Due to the nature and changing forms of rocks, the construction and development of various landforms, changes in their shape and form over time, variations have been seen in them from place to place. This statement shows the importance of rocks in geographical studies. The outer circle of the earth is known as the crust, crust or crust, which is the solid state
Is in In simple terms, hard and resistant materials of crust are called rocks, but in geography and geology the term 'rock' is used in a wider sense. Under this, all the hard or soft materials of the crust are included. Therefore, not only hard matter under the rock
Such as granite, sandstone and marble, but also soft and loose materials like chalk, mud, sand, salt and coal etc. are also included.
Major Constituents of Earth's Crust
About 98 percent of the entire earth's crust is composed of eight elements oxygen (O), silicon (SI), aluminum (AI), iron (Fe), calcium (Ca) sodium (Na), potassium (K) and magnesium (Mg). (Fig: 1) and the rest is made up of titaniera (TI), hydrogen (H), phosphorus (P), manganese (Mn), sulfur (S), carbon (C), nickel (Ni) and other substances. . By weight, about 75 percent of the crust is made up of oxygen and silicon. These elements are very important.
Minerals
A mineral is a natural, organic or inorganic element, which has a graded molecular structure, definite chemical composition and specific physical properties. Minerals are made up of two or more elements but, sometimes, monogamous minerals such as sulfur, copper, silver, gold, graphite are also found.
Types of minerals
Minerals are generally classified into metallic and non-metallic types.
The surface of metallic minerals is generally smooth and shiny. Gold, copper, lead etc. are metallic minerals.
The surface of non-metallic minerals is blurred. They cannot reflect the sun's rays. Gypsum, quartz and mica are non-metallic minerals. They do not contain metal fragments.
About 99 percent of the material found in the crust is made up of rock and minerals. Useful minerals are found in some rocks, which provide us with metals and chemicals. The crust rocks are believed to be composed of about 2000 minerals, but contain only six minerals - felspar, quartz, pyroxene, amphiboles, mica and olivine. It is the major mineral that forms rocks.
Different types of rocks
The rock is formed by one or more minerals and there is no definite chemical composition of the mineral components. The rocks are divided into the following three groups based on their construction method:
1. Sedimentary Rocks
2. Igneous rocks
3. Metamorphic Rocks
1. Igneous Rocks
The word 'Igneous' is derived from the Latin word 'ignis' (iginis) which literally means fire. The formation of these rocks is associated with volcanic eruptions. The igneous rock is formed by the cooling of hot and liquid magma under the crust. These rocks are formed due to the freezing of hot and liquid materials. In these rocks there are also crystals, which is why they are also called crystalline rocks. Igneous rocks are considered to be the oldest rocks of Bhuprishta, but they are also being constructed at present. These rocks are always formed on the crust by volcanic action. Due to weathering and transformation of these rocks, other rocks are directly or indirectly formed.Therefore elementary rocks primary rocks is also called. About 90% of the crust is made up of igneous rocks. Major examples of Igneous rocks are granite, cyanite, monozite, dolerite, rhyolite, gabbro, vamalt pogfiri., Obsidian, etc. These rocks are layerless, non-porous and dense. Thus due to the hardness of these rocks, their erosion was very slow.
Classification of Igneous rocks
Igneous rocks can be classified based on the process of origin, the size of the particles, chemical composition.
On the basis of origin, igneous rocks can be classified into two parts:
1.Intrusive igneous rocks: when magma moves upward during volcanic buoyancy if it does not reach the top of the ground and becomes cold within the surface and takes a solid form, then the underlying igneous rock is formed. The rate of cooling of magma in the Earth is low, so the mineral particles are large enough. Granite and dolerite are prominent examples of these rocks.
Types of minerals
Minerals are generally classified into metallic and non-metallic types.
The surface of metallic minerals is generally smooth and shiny. Gold, copper, lead etc. are metallic minerals.
The surface of non-metallic minerals is blurred. They cannot reflect the sun's rays. Gypsum, quartz and mica are non-metallic minerals. They do not contain metal fragments.
About 99 percent of the material found in the crust is made up of rock and minerals. Useful minerals are found in some rocks, which provide us with metals and chemicals. The crust rocks are believed to be composed of about 2000 minerals, but contain only six minerals - felspar, quartz, pyroxene, amphiboles, mica and olivine. It is the major mineral that forms rocks.
Different types of rocks
The rock is formed by one or more minerals and there is no definite chemical composition of the mineral components. The rocks are divided into the following three groups based on their construction method:
1. Sedimentary Rocks
2. Igneous rocks
3. Metamorphic Rocks
1. Igneous Rocks
The word 'Igneous' is derived from the Latin word 'ignis' (iginis) which literally means fire. The formation of these rocks is associated with volcanic eruptions. The igneous rock is formed by the cooling of hot and liquid magma under the crust. These rocks are formed due to the freezing of hot and liquid materials. In these rocks there are also crystals, which is why they are also called crystalline rocks. Igneous rocks are considered to be the oldest rocks of Bhuprishta, but they are also being constructed at present. These rocks are always formed on the crust by volcanic action. Due to weathering and transformation of these rocks, other rocks are directly or indirectly formed.Therefore elementary rocks primary rocks is also called. About 90% of the crust is made up of igneous rocks. Major examples of Igneous rocks are granite, cyanite, monozite, dolerite, rhyolite, gabbro, vamalt pogfiri., Obsidian, etc. These rocks are layerless, non-porous and dense. Thus due to the hardness of these rocks, their erosion was very slow.
