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UPSC GS Geography short notesInterior of The Earth T he configuration of the surface of earth is largely a product of the process operating in the interior of the earth. Exogenic as village endogenic process are constantly shaping the landscape. Therefore, it is essential to get acquainted with the forces that influence landscape development.Earthquake Earthquake is a natural event and it is caused due to release of energy which generate waves that travel in all direction.The release of energy occurs along a fault. A ball is a start break in the crystal rocks. Rocks along a cold tend to move in opposite direction. All the underlying rocks starta to press them, the friction locks them together. However, the tendency to move apart at some point of time overcomes the friction. As a result, the blocks get deformed and eventually, they slide past one another abruptly.This poses a release of energy, and energy waves travel in all directions. The point where the energy is released is the focus of an earthquake, alternatively, it is called hypocentre. The energy waves travelling in different directions reach the surface. The point on the surface, nearest to the focus, is called epicentre. It is the 1st to experience the waves. It is a point directly above the focus.Earthquake wavesAll natural earthquakes take place in the lithosphere which is about 200 km depth from the surface of the earth. An instrument called ‘seismograph’ record the waves reaching the surface. Earthquake waves are basically of two types, first, body waves and seconds, surface waves. Body waves are generated due to the release of energy at the focus and move in all the directions travelling through the body of the earth. That is why they are called body waves. The body wave interacts with the surface rocks and generate a new set of waves called surface waves. These waves move along the surface. The velocity of waves changes as they travel through materials with different densities. The denser material, higher is the velocity. Their direction also changes as they reflect or refract when coming across material with different densities.There are two types of body waves, P-waves or primary waves, moves faster and are the first to arrive at surface. They travel through gaseous, liquid and solid materials while S-waves or secondary waves travels through solid material which make it essential to know about the interior of the earth. The surface waves are the last to report on the seismograph. These waves are more destructive. They caused displacement of rocks, and hence, the collapse of structures occurs.Types of earthquakei. The most common ones car tectonic earthquake. They are generated due to sliding of rocks along a fault plane. ii. Special class of tectonic earthquake is sometimes recognised as volcanic earthquake. However, these are confined to areas of active volcanoes.iii. In the areas of intense manic activity, sometime the roofs of underground mines collapse causing minor tremors. These are called collapse earthquake.iv. Ground shaking may also occur due to explosion of chemicals or nuclear devices. Such tremors are called explosion earthquake.v. The earthquakes that occur in the areas of large reservoirs are referred to as reservoir induced earthquake.Structure of The Earth The crestIt is the outermost solid part of the earth. It is brittle in nature. The thickness of the crust where is under the oceanic and continental areas. Oceanic crust is thinner as compare to Continental crust. The main thickness of oceanic crust is 5 km where is that of the continental is around 30 km. The Continental crust is thicker in the areas of major mountain system. It is as much as 70 km thick in the himalayan region.The Mantle The portion of interior beyond the crust is called mantle. The mantle extends from most discontinuity to a depth of 2900 km. The upper portion of the mantle is called asthenosphere. The word astheno means weak. It is considered to be extending up to 400 km. It is the main source of magma that finds its way to the surface during volcanic eruption. It has a density higher than the crust. The crust and the uppermost part of the mental or cold lithosphere. Its thickness ranges from 10 kilometre to 200 km. The lower mantle extends beyond the asthenosphere. It is in solid state.The coreThe core mental body is located at the depth of 2900 km. The outer core is in liquid state while the inner core is in solid-state. The density of material at the mental core boundary is around 5 g per centimetre and at the centre of the earth is at 6300 km, the density value is around 13 g per centimetre. The core is made up of very heavy material mostly constituted by nickel and iron. It is sometimes referred to as the nife layer.Volcanos and volcanic landformsVolcanoes are classified on the basis of nature of eruption and the forms developed at the surface. Major types of volcanoes are as follows:Shield Volcano * Largest of all the volcanoes* Made up of basalt, a type of flower that is very fluid when erupted.* Explosive when gets in contact with water.