Geography | Rocks | Classification of Rocks | Igneous, Sedimentary & Metamorphic | Crazy GkTrick

0:11 Hello friends, welcome to our online platform Crazy GK Trick, I am Dinesh Sahu and in today's video lecture, we are going to discuss a very important topic under World Geography. The name of the topic is rocks or rocks. You must have often heard igneous rocks, sedimentary rocks, metamorphic rocks, so the names of these three types of rocks that we get to hear, we will discuss these rocks in detail, how these rocks are formed, what are their properties and what type of questions we get to see from this topic, so the video lecture is going to be very important, you must watch the video lecture till the end. Okay, apart from this, before starting the topic, I would like to give you a little update, if you want to study geography by joining me, then you can download our root application from Play Store, here

0:58 you will also get different foundation courses and you will also get recorded and live foundation courses of my geography, so here you can join me and get live and recorded batches of my geography. You can read Geography by joining me here. Let's start the topic directly without any delay and first of all we understand what the rocks are or what are the rocks or what is their definition. So look, now the rocks are there, you must have seen the rocks. The crust of our earth, which is a look, you get to see three layers on our earth. There is one upper layer which we call crust. We call it Krishna or we call it the crust. There is a middle layer called mantle.

1:47 And then there is the core. There are three layers only. When we study the inner structure of the earth, we mainly study these three layers. The upper crust, the mantle and the core. So this is the uppermost surface. So here only you will find rocks, something like this. So what do we call them? Rocks or rocks, so its definition. What could be the case that the collection of minerals means the collection of minerals means that these rocks are made up of minerals. Now what are minerals? So you know that in our earth's crust, there are many elements and components or which

2:33 elements are found. Like the most oxygen is found, silica is found, aluminium is found, iron is found, in this way, many elements are found in our earth's crust. So, these elements that I have told you or these elements that are the oxides of these elements, silicates, carbonates, what do they form when they combine together, they form minerals. And what do we call them? We call the collection of these minerals rocks. You have to remember. So, I think the

3:18 definition of rocks must have become clear. So, minerals will be found here and you will also find fossils in it. You have to remember this thing too, although you will not find fossils in every type of rock, like fossils are not found in igneous rocks, but still you will find fossils in some rocks and not in some. So you must have got a little clear definition of what is called rocks. So just remember one line, what do we call the collection of minerals, we call them rocks and the rocks that we study, when we study them, what do we call it, we call it petrology, remember petrology, okay, the study of rocks is called petrology, so

4:05 you have to keep this thing in mind a little bit. I think you must have got the definition of rocks very clear, let's discuss further, when we talk about their types, okay, if we divide them on the basis of their origin or on the basis of chemical composition, then we mainly get to see three types of rocks. So which rocks are these, then first of all there are igneous rocks or or Igneous rocks. Okay. Second are sedimentary rocks or we call them sedimentary rocks and then there are metamorphic rocks. Now we have to study these rocks one by one. How are igneous rocks formed, what are their properties, how are sedimentary rocks formed, what are their properties

4:50 and what are metamorphic rocks, what are their characteristics or properties. So remember that we get to see three types of rocks, igneous, sediment and metamorphic. Okay. Let us discuss these rocks one by one. First of all, let us look at igneous rocks or igneous rocks. So, see, you must know what is above our earth, the crust, or when we study the internal structure of the earth, the crust and the upper layer of the upper mantle, what is this? It is the crust and this is the upper layer of the upper mantle. Okay, this is the crust, okay and this is the upper layer of the upper mantle. This part that I have made is the

5:41 upper layer of the upper mantle. Na, did you understand the upper layer? You know there are three layers, crust, mantle and core. So we have taken the core completely and the uppermost layer of the upper mantle, if I tell you in simple language, then both of these together are called lithosphere. We call it lithosphere or we call it lithosphere. Did you understand the point? And the upper layers of the upper mantle are collectively called

6:26 lithosphere or lithosphere. If we talk just below this, then here you will see what do we call it in this region. What do we call this region? We call it asthenosphere. We call it asthenosphere. It means that within the mantle itself, you get to see a place which we call asthenosphere or we call it athenova. Is it filled? ... What happens is there are a lot of convection currents, okay, under this magma, if you see in this way, then convection currents flow, convection waves flow,

