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The surface of the earth is made up of soil and rock. Most of the part of the earth is made of rock> Rock are also found below the sea as well as in interior part of the earth.
Oxygen O 46.6
Silicon Si 27.7
Aluminium Al 8.1
Iron Fe 5
Calcium Ca 3.6
Sodium Na 2.8
Potassium K 2.6
Magnesium Mg 2.1
other - 1.5
The outer surface of the earth is uneven as there is the presence of high mountains, plateaus and plains. The uneven outer surface is known as topography. The earth surface is always changing. It is believed that nearly 30 million years ago, Nepal and Himalayas were in the womb of Tethys Ocean stretching from the northern part of India to the southern part of Tibet.
The change is sometimes sudden and sometimes over a period. There are two kinds of agents that cause change. They are :
Shale – sedimentary rocks
Marble – Metamorphic rocks
Pumice – Volcanic (Igneous)
Basalt – Volcanic (Igneous)
Slate – Metamorphic rocks
Conglomerate – sedimentary rocks
Obsidian – Volcanic (Igneous)
Schist – Metamorphic rocks
Limestone – sedimentary rocks
Igneous and metamorphic rocks never have fossil on them because they are formed at high temperature where there are no fossils.
Plutonic rocks have big crystals because it is formed by cooling of magma inside rock.
Pumice floats on water because they are porous in nature.
Silica is a mineral whereas sandstone is a rock because silica is pure substance and sandstone is formed from the minerals.
Minerals are natural solid, crystalline and pure substances found in the crust of the earth.
Minerals differ with each other in colour, luster, hardness and cleavage.
Rocks are advantageous to us because they are used to build monuments. Hydroelectric dams are built by using rocks. Rocks are used as gravel for the construction. Rocks are used as minerals. Hence, they are used as main source of energy.
When the sediment remains for thousands of years at pressure it gets cemented together. In this way sedimentary rocks are formed.
When magma trying to come out at the surface of the earth gets cooled inside the earth, it forms plutonic rocks.
The main components of rocks are sails, pebbles, sand and different types of minerals.
The uses of rocks are:
The hard and solid part of the earth crust is known as rock Its types are: i) Igneous rock
ii) Sedimentary rock
iii) Metamorphic rock
The rocks which are formed by the cooling of magma when it comes on the earth surface is called igneous rock. They are formed when the hot magma from the interior part of the earth comes out on the earth crust and solidify to a type of rock known as igneous rocks. They are very hard and crystalline
The rocks which are formed by the sedimentation of remains of plants and animals for thousands of years are known as sedimentary rocks. They are formed by the deposition of remains of plants and animals for thousands of year. Under high temperature and pressure, they get cemented together and convert into sedimentary rocks. Such rocks are rich in fossils and soft in nature.
The rocks which are formed from the sedimentary rocks and igneous rocks under heat and pressure are known as metamorphic rock. Metamorphic rock is formed due to the certain modification in sedimentary rocks and igneous rocks due to the effect of heat and pressure. For example: limestone converts into marble, shale into slate, etc.
|Igneous rocks||Sedimentary rocks|
|They are formed when the hot magma from the interior part of the earth comes out on the earth crust and solidifies.||They are formed by the deposition of remains of plants and animals for thousands of year|
|They do not contain any fossils||They contain fossils|
|Eg: Basalt, obsidian, pumice, etc.||Eg: shale, limestone, etc.|
|Metamorphic rocks||Sedimentary rocks|
|Metamorphic rock is formed due to the certain modification in sedimentary rocks and igneous rocks due to the effect of heat and pressure.||They are formed by the deposition of remains of plants and animals for thousands of year|
|They may or may not contain fossils||They contain fossils|
|Eg: marble, gneiss, etc.||Eg: shale, limestone, etc.|
The layer of earth below the earth crust contain the materials in a hot molten state known as magma.
The hot molten magma after reaching the earth's surface is known as lava.
|The hot molten liquid present in the interior part of the earth is called magma.||The same magma after coming out on the earth's surface is known as lava|
|Magma when comes out on the earth forms lava||Lava, after cooling and solidifying, forms rocks.|
The hard and solid part of the earth's surface is known as the rock. Rocks may be composed of one or more minerals. Rock may be in the form of the smaller rocks as well in the form of boulders. Not only in the form of hard and boulders, rocks are also found in the form of sand and fine clay. The hard rocky surface of the earth is covered with the soil. The differentlayers of rocks are bedrock, subsoil and topsoil.
The materials in the inner part of the earth are in molten state due to high temperature and pressure.
Which is not a type of volcano?