Dear Readers,
Current affairs is an important component of several competitive exams such as the UPSC Civil Services Examination, SSC-CGL, Bank PO, PSU entrance tests, etc. Therefore, understanding the terms/concepts/events that make news is critical for aspirants. We at PaGaLGuY bring you series of articles in explaining some of these important concepts/events. In this article we will read about movement of plates.
Plates move over Asthenosphere. With movement their outer edges interact in the following 3 ways:
1) Divergent/Constructive boundaries:
a) This type of movement can be seen where new crust is generated when the plates pull away from each other, creating a rift.
b) The sites where these plates move away from each other are called spreading sites.
c) Along the plate boundaries, the lava spreads from long fissures. Beneath the rift, lava rises from the mantle. It oozes up into the gap and hardens into solid rock, forming a new crust on the torn edges of the plates.
d) The best example of divergent boundaries is Mid-Atlantic Ridge, where the American site is separated from the Eurasian & African plates.
2) Convergent/Destructive boundaries:
a) This type of movement can be seen where the old crust is destroyed when the plates pull away from each other.
b) The impact of the two colliding plates creates a compressional force, securing the edge of one or both plates up into a rugged mountain range (fold mountain range). Sometimes it also bends the other plate down into a deep seafloor trench (oceanic trench).
c) In this process, the descending plate heats up, melts and gets converted into magma that comes out through volcanoes to form a new continental plate.
d) In this type the heavier plate (oceanic) is subdued in the lighter plate (continental).
f) The location where the plates sink is called a subduction zone.
Here are some ways of convergence :
i) Between an Oceanic & Continental plate
ii) Between two Oceanic plates
iii) Between two continental plates.
g) The west coast of South America is a convergent boundary between the Nazca plate and the South American plate.
3) Transform boundaries:
a) This type of movement can be seen where the crust is neither produced nor destroyed as the plates slide horizontally past each other.
b) This type of movement of plates is parallel to each other in the horizontal direction.
c) Rocks that line the boundary are pulverised as the plates grind along, creating a linear fault valley or undersea canyon.
d) No magma is formed in this type unlike convergent and divergent movements. Thus, crust is cracked and broken at transform margins, not created or destroyed.
e) The best example is the San Andreas fault on the Pacific coast of the United States.
To get fresh updates about different exams on your Facebook & Twitter timelines, subscribe to our pages created specifically for them. We will post only exam specific links on these pages:
Bank PO:
Facebook: https://www.facebook.com/pagalguybankpo
Twitter: https://twitter.com/PaGaLGuYBankPO
SSC – CGL:
Facebook: https://www.pagalguy.com/ssc
Twitter: https://twitter.com/pagalguyssc
UPSC:
Facebook: https://www.facebook.com/pages/Pagalguy-UPSC/951926044840262
Twitter: https://twitter.com/PaGaLGuYUPSC