Lecture 01

Namaskar, so this course is being given for the first time in Hindi, although as I said in my intro video that this course is very popular and it has been re-run many times. So this time we will try to speak in Hindi as much as possible so that more and more people can benefit from it. This course is Earth Sciences for Civil Engineering, although I will speak in English in some parts because there are some terminologies which will be correct in English only. So in this we will try to know about the earth processes. So let's move forward slowly and see what we will be able to learn in this. So this is my address below and email id. So whoever needs it, there are TAs in this, so they will also help you. So you will also get their details. But if you have any such questions, then you can also write to us and TAs also. First write to TAs, then we will write to you. So this is called an attempt to understand the dynamic earth. Because the earth is such a planet in which the Jeep and we have also got a means of living and we are also able to live in it. But along with this, the processes of how this earth is made and we will also know about it. So as we move forward in this, what will be the course content? What topics will we talk about? What lectures will be there? So first of all, what is the importance of geoscience or earth sciences in civil engineering? And why should we look at it in detail? Although I have also said before that we will not talk about civil engineering in this. But yes, we will talk about some such projects which are related to earth sciences and those projects should be taken there, construction projects basically. Should we do it there or not? Why should we not do it? We will also know about it. So about this, we will see what is the importance of geosciences or earth sciences in civil engineering. So first of all, we will start with plate tectonics. The landscape that we have created, the surface and the mountain ranges, or if we take the Indo-Gangetic plains, how did it come to be? And if we look at it for India, for the Indian plate, then we will say that how did our Himalaya come to be? And what was the reason for the formation of Himalaya? And what are the advantages and disadvantages of it? We will also talk about that in this. So there are some processes related to plate tectonics. And your rock cycle is interconnected with this. The various types of stones that have been formed, which we call igneous rocks, metamorphic rocks, sedimentary rocks, how did they form? How is that process of formation related to plate tectonics? We will also learn about this in this. And in whatever lectures there will be, we will give you its information, so that you can understand it in detail. So one is continental drift. Where was this Indian plate before? And where did it start from? And why is there movement? And what features have been created due to this on the globe? What features have been created on the entire earth? How did the landscape evolve? We will talk about that. And what are the different types of plates? Because there are not all the same types of plates. We call them different. And mostly there are two major plates. That is the oceanic plate and the continental plate. We will talk about that. Then I will take a basic lecture, which has two or three lectures involved in it. These are rock forming minerals. Because the rocks that we have formed, of different types, which I said we call igneous, sedimentary, metamorphic rocks. From which process are they formed? And what are the minerals in these rocks? And what is the importance of these minerals? We will also talk about this in civil engineering. Because every mineral has a different hardness and durability. And the most important thing in civil engineering is that we talk about rock strength or shear strength. So are the strength of the rocks different from each other? And because of the mineral composition, the strength of the rocks are different? We will talk about this as well. And these rocks, the igneous rocks, sedimentary rocks, metamorphic rocks, on what basis will we identify them? What is its texture? What kind of shape is it? We will not talk about its shape, but what are its surface expressions? And what are its properties? And as I said, when we talk about plate tectonics, we will talk about its implications in landscape formation. What is its role? And what kind of landscapes are formed by it? And in the upcoming lectures, we will talk about how the landscape will change in the future. We will try to talk about it to some extent. And when we say that our Himalayas are formed, then the Himalayas have brought us some benefits as well as some losses. And we call those losses as hazards. And what are the consequences of this? What are the natural hazards? These are also called geological hazards. So what are the hazards that we have to face? Now, if we talk a little about this, so when the Himalayas started to form, we got a monsoonal climate. We did not have this season before. So we got monsoon. We got erosion due to monsoon. Our Indo-Gangetic plain was formed due to erosion. Rivers were formed. Water began to flow in our rivers. Major river systems were formed due to it. But when we talk about plate tectonics, one plate is colliding with another plate. And because of that, your Himalayas are formed. So if we sketch this a little, one plate has gone down like this, and one plate is right. We will talk about which plates are these later. But now finally, the situation is that both our plates have started colliding with each other. Because of the collision, your Himalayas are growing. So what are the benefits due to this? As I said, we got monsoon because of this. But the collision is happening continuously. So because of this, we have hazards. One is earthquake. Second is floods. There are landslides too. We will talk about this too. And what do we have to learn from this? We will discuss about this with other science processes. Then, we are saying that this is deformation. And