Internal structure of earth :
The earth is made up of several concentric layers. Concentric means having a common centre. The earth has one layer inside another.
Broadly, there are three layers of the earth:
· It is the outermost layer over the earth’s surface.
· It is the thinnest of all the layers.
· About 35 km on the continental masses and only 5 km on the ocean floors.
· The main minerals constituting the continental mass are:
· The continental mass is also called ‘sial’.
· The name sial is derived from letters ‘si’ of silicon and ‘al’ of alumina.
· The main mineral constituents of the oceanic crust are:
· The oceanic crust is called ‘sima’.
· The root of the word sima is ‘si’ from silica and ‘ma’ from magnesium.
· It is the layer just beneath the crust and extends up to a depth of 2900 km below the crust.
· As Earth began to take shape about 4.5 billion years ago, iron and nickel quickly separated from other rocks and minerals to form the core of the new planet.
· The molten material that surrounded the core was the early mantle.
· Over millions of years, the mantle cooled. Water trapped inside minerals erupted with lava, a process called “outgassing.”
· As more water was outgassed, the mantle solidified.
· The transfer of heat and material in the mantle helps determine the landscape of Earth.
· Activity in the mantle drives plate tectonics, contributing to volcanoes, seafloor spreading, earthquakes, and orogeny (mountain-building).
· The asthenosphere is the denser, weaker layer beneath the lithospheric mantle.
· It is the innermost layer .
· The core consists of outer core and inner core.
· It is mainly made up of:
· The innermost layer is also called ‘nife’.
· The name nife is derived from the word ‘ni’ from nickel and ‘fe’ from ferrous meaning iron.
· The temperature and pressure of the central core is very high.
Outer Core :
· mostly composed of liquid iron and nickel.
Inner Core :
· The temperature of the inner core is far above the melting point of iron.
· However, unlike the outer core, the inner core is not liquid or even molten.
· The inner core’s intense pressure—the entire rest of the planet and its atmosphere—prevents the iron from melting