Structure of the Earth’s Interior. Do you REALLY believe? ? ?. All the planets of the solar system came out of the Sun!! Humans have been able to peep into the mantle!! All the Interior of the Earth is in molten state!! The Earth has only one North Pole!!. How was Earth formed?.
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Big Bang Theory
Solar Nebular Theory
The birth and evolution of the universe
-14 billion years ago,
-huge explosion -the Big Bang.
-the universe was very hot and dense and filled with energy.
-As space expanded, the temperature began to fall and the first particles of matter formed from the energy.
-After more than 1 billion years, the first stars and galaxies had formed. --The Solar System, including our Earth, formed about 4.6 billion years ago.
Due to continuous accretion, the meteorites grew larger in size. Several meteorites got together and the formed the early asteroids.
Verification of this assumption is very difficult. The deepest hole dug into the earth is only 16 km deep. Hence direct methods cannot be used to find out about the interior of the earth.
HOW TO STUDY THE MYSTERIES OF THE INTERIOR OF THE EARTH??
Watch Video: http://www.youtube.com/watch?v=9J6EHnra7Mo&NR=1
Watch Video: http://www.youtube.com/watch?v=7NqmHtIjCJ0&NR=1
Following is a description of the experiment conducted by E Mohorovicic, a Dutch physicist who proved the existence of the crust and the mantle.
ER distance = 160 km
Explosion at-09.00.00 am
1st set of P waves reach R at 09.00.32 am
2nd set of P waves reach R at 09.00.40 am
Speed of waves= 160/32= 5 km/sec
Time taken to reach from EB to BR=
40 seconds * 5 km= 200 km
EB= BR= 100 km
Therefore by ASA, proved.
According to Pythagoras Theorem, EB2=EA2+AB2
= 10000= 6400+AB2
= 3600 kms = 60 km ( Thickness of the crust)
An explosion is created at point E on the earth’s surface due to which S waves travel in all directions. Most of them are refracted by the mantle and are received at points R1, R2, R3 and R4. Some of these S waves are blocked by the core, which suggests that it is in a liquid state. This is why no S waves reach the seismic recording station R5.
The part of the Earth between the points R3 and R4 (including R5) is called the S wave shadow zone and the angle formed between these points at the centre of the earth (angle R3CR4) is always equal to 150º.
Watch Video: http://www.youtube.com/watch?v=v_1QcI3BWRk&feature=related
A point to be noted here is that while S waves are blocked by the core (outer core), P waves are received at R5 and all other stations in the shadow zone. P wave velocities are not uniform throughout the core, which indicates that there is a solid inner core (where the velocity of P waves increases).
1. The thickness of the oceanic crust is in the range of 10 to 20 km. Therefore magma from the mantle can directly erupt through submarine volcanoes. A chemical analysis of this lava gives us the composition of the mantle.
2. The velocity of P waves in the mantle is about 8 km/s. Scientists passes P waves through several rocks present on the earth and found that the velocity of P waves equals to 8 km/s in only three rocks, viz. Peridotite, Dunite and Eclogite. It is interesting to note that these rocks are found mostly in the vicinity of submarine volcanoes.
3. It is believed that the primitive earth formed as a result of several meteoritic impacts. It is possible that the composition of the mantle is similar to the meteorites falling on the earth even today. A chemical analysis of meteorites gives results similar to the two methods discussed above.