7:14 you have to remember, that is, you understand in simple language that the magma which is filled in the mantle inside the earth, it always tries to come up because the temperature inside is very high, the pressure is very high, I am trying to explain to you in very simple language, so it always tries to come up and this lithosphere of ours, children, here you will also see a lot of cracks, some cracks reach up to the top, some cracks reach up to half the distance, like this, okay, so if this hot magma gets space from anywhere, then it will come up upwards through a volcano, through a rapid explosion, when this hot magma comes up, then we call it lava, that's clear and what happens in some conditions, this lava, suppose there was a crack here and this lava

8:00 tried to come out from inside and it cooled down inside and solidified in a particular shape, okay, so I The purpose of telling is that this hot material which comes out of the earth means this hot material which is coming out from inside the earth, we will call it lava, how will it come out, it will come out through volcanic eruption, okay and when this lava comes out, what will happen as soon as it comes out, okay, so the temperature inside was very high, as soon as it came out, what happened, the temperature suddenly decreased, okay because you will see the temperature inside can be or is 800 to 1200 degree Celsius and as soon as it comes, here it is from 15 to 20, 25, 30 depending on where this volcanic

8:46 eruption has happened, so as soon as the temperature suddenly decreases, what will happen here, this hot lava will turn into solid rocks after some time, it will get converted into solid rocks, okay and this is how igneous rocks are formed, did you understand, as soon as the lava came out from inside the earth, how did these rocks cool down When the earth cools down and becomes solid, it will take the form of rocks. So these rocks are called igneous rocks. That means the rocks which are made of hot molten material are called igneous rocks. Now if these are formed outside the earth, then we will call them externally formed igneous rocks. If these are formed on the surface, then we will call them externally formed igneous rocks. And if these are formed inside, then

9:31 we will call them internally formed igneous rocks. So this much you have to remember is clear. So, I think you must have understood about igneous rocks. Now one more point you need to understand here is that in the history of the earth, when our earth was formed, remember one thing. When our earth was formed, then our earth was like this. Millions of years ago, when our earth was formed, what was our earth? It was a ball of hot fire. You know that our earth is very hot from inside, is n't it? The core of our earth, what is its temperature? It is about 6000 degrees Celsius. But when the earth was formed, at that time our earth was very hot from outside as well. It was very hot, right?

10:19 Here also what was its temperature? It was very hot. There was hot material here. Slowly the earth started cooling. Slowly what happened with time? In millions of years, in crores of years, the earth started cooling. The earth started cooling down. And when the earth cooled down, the primary rocks that were formed, the primary rocks that were formed, so which rocks came into existence at that time? Igneous rocks or Igneous rocks came into existence at that time. So remember, in the history of the earth, the first rock that was formed on our earth was Igneous rocks because at that time the earth was hot. And when that hot material cooled down, the first rocks that were formed are

11:05 called igneous rocks. So we also call them primary rocks. Many times the question has come in the exam that which of the following are primary rocks is igneous, sedimentary or metamindus, through volcanic eruption, through central eruption, through fissure eruption, so you should remember all these points. It is about fire rock, it is clear, let us discuss it a little bit in theory, I will make it rough, okay, see how it is formed, so it is formed after the magma or lava cools down,

11:50 if it is formed inside the earth, then after the magma cools down and the lava cools down after coming up, then it is formed after the lava cools down, this is a very important point, these are primary rocks, they mean they were formed first in the history of the earth and they are formed first, then after their weathering, erosion or other chemical reactions, sedimentary or any other rocks are formed, you have to remember, okay, so this is the most important point to keep in mind according to the concept and also from the point of view of the exam, understand the next thing, okay, now when the lava came out of the volcano, suppose the lava came out, okay and what happened here, if suppose there is a living being, okay, such a hot substance whose temperature is 800 to 1200 degrees Celsius, if any living being The animal will come in the grip of this lava,

12:37 so what will happen to it, it will burn to ashes, okay, apart from this, when the earth was formed, there was no life on our earth at that time, okay, at that time fire rocks were formed, when the earth was born, there was no life at that time, okay, so fossils will not be found in it and currently when this lava is coming out through volcanic eruption and there are any living beings, animals and vegetation here, then they will turn to ashes after coming in the grip of that hot lava, so tell me what fossils will be found in this rock, will fossils be found, no, remember that fossils are not found in igneous rocks because these rocks are being formed only after the hot substance cools down, due to this reason, fossils will not be seen in it, even if there is a fossil,

13:24 it will burn to ashes, do you understand fossil, I mean see what is a fossil, suppose there is a small animal, okay, if it dies, then what will happen, its decomposition will happen gradually, decomposition will happen, right, and suppose its skeleton is now bones, which Bones are bones which do not melt easily. So what will happen after thousands of years, millions of years, gradually dust and dirt will accumulate in it, it will get buried under the rocks and suppose from today, after millions of years, if someone digs there, then we will find the skeleton of that animal, whatever we find there, we will call it the fossil of that animal. So you must know fossil, so remember that we do not find fossils in these rocks. Apart from this, you will find minerals in it, you will find minerals, you will find metals in it.

