofKilimanjaro.

Question 7.
Explain the materials of the volcanoes.
Answer:
Three types of volcanic materials are distinguished as Liquid, sold and gaseous materials.

1. The liquid material: Lava is the most important liquid material ejected by volcanoes.
The molten rock material is called “Magma” below other earth’s surface, while it is called lava when it reaches the earth’s surface. There’are two main types of lava-acid lava and basic lava.

2. Solid materials: It consists of volcanic dust, volcanic ash, cinder, volcanic bombs and large angular fragments. The finest particles thrown out by volcanoes are called ‘volcanic dust’. They are grey in color and very light in weight. The molten lava shoots up to the sky at the time of explosion.

Then it cools and solidifies into round mass before falling to the earth. It is called “volcanic bomb’. Small lava fragments are thrown out by a volcano during eruption and are known as “lapilli or pumice’. These are angular in shape and as big as finger joints. The smaller fragments of lava smaller than lapilli are like peas and are called “volcanic ash” or ‘Cinder’. The solid angular fragments which are bigger than lapilil are known as ‘Breccia’.

3. Gaseous Material: A variety of gaseous mixture comes out of a volcano, accompanied by liquid and solid materials, e.g. Vapour, hydrogen, carbon dioxide, sulphur, ammonium chloride etc. But vapour or steam is the most important. Sometimes huge amount of steam is thrown out to form dark clouds above the crater, like a ‘cauliflower’ in shape, it may bring heavy downpour of rain.

Question 8.
Explain the causes and effects of volcanoes.
Answer:
In ancient times, Greeks believed that volcanic eruptions were due to anger of Goddess ‘Vulcan’, living under the Mt.Vulcan (Lipari Islands near Sicili of Italy). People thought that volcano was the mountain of fire.
Causes of Volcano: The volcanic eruptions are closely associated with various causes.

• Gases and water vapour formed due to heating of underground water.
• Movement and breaking of major and minor plates of the Earth.
• Ascent of magma forced by excess pressure.
• The temperature inside the Earth increases with the increasing depth 1°C per 32m).
• Formation of magma because of increase in temperature and reduction in pressure.

Effects of volcanoes:

• Volcanoes are natural hazard and disaster which cause extensive damage to life and property.
• Volcanoes cause damage to agricultural fields, industries, dwellings, buildings, roads, railways, airports, dams, reservoirs etc.
• Volcanoes cause diversion of river course and flooding of water.
• Volcanic dust, ash and smoke cause air pollution.
• Volcanic eruption sometimes produce seismic waves.

Question 9.
What is a rock? Describe the different types of rocks. (T. B. Qn)
Answer:
Rock refers to the hard and resistant materials of the earth’s crust. But scientifically rock includes even soft and loose materials like chalk, clay, etc. So, rock refers to any solid materials, hard or soft of which the crust of the earth is formed. All rocks do not have the same chemical composition. But minerals have their own chemical compost in and physical prosperities. .The earth’s crust is made up of various types of rocks

Types of Rocks: Rocks can be classified into three major groups on the basis of their origin or mode of formation. They are:

A. Igneous rocks: The term Igneous is derived from the Latin word “Ignis”, means lire. Thus the igneous rocks are formed by the cooling and solidification of molten material which is called magma. Igneous rocks are also called primary rocks, because they were the firs to be formed. As they are the rocks from which all other types of rocks are derived, they are also called parent rocks.
Igneous rocks are commonly classified on the basis of mode of formation into two major types.

i. Intrusive rocks
ii. Extrusive rocks.

I. Intrusive rocks: The magma cannpt escape out to the earth’s surface, it cols slowly inside the earth’s crust and hardens into rock. This type of rock is known as Intrusive Igneous rock. E.g. Granite and dolerite. These rocks can be divided into two type’s a. Plutonic rocks and b. Hybabyssal rocks.

a. Plutonic rocks: The rocks which are formed due to cooling of magma at great depth inside the earth are called Plutonic igneous rocks.
b. Hybabyssal rocks: These are intermediate rocks between the extruded volcanic rocks and the deep plutonic rocks. They are formed due to cooling and solidification of magma in cracks, pores, crevices etc.

II. Extrusive rocks: Rocks formed by cooling and solidification of lava on the surface of the Earth is called extrusive igneous rocks. E.g. Basalt.

