Lecture 07

Namaskar. So, previous lecture we talked about the three cycles, main hydrological cycle, rock cycle and tectonic cycle, how they are interconnected. So, this figure is explaining about the tectonic cycle. So, let us move to the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. So, this is the plate tectonics part. 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So, this was also a confirmation for this theory that these plates used to be in the same area at the same time. The climate of this area was also different at that time. And gradually, the movement of this area started, as we said that India moved towards this direction. Secondly, the climate of this area was similar to that of Antarctica. So, this portion was close to Antarctica. And now, if we look at Antarctica, there are a lot of glacial activities there. We also talk about polar ice there. So, if this area was close to Antarctica, for example, if we take this area of India, then this area was very affected by glacial activity. So, glaciers would have been here and it would have been very cold at that time. So, some landforms and some plates moved and some remained there. So, it was also found that when glaciers move, they rub against the rock surface. So, this was another indication in these plates that such indications were found. That means, there was a glacial environment here in the past. So, this is also a very important thing. So, if we look at the continental drift, the supercontinent Pangea began to break up about 225 to 200 million years ago. This Pangea began to break up about 225 to 200 million years ago. And it was divided into fragmented pieces. So, this is a complete chart that tells us about 225 million years and it goes up to the present. It goes up to the present and shows the present situation and location of the different continents. So, if we start looking from here, what is called Pangea, then there was Eurasia, Laurasia and Gondwana land. Then this movement began. So, from 225 to 200 million years ago. And along with this, there is also its age and this geological period is also given. What was this? It was called Triassic, here it was called Permian, then Jurassic came. So, it is around 135, this is the 65th Cretaceous period and present day. So, India, as I said, it was here first, then it started moving more, then it went up more, then it came near the equator and then it crossed the equator. So, this is a complete picture and it is based on your geological findings and paleontological findings. Which we talk about the studies of flora and fauna. Now, we will see how it happened and how it started spreading out. So, we have a short cartoon movie that explains it to you. And the second important thing is that this Laurasia and Eurasia, which used to encircle, it was called Tethys, but which was on this side, towards the west, it was called Penthalassa. Now, let's move on. So, this thing that we talked about, if these plates were together, then its flora and fauna were also very similar. So, if the continents are joined, the occurrence and distribution of fossils, animals show a definite patterns about their remains. And the remains that we find here, because of this, we get the idea that not only by matching the boundaries, we can tell that the continents were together, but your flora and fauna were also very similar at that place. This is the present location of all the plates that we see now. If you look at Google Earth, you will see it very well. So, my suggestion is that if you want to see it in detail, how the seafloor and spreading centers look like, how the mid-oceanic ridges look like, and how the plate boundaries look like, then you can see it on Google Earth. You can download it on your mobile and see it. Now, these boundaries that we have created, for example, we have created a boundary here. This is a plate and this is a plate. These two are colliding with each other. But this plate, which is an oceanic plate, will go below it. Why will it go? Let's talk about that. Here, this plate and this plate are colliding. And the Indian plate and we call it the Eurasian plate and the Tibetan plate, these two are colliding. So, why will it not go down? Let's talk about that. So, this is also a boundary. If you extend it, then this boundary comes like this. Here. Then there is also a boundary here, but these plates are not colliding with each other. They are going away from each other. So, this is also a part of you. And recently, we will talk about this later. Recently, we got evidence that a very deep crack is forming here in this area. So, what is that crack? And it has also been said that a time will come, because this crack is developing, because these two parts of this plate are separating from each other. So, a time will come when a bigger crack will form here and these two continents will separate. So, this portion will be cut off from this portion. Similarly, this is also a very prominent boundary. You can see it here. So, what is the importance of these boundaries? And in this, if it is colliding with each other or one plate is going below the other plate, then what will happen in this? Pressure will be created. And due to the formation of pressure, your earthquakes will also come. Because earthquakes are what we call sudden release of stored energy. Due to pressure and stress, it is caused by both forces, due to tectonic forces and plate movement. And when it is released, we feel it as an earthquake. It is a sudden release and it creates strong vibrations. Along with that, another thing is that this lithospheric plate is given here. So, this is your lithospheric plate configuration.