Important Geographical Concept : Part-2
The most popular argument regarding the origin of the universe is the Big Bang Theory. It is also called expanding universe hypothesis.
Edwin Hubble, in 1920, provided evidence that the universe is expanding. As time passes, galaxies move further and further apart.
The following stages in the development of the universe according to Big Bang Theory:
(i) In the beginning, all matter forming the universe existed in one place in the form of a “tiny ball” (singular atom) with an unimaginably small volume, infinite temperature and infinite density.
(ii) At the Big Bang the “tiny ball” exploded violently. This led to a huge expansion. It is now generally accepted that the event of big bang took place 13.7 billion years before the present. The expansion continues even to the present day. As it grew, some energy was converted into matter. There was particularly rapid expansion within fractions of a second after the bang. Thereafter, the expansion has slowed down. Within first three minutes from the Big Bang event, the first atom began to form.
(iii) Within 300,000 years from the Big Bang, temperature dropped to 4,500K (Kelvin) and gave rise to atomic matter. The universe became transparent.The expansion of universe means increase in space between the galaxies.
- It is a massive, irregularly-shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.
Types of plate boundaries:
There are three types of plate boundaries:
(1) Convergent Plate Boundaries: In this type of plate boundaries two lithospheric plates collide withe each other and give birth to fold mountains.
(2)Divergent boundaries: In this type of boundaries two lithospheric plates move opposite to each other and give birth to new crust by filling up the lava in vacant space and its solidification.
(3)Transform boundaries: In this type of plate boundaries two lithospheric plates move along the fault line without affecting each other. Earthquakes are common phenomena due to the movement of these plates.
- The major plates are as follows :
(i) Antarctica and the surrounding oceanic plate
(ii) North American (with western Atlantic floor separated from the South American plate along the Caribbean islands) plate
(iii) South American (with western Atlantic floor separated from the North American plate along the Caribbean islands) plate
(iv) Pacific plate
(v) India-Australia-New Zealand plate
(vi) Africa with the eastern Atlantic floor plate
(vii) Eurasia and the adjacent oceanic plate
- Some important minor plates are listed below:
(i) Cocos plate : Between Central America and Pacific plate
(ii) Nazca plate : Between South America and Pacific plate
(iii) Arabian plate : Mostly the Saudi Arabian landmass
(iv) Philippine plate : Between the Asiatic and Pacific plate
(v) Caroline plate : Between the Philippine and Indian plate (North of New Guinea)
(vi) Fuji plate : North-east of Australia
More Coming Soon…
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