* Example is The Hawaiian Volcano Composite Volcano * cooler and more vicious lawas than besalt * Result in explosive eruption* Along with lava, large quantities of pyroclastic material and assess find their way to the ground* This material accumulate in the vicinity of the vent openings leading to formation of layers, and this makes the mouth appear as composite volcanoes Caldera* these are the most explosive of the earths volcanoes * They are usually so explosive that when the erupt they tend to collapse on themselves rather than building any tall structure.* Dear explosive Ness indicates that the magma chamber supplying the Labe is not only huge but also in close vicinity Flood besalt provinces * highly fluid lava that flows for long distance* The Lava attain thickness of more than 50 meter* The Deccan Traps and Maharashtra Plateau are one such example Mid ocean ridge volcano* occurs in oceanic areas* There is a system of mid ocean ridge more than 70,000 km long that stretches through all the ocean basin Volcanic landformsIntrusive forms* lava develops into Igneous rocks* Cooling takes place when lawa reaches the surface and also while lava is still in the crustal portion * Depending on the location of cooling of lava, Ignatius rocks are classified as volcanic rocks and plutonic rocks.* Lava that cools within the crustal ocean are called intrusive formsBatholith * magnetic material that cools on the crust develop into domes* They appear on the surface only after the denudational process removes the overlaying materials* Batholiths are cooled portion of magma ChambersLaccoliths * Large dome shaped intrusive bodies with level base and connected by pipe like conduit from below* Localised source of lava that finds its way to the surface* Karnataka Plateau is one such exampleLapolith, Phacolith and Sills* as and when lava move upwards, a portion of the same it tends to move in a horizontal direction whenever it finds a weak plane.* In case it forms a set of saucer shape, concave to the sky body, it is called Lapolith * The wavy material have a definite conduit to source beneath in the form of magma chamber called phacoliths.* The near her gentle bodies of the intrusive igneous rocks are called sills or sheetDykes* when the lava makes its way through the cracks and the fissures develop in the land, its solidifies almost perpendicular to the ground.* It gets cooled in the same position to develop a wall like structure called dykes. * The Maharashtra area and Deccan traps are one such examples.
UPSC GS Geography short notes
Interior of The Earth
T
he configuration of the surface of earth is largely a product of the process operating in the interior of the earth. Exogenic as village endogenic process are constantly shaping the landscape. Therefore, it is essential to get acquainted with the forces that influence landscape development.
Earthquake
Earthquake is a natural event and it is caused due to release of energy which generate waves that travel in all direction.
The release of energy occurs along a fault. A ball is a start break in the crystal rocks. Rocks along a cold tend to move in opposite direction. All the underlying rocks starta to press them, the friction locks them together. However, the tendency to move apart at some point of time overcomes the friction. As a result, the blocks get deformed and eventually, they slide past one another abruptly.This poses a release of energy, and energy waves travel in all directions. The point where the energy is released is the focus of an earthquake, alternatively, it is called hypocentre. The energy waves travelling in different directions reach the surface. The point on the surface, nearest to the focus, is called epicentre. It is the 1st to experience the waves. It is a point directly above the focus.
Earthquake waves
All natural earthquakes take place in the lithosphere which is about 200 km depth from the surface of the earth. An instrument called ‘seismograph’ record the waves reaching the surface. Earthquake waves are basically of two types, first, body waves and seconds, surface waves. Body waves are generated due to the release of energy at the focus and move in all the directions travelling through the body of the earth. That is why they are called body waves. The body wave interacts with the surface rocks and generate a new set of waves called surface waves. These waves move along the surface. The velocity of waves changes as they travel through materials with different densities. The denser material, higher is the velocity. Their direction also changes as they reflect or refract when coming across material with different densities.
There are two types of body waves, P-waves or primary waves, moves faster and are the first to arrive at surface. They travel through gaseous, liquid and solid materials while S-waves or secondary waves travels through solid material which make it essential to know about the interior of the earth. The surface waves are the last to report on the seismograph. These waves are more destructive. They caused displacement of rocks, and hence, the collapse of structures occurs.
