MANTLE
This layer lies below the crust.
Its thickness is about 2900km and the density of substance in the mantle ranges from 3.0 to 4.7 .
CORE
The earths core lies below the mantle.Its thickness may be about 3471 km.
Its radius is 6371km,according to IUGG.
Its divided into two parts,the outer core and the inner core.the outer core is probably in a liquid state and the inner core in a solid state.
The core mainly consists of iron with some important amount of nickel and sulphur (NIFE).The central part of core of earth is known as NIFE.
After the mantle,the earths density goes on increasing rapidly towards its center and finally is more than 13.
The temperature of the central part of the earth may be about 5000°c.
The study of the earths interior helps us the understand the original rocks in the earths crust and their later transformation.
Newton told the earth to like as narangi.
The earth part of core is also known as Berisphere.
ROCKS
The solid parts of the earth's crust are called rocks.Most of the rocks are made up of two or more minerals.
In the same type of rocks,the proportions of minerals may be different in different areas.
Rocks may not always necessarily be hard.
Minerals are obtained from rocks.
Rocks are classified in three main types depending on the process of their formation:
(a) Igneous rocks
(b) Sedimentary rocks
(c) Metamorphic rocks
IGNEOUS ROCKS
Hot lava pours out at the time of volcanic eruptions and cools down later on,forming rocks.
The molten material known as magma,sometime cool down beneath the earth's crust,again forming rocks.
Both these type of the rocks are known as Igneous rocks.
When the earth's surface first became solid after it cooled down from its hot liquid state,the original rocks of the earths crust were formed.they are the primary Igneous rocks,which are usually not found today.
Igneous rocks are generally harder and granular.
There are no layers in Igneous rocks.
Fossils are not found in Igneous rocks.
The formation of Igneous rocks takes places beneath and above the surface of earth.
Rocks formed by the cooling of molten matter beneath the earths surface are called intrusive igneous rocks.'Granite' and 'Gabbro' are the mainly examples of these rocks.
The intrusive rocks are the crystalline rocks.
Sometimes,the molten matter oozes out through cracks in the earth's crust and spread on the surface,forming extrusive igneous rocks.
Gabbro,Obsidian,Basalts etc. are examples of extrusive rock
A very large area of the Deccan plateau consist of basalt rocks.
These rocks contain silica from 40 to 80%,other are feldspar,magnesium and iron etc.
Other example of Igneous rocks are Granite,pumic stone,basalt and Gabbro.
SEDIMENTARY ROCKS
They are formed by the deposition ,sedimenentation and lethification of sediments over a long period of time.
As layers over layers get deposited,over a period of time,unified sedimentary rocks are formed on account of the tremendous pressure exerted by the layers above.
Sometimes the remains of plants,dead animals etc. are found in deposited material.Such fossil containing sedimentary rocks are useful for studying life on earth.
Sandstone,limestone,shale are some examples of sedimentary rocks.
Limestone is white as well as black.
Sandstone is dull white,pink,bright red or sometime black.
METAMORPHIC ROCKS
The nature of Igneous and sedimentary rocks changes due to the effects of tremendous heat or pressure and new,transformed rocks called metamorphic rocks,are formed.
Minerals in the rocks get restructured on account of heat and pressure.This brings about a change in the original formation of the rocks.
For examples of metamorphic rocks formed from igneous and sedimentary rocks.
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