Classification of Igneous rocks
Igneous rocks can be classified based on the process of origin, the size of the particles, chemical composition.
On the basis of origin, igneous rocks can be classified into two parts:
1.Intrusive igneous rocks: when magma moves upward during volcanic buoyancy if it does not reach the top of the ground and becomes cold within the surface and takes a solid form, then the underlying igneous rock is formed. The rate of cooling of magma in the Earth is low, so the mineral particles are large enough. Granite and dolerite are prominent examples of these rocks.
(A) Plutonic Igneous Rock - They are formed at very deep depths in geology, where the crystals are found more due to gradual cooling of magma due to higher temperature. The prime example of this is granite.
(B) Hypabyssal - Igneous rocks This type of rocks is formed by solidification of cracks, holes and ducts in the path of lava at the time of volcanic eruption. They are formed below the surface of the earth but sometimes they appear above due to erosion. These rocks are found below the surface in the following forms
(i) Batholith - Lava deposits form in a very steep, sloping domed form below the ground, especially in mountain areas where volcanoes are active. Due to erosion their upper surface becomes visible but the base would never be visible. It can form in any rock.
(ii) Laccolith - The formation of lakolith occurs due to deposition of lava between convex slopes in the form of vaulted rocks, especially in the middle of layered rocks.
(iii) Phacolith - At the time of volcanic eruption, the façades are formed by the formation of lava formed by the adoption and solvation of the mountains.
(iv) Lopolith - When lava deposits form in a shallow basin with a concave gradient below the surface, its shape is called Lopolith.
(v) Sill - At the time of volcanic eruption, when the lava cools by entering between layers of metamorphic and sedimentary rocks, that shape is called sil. Its deposition thickness is quite high. In contrast, thin cob is called a sheet.
(vi) Dyke - Dyke is the deposition of slag found vertically and thinly in contrast to the cob and sheet. It can be from a few centimeters to several meters thick. Erosion has less effect on it than its nearby rocks and for this reason it sometimes appears above the ground.
(B) Hypabyssal - Igneous rocks This type of rocks is formed by solidification of cracks, holes and ducts in the path of lava at the time of volcanic eruption. They are formed below the surface of the earth but sometimes they appear above due to erosion. These rocks are found below the surface in the following forms
(i) Batholith - Lava deposits form in a very steep, sloping domed form below the ground, especially in mountain areas where volcanoes are active. Due to erosion their upper surface becomes visible but the base would never be visible. It can form in any rock.
(ii) Laccolith - The formation of lakolith occurs due to deposition of lava between convex slopes in the form of vaulted rocks, especially in the middle of layered rocks.
(iii) Phacolith - At the time of volcanic eruption, the façades are formed by the formation of lava formed by the adoption and solvation of the mountains.
(iv) Lopolith - When lava deposits form in a shallow basin with a concave gradient below the surface, its shape is called Lopolith.
(v) Sill - At the time of volcanic eruption, when the lava cools by entering between layers of metamorphic and sedimentary rocks, that shape is called sil. Its deposition thickness is quite high. In contrast, thin cob is called a sheet.
(vi) Dyke - Dyke is the deposition of slag found vertically and thinly in contrast to the cob and sheet. It can be from a few centimeters to several meters thick. Erosion has less effect on it than its nearby rocks and for this reason it sometimes appears above the ground.
2.Extrusive igneous rock: When a liquid and hot magma or lava material solidifies on the surface and forms a rock, the rock thus formed is called externally formed igneous rock. It is also called volcanic rock. Since the lava freezes soon after coming out, the texture of the rava is very fine. Basalt is the prime example of this type of rock.
Igneous rocks can also be classified into two parts based on chemical structure:
Acidic igneous rock
1.These contain more than 65 percent silica content
2.Their color is light yellow and they are relatively light. Their density is also low.
3. It is also called silica-dominant rock.
4.The amount of quartz and felspar minerals in them
More and ferro-magnesium content is less.
5. Granite and rhyolite are prime examples of this type of rock.
Alkaline igneous rock
1.They contain less than 65 percent silica content.
.2 Their color is deep and they are heavy. Their density is also relatively high.
3. Due to the predominance of ferro-magnesium in them, they are also called ferro-magnesium predominant rocks they lack Felspar.
4. Greybrow and basalt are prime examples.
Characteristics of igneous rocks Their main features are:
Igneous rocks are hard and water enters them with great difficulty through joints. Therefore, the effect of chemical weathering on them is less. Their weathering
mainly by mechanical and physical methods. Generally, igneous rocks are rough and granular. The size of the beans is that of the magma being cold depends on speed and location. Layers are not found in igneous rocks and are fossil free. Most igneous rocks consist of silicate minerals. It contains precious minerals like iron, gold, silver, aluminum etc. Their distribution is mainly found in volcanic regions.
Economic significance of igneous rocks
The economic significance of igneous rocks are as follows:
1. These are deposits of rocky minerals and most of the metallic minerals are found in agrarian rocks.
2.These include economically important minerals - magnetic iron, nickel, copper, lead, zinc, chromite, manganese, tin, etc.
3. Rare minerals like gold, diamond, platinum are also found in these rocks.
4. Igneous rocks contain more iron and magnesium-containing silicate minerals. There is some amount of asbestos in them. The older rocks of the vast Indian peninsula contain a plethora of these riveted minerals or metals.
5. Basalt and granite rocks are used for building and road construction.
6. Weathering of agrarian rocks results in the formation of black soil. This soil is more suitable for cultivation of cotton and some other crops.
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