because of deformation, different geological structures are formed. Two plates are colliding with each other. One plate is going down. You will understand more about this when we talk about plate tectonics. But we call it geological structure. It is believed that whatever deposition happens, the sediments deposited will always be in horizontal fashion. It is deposited like this. Now, if you put it in a compressional regime, pressurize it, it will start folding like this. There will be folding too. And along with that, the layers will deform like this. We call this basically geological structure. We call this fold. Suppose, this gets fractured. There is a crack here. I want to say this in a simple language. But we will say that it gets fractured. Or there is a crack in it. Usually, we call crack as fractures. But if there is a displacement in it, some layers go up, it will look like this. This is your displacement. We call this fold. As I told you, we will see this in detail later. Then there are joints. What are the unconformities? In engineering, a word is used, discontinuities. We call it, this word is used. These discontinuities, basically we call it, these are the discontinuities, in which there are folds, joints. Because this is a very important aspect for civil engineers. Because if these structures are present somewhere, they directly influence your shear strength. It weakens the shear strength of any material. We will pay more attention to this when we talk about geological structures. As I said, we will also look at earthquakes because this is an associated process which is related to plate tectonics. We will talk about seismology and earthquakes. In which magnitude, intensity, seismic hazard and earthquake prediction. Are we still standing on it or not? We will also try about this. But mostly, we will try to study about magnitudes. Are there different types of magnitude of earthquakes? What is the meaning of intensity? And what is the related hazard? How much area will be affected by these earthquakes? Although, in the last few years, in the last 10 years or 20 years, there have been many earthquakes in this country. And recently, the biggest one, the destructive one was in Turkey. So, that is also an earthquake which has affected many people. The damage is mainly due to civil structures. How people died is due to structural damage. Houses have been destroyed and total destruction is due to that. So, what do we learn from this? Are we all safe in India? And if we are affected, how much area will be affected? Why will it happen? We will also study about that. So, we will study more about the rocks, the soils, the physiography. Are there mountain areas or plain areas? What is the effect of this? We will also study about this. Another problem that we always face is the landslide. So, wherever your slope is available, plus you have water with it. So, where will the water come from? It will mainly come from the rainfall. So, if these two things are needed, and as I said, if you have a slope, then it is absolutely certain that there will be a landslide. Provided that the shear strength of your material is good, then there will be no problem, there will be no landslip, there will be no landslide. But if your shear strength is low, then this will happen. Now, a recent example, I am giving you again, we are talking about the Joshi Mat. We will talk about it to some extent, although we will not comment on it much. But why did it happen? And could we have stopped it? We had so much technology, so much understanding, that we could have stopped it. Geologists or earth scientists, along with civil engineers, could they have stopped the disaster? It would have been necessary if we had removed the people from there in advance. If we had understood this, then to some extent, we had understood that this could happen. But why was it not done? We will not talk much about it, but it is okay. The second thing is that, along with landslides, we call it subsidence. And to some extent, in the Joshi Mat, both these things have happened. It is not just the Joshi Mat, if I remember the correct name, there is a village called Doda, when it comes to Kashmir, there too a similar situation and experience has been experienced. So, we will classify it broadly, that is what we call mass wasting. So, this is also an important topic. Along with this, as I said, landforms are very important for us. Where should we settle people? Where should we not settle them? Why should we not settle them there? Until we understand these landforms and their processes, which we call surface processes, we will keep making mistakes. Our country's population is increasing. So, most of the examples we will talk about by combining foreign and national examples. So, if we want to understand our processes and how landforms are being made and how they will be made and how they will be spoiled, if we want to understand this, then we will make mistakes. And that what we call is that we are exposing ourselves to hazard. What is hazard? Basically, it is that if we are being harmed by it, then we will go in front of it. So, we have to be harmed. So, it is very important for us to understand this. Then we will talk about environmental geology. Although we will not go into too much depth, but we will touch it to some extent. But environmental geology again is that it is related to the whole environment. And if we look at it in detail, then if you intervene in any process, the other process will be affected. So, it is important for us to understand this connectivity. So, when we understand about earth surface processes and landforms and when we understand about this environmental geology, then we will be able to make our major constructions in a safe location. We will be able to do that. But we have talked about dams and tunnels here. Where do we have to do waste disposal? This is also a big problem in our country. If we talk about this, if we talk about waste disposal, let us first say that dams and tunnels are being