14:09 Metallic minerals are found, apart from this, layers are not found in them. Remember that crystals are found in it, right? Crystals are not found in layers. Especially, you have to remember, because what happened, lava came out and it solidified. So crystals will be found in it, particles will be found, grains will be found. What we call crystals, crystals are crystals in this way, right? Crystals are crystals in this way, crystals will be found in this way, meaning grains will be found, small and big grains will be found, but layers will not be found here. You have to remember, some examples of this. Like granite gneiss basalt grab pegum it dio it is also a question in the exam that out of the following basalt is an example of which one, gravure is an

14:56 example of which one, granite gneiss is an example of which one, so all these are examples of igneous rocks or igneous rocks, you have to remember it, okay and in the history of the earth, igneous rocks were formed first, you have to remember it, it is clear, I think you must have understood, here is another diagram where it is told about these igneous rocks, you have to remember it, once we revise how igneous rocks were formed, it is formed after the hot substance cools down, apart from this, the rocks which were formed first in the history of our earth were igneous rocks, you have to remember it, fossils are not found in it, layers are not found in it, you will see crystals will be found in it, crystals will be found,

15:42 we call them igneous rocks, apart from this, you will see in it, you will not see any holes also. You will find it because any hot substance has cooled down and solidified, you will not find any holes in it. You have to remember this, apart from this, fossils are also not found in it. The rest of the planets are ho, granite, gneiss, all these are its examples, so you should remember it clearly. I think you must have become clear about igneous rocks. If you are preparing for any exam, then each topic is important from the point of view of the exam or there is a beneficial lecture for it. You have to remember it. Next, we will discuss what are sedimentary rocks. Let's see, for example, is it any one rock? What is it? Any one rock. Now, which rock is this? Don't think about it right now. Is it

16:27 any one rock or what is any one rock? Now, what happens is that this rock is located in our earth. Now, what is falling on it? What is the sun? So, the temperature of the sun is falling on it. Rain is falling on it or it is facing rain. It is facing water, okay, when there is strong sunlight, then what will happen is that the rocks get heated, when you heat anything, its volume increases, it expands, then it will be night, then it will shrink, then the next day it will be day, then the rocks will expand and then shrink, so this process continues, okay, apart from this, it also has to face rainwater, so in this way, due to many external forces, the

17:15 surface of the rocks is facing all these external forces, what happens due to this, weathering takes place, isn't it? Weathering means breakage, meaning its upper layer has become damaged or has broken, is n't it? Weathering and the other process is erosion, okay, erosion means suppose there is wind, or the wind has deposited small particles of this rock at one place, or rainwater has come, if it rains, then the rainwater has deposited these small particles of these rocks at one place. Are there detritus particles or weathering particles, they are washed away and deposited at another place. So what happens through this process, its particles will get collected at another place, in this way one layer got collected, then

18:02 another layer got collected, now this is an event of thousands of millions of years, children, events happen over crores of years, okay, then this layer got collected here, in this way things are getting collected in the layer, now when these things are continuously getting collected in the layer, then what is happening in it, the pressure is also increasing, okay, the pressure is also increasing, suppose it rains, then due to rain water some things will change, the temperature is falling, many other processes also go on on the earth, okay, so what happens in this way, a new rock is formed, okay, what happens, a new rock is formed, what is happening in it, means remember two words, one is its solidification, is n't it, its accumulation is happening, accumulation and solidification means its solidification is happening,

18:48 after this A rock is formed which we call sedimentary rock, means the sediments after the weathering and erosion of a rock, what were these? These are its sediments, right? The rocks that are formed after the consolidation or formation of sediments from sediments are called sedimentary rocks. You have to remember and this process is what we call lithification. We call it lithification. Remember, you will get a question in the exam on what is lithification. So remember, in this way a completely new rock is formed which we call sedimentary rocks. Now how will sedimentary rocks be formed, from which rocks will they be formed, so they can be formed from igneous