Types of earthquake
i. The most common ones car tectonic earthquake. They are generated due to sliding of rocks along a fault plane.
ii. Special class of tectonic earthquake is sometimes recognised as volcanic earthquake. However, these are confined to areas of active volcanoes.
iii. In the areas of intense manic activity, sometime the roofs of underground mines collapse causing minor tremors. These are called collapse earthquake.
iv. Ground shaking may also occur due to explosion of chemicals or nuclear devices. Such tremors are called explosion earthquake.
v. The earthquakes that occur in the areas of large reservoirs are referred to as reservoir induced earthquake.
Structure of The Earth
The crest
It is the outermost solid part of the earth. It is brittle in nature. The thickness of the crust where is under the oceanic and continental areas. Oceanic crust is thinner as compare to Continental crust. The main thickness of oceanic crust is 5 km where is that of the continental is around 30 km. The Continental crust is thicker in the areas of major mountain system. It is as much as 70 km thick in the himalayan region.
The Mantle
The portion of interior beyond the crust is called mantle. The mantle extends from most discontinuity to a depth of 2900 km. The upper portion of the mantle is called asthenosphere. The word astheno means weak. It is considered to be extending up to 400 km. It is the main source of magma that finds its way to the surface during volcanic eruption. It has a density higher than the crust. The crust and the uppermost part of the mental or cold lithosphere. Its thickness ranges from 10 kilometre to 200 km. The lower mantle extends beyond the asthenosphere. It is in solid state.
The core
The core mental body is located at the depth of 2900 km. The outer core is in liquid state while the inner core is in solid-state. The density of material at the mental core boundary is around 5 g per centimetre and at the centre of the earth is at 6300 km, the density value is around 13 g per centimetre. The core is made up of very heavy material mostly constituted by nickel and iron. It is sometimes referred to as the nife layer.
Volcanos and volcanic landforms
Volcanoes are classified on the basis of nature of eruption and the forms developed at the surface. Major types of volcanoes are as follows:
Shield Volcano
* Largest of all the volcanoes
* Made up of basalt, a type of flower that is very fluid when erupted.
* Explosive when gets in contact with water.
* Example is The Hawaiian Volcano
Composite Volcano
* cooler and more vicious lawas than besalt
* Result in explosive eruption
* Along with lava, large quantities of pyroclastic material and assess find their way to the ground
* This material accumulate in the vicinity of the vent openings leading to formation of layers, and this makes the mouth appear as composite volcanoes
Caldera
* these are the most explosive of the earths volcanoes
* They are usually so explosive that when the erupt they tend to collapse on themselves rather than building any tall structure.
* Dear explosive Ness indicates that the magma chamber supplying the Labe is not only huge but also in close vicinity
Flood besalt provinces
* highly fluid lava that flows for long distance
* The Lava attain thickness of more than 50 meter
* The Deccan Traps and Maharashtra Plateau are one such example
Mid ocean ridge volcano
* occurs in oceanic areas
* There is a system of mid ocean ridge more than 70,000 km long that stretches through all the ocean basin
Volcanic landforms
Intrusive forms
* lava develops into Igneous rocks
* Cooling takes place when lawa reaches the surface and also while lava is still in the crustal portion
* Depending on the location of cooling of lava, Ignatius rocks are classified as volcanic rocks and plutonic rocks.
* Lava that cools within the crustal ocean are called intrusive forms
Batholith
* magnetic material that cools on the crust develop into domes
* They appear on the surface only after the denudational process removes the overlaying materials
* Batholiths are cooled portion of magma Chambers
Laccoliths
* Large dome shaped intrusive bodies with level base and connected by pipe like conduit from below
* Localised source of lava that finds its way to the surface
* Karnataka Plateau is one such example
Lapolith, Phacolith and Sills
* as and when lava move upwards, a portion of the same it tends to move in a horizontal direction whenever it finds a weak plane.
* In case it forms a set of saucer shape, concave to the sky body, it is called Lapolith
* The wavy material have a definite conduit to source beneath in the form of magma chamber called phacoliths.
* The near her gentle bodies of the intrusive igneous rocks are called sills or sheet
Dykes
* when the lava makes its way through the cracks and the fissures develop in the land, its solidifies almost perpendicular to the ground.
* It gets cooled in the same position to develop a wall like structure called dykes.
* The Maharashtra area and Deccan traps are one such examples.