B. Sedimentary Rocks: These rocks which are formed due to aggregation and compactness
of sediments are known as sedimentary. In other words, sedimentary rocks are formed bye day the deposition of sediments derived form older rocks, planets and animals remains by river, winds, glaciers etc and these sediments are hardened into rocks by pressure. As they are formed by the consolidation of sediments. They are called sedimentary rocks. They are also called stratified rocks,

a. Mechanically-formed rocks: The rock which have been formed form the accumulation of rock materials, derived form other rocks and have been cemented together are known as “ Mechanically formed rocks.” The mechanically formed rocks consist of sediments which have been carried and deposited by rivers, glaciers, winds or waves and cemented together with clay or line. On the basis of rock materials. These rocks can be divided into three main categories. They are: Rudaceous rocks, Arernaceous rocks and Argilious rocks.

b. Chemically formed rocks: The chemical often settle down and hardened to form rocks known as chemically formed rocks. For example: Gypsum and rock salt, running water dissolves and carries chemicals and where evaporation takes place, these chemicals are deposited at the mouth of springs, caves or caverns or in lakes. Rock salt and gypsum are formed form deposit of salt in strata on the beds of lakes.

c. Organically formed rocks: Organic rocks are formed form the remains of organisms, i.e. of animals and plants. Examples: coal, limestone etc. On the basis of lime and carbon content, organically formed rocks can be divided into two kinds, namely.

(i) Calcareous rocks: Calcareous rocks are formed mostly from the remains of living organisms. These rocks contain calcium carbonate or lime. They include limestoneand chalk. They are porous and soluble.

(ii) Carbonaceous rocks: These are formed due to the transformation of vegetative matter. Under the impact of heat and pressure the remains of plants are turned into hard layers. E.g. coal.

C. Metamorphic rocks: Rock which has been changes either in form or in composition without disintegration is called metamorphic rocks. These rocks are metamorphosed from igneous sedimentary rocks. Igneous and sedimentary rocks may undergo chemical and physical changes because of pressure and heat and form metamorphic rocks. The intense heat and pressure in the earth’s curst alters the composition and appearance of rocks completely or partially to produce a new type of rocks. In this manner metamorphic. rocks are formed. Marble, Diamond, Quartzite, Ruby, Emerald are the examples of metamorphic rock.

Question 10.
Explain the uses of rocks.
Answer:

• Rocks are one of the most valuable resources to mankind.
• The sedimentary rocks are the chief sources of petroleum and coal
• The metallic minerals are associated with the igneous rocks. The minerals of great economic value are iron ore, nickel, copper, lead, zinc, chromate, manganese, and rare materials like gold, silver and platinum.
• Under tropical conditions the sedimentary rocks also contain reserves of Bauxite, tin and manganese.
• Even metamorphic rocks like marble and precious minerals like gems, rubies, Graphite are most valuable.
• Rocks are also essentially required as a raw material for construction works.
• Further decaying of rocks forms soils.
• The chemical composition as well as physical properties of soil is directly related to the parental rocks. The fertility of the soils is much determined by the rocks. As such rocks also influence agricultural activities of man.

Question 11.
Explain the types of sedimentary rocks?
Answer:
The rocks which are formed due to aggregation and compactness of sediments are known as “sedimentary rocks.” According to their origin and composition, sedimentary rocks can be divided into two main categories. They are:

1. Inorganic rocks: Inorganic rocks are rocks formed from mineral matter which has been obtained by disintegration or decomposition of rocks. Inorganic rocks can be divided into two types. They are

a. Mechanically-formed rocks: The rock which have been formed form the accumulation of rock materials, derived form other rocks and have been cemented together are known as “ Mechanically formed rocks.” The mechanically formed rocks consist of sediments which have been carried and deposited by rivers, glaciers, winds or waves and cemented – together with clay or line. On the basis of rock materials, these rocks can be divided into three main categories. They are:

1. Rudaceous rocks
2. Arernaceous rocks
3. Argilious rocks

i. Rudaceous rocks: Rudaceous rocks are formed due to cementation and consolidation of pebbles and boulders. Rudaceous rocks consist of rock pieces and grave, cemented together, by clay or line. They are porous and can hold water. If the rock pieces are angular in shape and cemented together, they are called breccias. If the rock pieces are rounded and cemented tighter, they are called conglomerate.

ii. Arenaceous rocks: These are formed mainly due to deposition, CQmmentating and consolidation of sane grains e.g. Sand stone.

iii. argillaceous rocks: These rocks are formed largely by fine clay particles e..g. Shale or mudstone these are impermeable.

B. Chemically formed rocks: The chemical often settle down and hardened to form rocks known as chemically formed rocks. For example: Gypsum and rock salt, running water dissolves and carries chemicals and where evaporation takes place, these chemicals are deposited at the mouth of springs, caves or caverns or in lakes. Rock salt and gypsum are formed form deposit of salt in strata on the beds of lakes.