19:36 rocks as well. Apart from this, they can also be formed from metamorphic rocks. Or they can be formed by changing from sedimentary rocks as well. It means any rock, it means any rock can undergo weathering and erosion. It can be igneous, sedimentary, metamorphic, any rock, any rock, the necessary process. What is the process that you need to know that after the weathering of a rock, when a rock takes a new form, we call it sedimentary rock. Apart from this, the term lithification is a term that you have to remember. Now tell me one thing, will you find fossils in this rock? Will you find fossils? Yes, you will find fossils in it. Suppose what is happening to this rock here, it has

20:22 started forming and suppose there is some animal or vegetation in between, it gets buried in between. The second layer comes on top, then the third layer comes. In between, there are remains of some animal or vegetation. There are sediments. Sorry, I am calling sediments, there are fossils of that. Or some animal or tree leaf gets buried. So you have to remember that in this sedimentary rock, you find fossils. You find fossils in the petroleum that you extract. The petroleum that you extract, the coal that you extract, the natural gases, from which rocks do you get it? You get it from sedimentary rocks only. So you have to remember that in this sedimentary rock, you find fossils. You find fossils in the petroleum that you extract. The petroleum that you extract, the coal that you extract, the natural gases, from which rocks do you get it? You get it from sedimentary rocks only. Remember what are sedimentary rocks, only after the weathering of rocks by air, water, glaciers or by their accumulation,

21:08 or through the process of lithification, new rocks are formed which we call sedimentary rocks, okay I think you must have understood, so fossils will also be found in it and you will also get to see layers in it, okay remember, you will find fossils of plants and animals in it, apart from this, coal, petroleum which is extracted, natural gas which is extracted, we get to see them only from sedimentary rocks and currently, the highest quantity of fossils is found in our earth. In this you will find only sedimentary rocks. 70 to 75 percent of the rocks on our earth are sedimentary rocks. You have to remember this. Its examples are sandstone, limestone, coal, petroleum, all these are its examples. You have to remember this. So I

21:54 think you must have understood this as well. Remember two points in this. One, you will find layers in it. We call it sedimentary rock because it is made in layers. It has a layered structure. Apart from this, we will also find fossils in it. We will also find fossils in it. Earlier, the rocks that we had read about, neither did they have layers nor were we able to find fossils in them. That is clear. Let us discuss further. Metamorphic rocks or metamorphic rocks. What are metamorphic rocks? Children, like for apple or any rock. Now, many things are working on the earth. Many external forces are working. For example, sunlight is affecting the earth. It is facing high temperature, it is facing water, so what happens to this rock, its

22:40 form changes. Metamorphic rock means form change. So you have to remember one term, in this, it is due to pressure or volume. Due to pressure or due to volume, okay, due to pressure or due to volume, apart from this, due to temperature, okay, due to temperature, when changes come in a rock due to these things, okay, due to pressure or due to volume and due to temperature, when changes come in a rock or its form changes, then we call it metamorphic rock, okay, suddenly, it means the rock is facing heat or temperature for a long time, okay, it is

23:27 facing pressure or there is a change in its volume, okay, so this creates new rocks, which we call metamorphic rocks. Apart from this, you can also understand it like this, suppose this is our lithosphere and this is our athena, but suppose there was an igneous rock, there was an igneous rock inside the womb of the earth. Okay, I told you that igneous rocks are formed inside as well. There was a crack here, suppose lava came out from the crack, ok, lava came out, magma came out and suddenly the temperature here increased, then what will happen to it, it will get transformed and it will change into metamorphic rock. Suppose there are two plates, one plate is this, one plate is this, you know that these landmasses are what we call plates,

24:15 you get to see a lot of plates on our earth, all the continents and oceans are situated on these plates, so suppose these are two plates and in between there is one or the other plate, okay, or there is some rock, now when these plates are coming together, okay, then what will happen to it, you will continuously put pressure on it, so what will happen to it, there will be pressure on it, so when there is more pressure, what will happen to it, the shape will change, okay, so it can change into metamorphic rock, it may be igneous before this or it may be sedimentary, or it may be that it itself is metamorphic rock, it may also be that it itself is metamorphic rock and due to heat, due to pressure or Due to volume, its form itself may change. So metamorphic rock can also change back into metamorphic rock. You have to remember, as we

