BOWELS OF EARTH
1. Context
Scientists have excavated a new secret from the Earth’s inner world. The researchers, in a new study, have confirmed the existence of a fifth new layer.
2.Layers of the earth
Starting at the center, Earth is composed of four distinct layers. They are, from deepest to shallowest, the inner core, the outer core, the mantle and the crust. Except for the crust, no one has ever explored these layers in person
The core is the centre of the earth and is made up of two parts: the liquid outer core and solid inner core. The outer core is made of nickel, iron and molten rock. Temperatures here can reach up to 50,000 C
2.1.Inner Core
This solid metal ball has a radius of 1,220 kilometers (758 miles), or about three-quarters that of the moon
It’s located some 6,400 to 5,180 kilometers (4,000 to 3,220 miles) beneath Earth’s surface
Extremely dense, it’s made mostly of iron and nickel. The inner core spins a bit faster than the rest of the planet
2.2.Outer Core
This part of the core is also made from iron and nickel, just in liquid form. It sits some 5,180 to 2,880 kilometers (3,220 to 1,790 miles) below the surface.
Heated largely by the radioactive decay of the elements uranium and thorium, this liquid churns in huge, turbulent currents. That motion generates electrical currents
2.3.The Crust
This is the outside layer of the earth and is made of solid rock, mostly basalt and granite. There are two types of crust; oceanic and continental. Oceanic crust is denser and thinner and mainly com​posed of basalt. Continental crust is less dense, thicker, and mainly composed of granite
2.4.Mantle
The mantle lies below the crust and is up to 2900 km thick. It consists of hot, dense, iron and magnesium-rich solid rock. The crust and the upper part of the mantle make up the lithosphere, which is broken into plates, both large and small
3.Fifth Layer of the earth
The four known layers of the Earth include the crust, mantle, outer liquid and inner solid core. The fifth layer the innermost inner core lies at the Earth’s centre, within the inner core
The fifth layer is made of iron and nickel, the same materials that comprise the rest of the inner core.
The difference between the two parts of the inner core could stem from how iron atoms are arranged to form a solid
The inner core as a whole was liquid in the early years of the Earth’s existence, turning into a solid as the Earth cooled
Scientists rely on seismic waves — shockwaves generated during an earthquake — to ‘see’ the Earth’s interiors
These waves behave differently as they pass through diverse materials. For example, they travel slower when they pass through hot materials.
This stems from the fact that waves from large earthquakes following a few set paths have been studied repeatedly, leaving the rest of the inner core unexplored.
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Previous Year Questions:
1.Consider the following statements (2018)
1.Barren island is the active volcano located in the Indian territory
2.Barren Island lies about 140km east of Great Nicobar
3.Last time when barren Island volcano errupted was in 1991and it has remained inactive since then
Which of the above given statement is/ are correct
A.1 Only B. 2 Only C.Both 1 and 2 D. Neither 1 Nor 2
Answer (A)
2.In the structure of the Planet earth, below the mantle, the core is mainly made up of which of the following? (2009)
A.Alluminium B.Chromium C.Iron D.Silicon
Answer (C)
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Source:DownToEarth, GelogicalSurvey