C. Organic Rocks: Organic rocks are formed form the remains of organisms, i.e. of animals and plants. Examples: coal, limestone etc. On the basis of lime and carbon content, organically formed rocks can be divided into two kinds, namely.

a. Calcareous rocks: Calcareous rocks are formed mostly from the remains of living organisms. These rocks contain calcium carbonate or lime. They include limestone and chalk. They are porous and soluble.

b. Carbonaceous rocks: These are formed due to the transformation of Vegetative . matter. Under the impact of heat and pressure the remains of plants are turned into hard layers. E.g. coal.

Question 12.
What is a mineral? Explain the types of minerals. (T. B. Qn)
Answer:
Mineral is a natural inorganic substance which has certain chemical and physical properties. The scientific study of minerals is called Mineralogy. Minerals are used by man for various human activities. Understanding them minerals their types and uses is very important as natural resources of the earth.

Types: Minerals are classified into different types on the basis of nature, texture, and sues. Important among them are,

1. Metallic Minerals: These minerals are not in metallic form and they do not contain metal. A few non-metallic minerals are Mica, Asbestos, Sulphur, lead, Zinc, Phosphate etc.
2. Non-Metallic Minerals: These minerals are not in metallic form and they do not contain metal. A few non-metallic minerals are Mica, Asbestos, Sulphur, Lead, Zinc, Phosphate etc.

Minerals are also classified into other types.
Ferrous minerals which contain Iron e.g. Iron Ore. Non-ferrous minerals – these minerals do not contain ferrous e.g. Bauxite, Mica. – A few minerals are used for making decorative, commercial and precious ornaments are called Precious minerals. E.g. Platinum, Diamond, Gold and Silver. Some minerals are use for the generation of energy. They are Nuclear or atomic minerals e.g. Uranium, Thorium etc.

1st PUC Geography Interior of the Earth Ten Marks Questions And Answers

Question 1.
Explain the landforms created by volcanoes?
Answer:
Various types of landforms are produced by the volcanoes. They can be grouped into

1. Extrusive landforms
2. Intrusive landforms

1. Extrusive landforms: The landforms which have been formed due to the accumulation and solidification of lava and other materials given out by volcanoes are known as extrusive landforms. The important extrusive land forms are:

a. Volcanic cones: volcanic cones are the most typical form of extrusive features or landforms.

The lava and other ejected materials that reach the surface of the earth are accumulated around the crater, and cones are formed. The formation of cones depends jupon the nature of explosion and the materials emitted out of it. There fore, cones are various types. They are:

• Cinder cones: A volcanic cone formed by volcanic cinder accumulated around the crates is called cinder cone.
• Ash cone: A cone shaped hill formed by of volcanic ash that is built up around a volcanic ent is called ash cone.
• Composite cone: A volcanic cone composed of alternative layers of ash, cinder and lava is called composite cone.
• Parasite cone: Some times, many smaller cones are developed in the neighborhood of the main cone. They are called parasite cone.

b. Crater: A crater is pit at the top of volcanic vent, during volcanic eruption, materials form the top of the cone are blown off and a bowl- shaped depression is formed. It is known as crater.
Caldera: Sometime a violent explosion blow away the original cone and forms a large basin-shaped depression called caldera
Volcanic spine: The acid lava, which is vicious, solidifies quickly and blocks the vent. This stands up as a steep-sided cone called spine or plug.
Lava dome: The shape of lava dome is determined by the nature of lava. The highly fluid basic lava builds up shield dome with gently rising slopes, and flattened top. The basic lava, which is highly viscous, builds up dome with a great height and steep slope
Lava plateau: An extensive elevated land made up of depositional lava called lava plateau.

2. Intrusive land forms: Intrusive landforms occur when lava solidifies with the earth’s. crust and gives rise to various shapes or forms. Intrusive landforms are formed along the bedding planes of sedimentary rocks. There are various forms of intrusive landforms. They are:

Dyke: The Magma from the interior of the earth finds its way towards the surface through a passage. When it is able to reach the surface, it cools and solidifies, and a vertical or highly inclined feature is formed, and such a features is called dyke.
Sill: A sheet of magma which lies along the bedding plan is called sill.
Laccolith: Laccolith is a large mound of igneous rock formed along a bedding plane in the sedimentary rock layers.
Batholith: Batholith is a very large dome – shaped intrusion of igneous rock. It is exposed to the surface only after considerable erosion.

Hot springs or thermal spring’s are more common. The water sinks deep inside where the rocks are heated. The heated water rises to the surface without any explosion. Such springs contain dissolved minerals which are of medicinal value. They can be also used to generate electricity. Iceland has thousands of hot springs. A Geyser is a hot spring form which a column of hot water and stream are alternatively ejected to a great height.