25:01 discussed that sedimentary rock can also change back into sedimentary rock. So in this way, the pressure has increased in it and when the pressure increases, its volume will also change. When these plates apply a lot of pressure, then its volume, suppose the plates have come closer, these plates have come so close, then its form will completely change. So its volume will also change. This will also lead to its transformation. So just remember these terms that in any rock, due to pressure, due to volume and due to temperature, the form of the original rock which changes, we call it metamorphic rock or metamniotic

25:53 phylides. So it is possible that due to heat, due to pressure or due to change in volume, it may get transformed again. So slate phylides change into pentaine. It means that metamorphic rock can also be transformed back. You have to remember this. If we talk about sedimentary rocks, what kind of transformations occur in sedimentary rocks? So this is a sedimentary rock called sel. The sedimentary rock called sel changes into slate. The limestone changes into marble. A lot of questions come in the exam from here that what is the transformation of marble. So the limestone which is a sedimentary rock changes into marble. The sandstone changes into cadjite. The

26:44 conglomerate changes into karzite. The bituminous coal changes into granite and diamond. So these are sedimentary rocks and these are metamorphic rocks. Apart from this, what does igneous get transformed into? Granite gets transformed into gneiss. The basalt gets transformed into amphibolite and the basalt gets transformed into schist. You have to remember this. So questions also come from here about transformation that what will metamorphic rock get transformed into, what will igneous get transformed into or what rocks will sedimentary get transformed into or what rocks will it get transformed into. You have to remember this. So I think you should remember the three rocks that I have taught. Igneous okay,

27:30 sedimentary and metamorphic okay, I think you must have understood very well what the three rocks are, what are their characteristics, how were they formed on our earth, okay, currently these are seen in the highest quantity on our earth, when it was born, at that time igneous rocks were the most, okay, so you have to remember all the points mentioned carefully, okay, now let us understand a little more about the rock cycle, what is the rock cycle, what is the rock cycle, this is very important, okay, what is the rock cycle, what is the rock cycle, understand this a little bit, see, for example, children, this was hot magma, right, what came out of the hot womb of the earth, hot magma came out or lava came out, it cooled down, what happened, it cooled down, then what will happen, it will

28:17 take the form of solid rocks, so what will we call it, we will call it igneous rock, okay, now what happened to this igneous rock, it got broken, it underwent weathering, erosion, the process of weathering erosion took place in it, okay, so its sediments will come out, its sediments will come out and gradually what will happen to them Deposition will happen at one place and there will be a process of solidification in it, there will be a process of solidification, lithification will happen and this will form sedimentary rocks, meaning a new rock will be formed from the sediment of igneous rocks, layer after layer will accumulate and a new rock will be formed which we call sedimentary rocks. Okay, this much is clear now what is happening in these sedimentary rocks, the temperature is increasing, there is a change in its temperature, there is a change in pressure, what is happening due to the change in volume, a new

29:03 rock has been formed, its form has changed, which we call metamorphic rocks, okay, so see, igneous rocks were formed, from igneous rocks sedimentary was formed and then metamorphic was formed, okay, you have to remember now when sedimentary rocks are formed, it is possible that it may again be weathered, eroded, it may again be weathered and sedimentary rocks may again be formed, okay, let us discuss further, now these metamorphic rocks, okay, this too can be weathered and eroded to form sedimentary rocks, right? Weathering and erosion took place and sedimentary rocks can be formed here again. Apart from this, the igneous rocks that were formed here, due to change in temperature, due to change in pressure or due to change in volume, they can again turn into metamorphic rocks. You have to remember this. So this is the entire rock

29:50 cycle. You have to remember it. It is clear that igneous rocks can change into sedimentary. Metamorphic rocks can also change into sedimentary rocks somewhere. Sedimentary rocks can change into metamorphic rocks. So this is the entire rock cycle. There is a cell cycle. You have to remember this diagram. It is very important. Apart from this, if these rocks melt again, then what will they become again? They will become magma and then they can become solid and turn into igneous rocks. So this is the entire process of the rock cycle. You have to remember this. So friends, in today's lecture, we have discussed the rock system in great detail, very precisely, in easy language. I have tried to cover all the important content under this topic in a short time. I

30:37 think you will understand this. You must have understood this topic, it is beneficial from every exam point of view. I have covered every content which is important from the exam point of view. So if you liked the video lecture, please like the video and do share it with your friends. Apart from this, if you want to study Geography in detail from me, you can download the application from Play Store and here you can study Geography from me live and through my recorded courses. So, for now, that is all in today's video lecture. You will meet in the next better lecture, until then take care of yourself and keep studying. Bye Bye, Take Care, Jai Hind [Music]