constructed a lot now. Infrastructure development is happening a lot in our country. So, it is important that where the dams are made, where its location is, we have to have knowledge about rocks and environmental geology in both these things. Where do we have to do disposal? Waste disposal. A lot of waste comes out of houses. So, the biggest problem is if we look here, there was a lot in the news that there are huge mountains of waste disposal in Delhi. So, is it right to put it there? What is the overall effect of that? I will give a little information here that if we have waste disposal, then whatever garbage we have, the level at which it is kept, the water that comes from the rain and whatever happens, it will not cause seepage. What effect will it have? We will say directly that it will affect the environment. So, basically when we say that the sites of waste disposal should be idle, then we are not talking only about the waste that comes out of our daily routine house, but there is also nuclear waste in it. We should also keep it in an appropriate place and dispose it. So, for that you should have knowledge of geological structures, what kind of rocks are below it, you should know about it, what is there there, and your groundwater will be most affected by it. So, this is a long-term effect. You will not know immediately, but if it continues for a long time, then it will affect the coming generation. Because our residential areas depend on groundwater. So, we will try to understand all these things and it is possible that in the future we will discuss some other topics that will be useful for you. These are some books that you can refer. However, I would say that whatever literature we give you, whatever slides we give you, whatever we talk about, that will be enough, but if you want, then you can refer all these books. And if you want, we have a soft copy of it, but we will not be able to give it to you. But still we will try to provide you with the maximum things so that it is easy for you to understand it. These are some very interesting textbooks. And we will also refer these textbooks when we are giving our lectures. Let us move on. So, if we look at the earth, the planet, then the first look at the planet earth, what does it show? The first question is how was it formed? This is a spiral figure in which it is shown the origin of the solar system. The age of the earth is 4.6 billion years. It is dated with uranium-thorium, radioactive elements. It is dated. Its age is 4.6 billion years. But what happened after 4.6 billion years? This whole spiral is shown in this picture. Some events are also told in this. For example, Jurassic Park also had an event. In this event, it also happened that there were some events in which volcanic eruptions occurred due to which the temperature increased. And due to the increase in temperature, all the creatures that were there at that time were completely destroyed. That is what we call extinction. You can also see that in this picture. Anyway, we will talk in a lecture about when these major events occurred. When I teach Volcanoes, we will talk about when these major events occurred. It is not that there were no climatic changes before. And since the impact of volcanic eruptions, the climate has changed. Although we are triggering it more, but in earlier times, and millions of years back, there have been changes in the earth's climate. The most important period for us is this period, which we call the Quaternary Period. And in this Quaternary Period, there are two other subdivisions which we call epochs. The Holocene Epoch and the Pleistocene Epoch. At this time, the most changes have been seen because the Holocene Epoch is said to be 10,000 years old. It is said to be present from 10,000 years ago. The most changes will be seen in this because this is where modernization has taken place. And the evolution of man has been shown to you that this is where the most changes have been seen. So this entire Quaternary Period is said to be 1.8 to 2 million years old. So this is it. But if we go back to 4.6 billion years ago, when the earth was there, this first became the solar system. After that, there is an event called the Big Bang Event, which is said to be 12 to 15 billion years ago. And when this explosion happened, it produced atomic particles that later formed galaxies, stars and planets. So from this, our entire galaxy was formed. Stars and planets were formed because of the Big Bang, which happened 12 to 15 billion years ago. After that, it is said that this kind of process took place, which happened 7 billion years ago. Another explosion, which is called Supernova, which is shown here. So this was another event. And lastly, when we say, we are moving it like this. So lastly, the origin of the solar system at around 4.6 billion years ago. So in that, our earth was formed and all the planets around it were formed. So these are some of the information from which we are starting. So that we can easily, slowly, try to understand the overall process. So my aim was to start with the solar system. As I said, there is a geological time scale involved in this. From where we start, from pre-Cambrian to Cenozoic. There are different eras and different periods. We will give you a slide in which this is written in detail. Now, let's talk about Earth's resources. So no other planet in the solar system currently has the right chemical and physical mix needed to support life. There is no other planet like this. There is a lot of research going on in Mars as well. We were looking at a PhD student's thesis. There are some landscapes in Mars which are similar to Earth's, with water and water's influence. But there, there is no precise chemical composition or the effect of the solar system. So the kind of life support that we are getting here is not available there. Secondly, no conclusive evidence of life existing elsewhere in the universe has yet been discovered. I will stop here. We will meet again in the next lecture. Thank you. Namaskar.