[Music] Hello friends welcome to another video of Z AIS and today we will discuss the process of formation of Himalayas now this whole lecture on the process of formation of Himalayas we have divided it into three parts in the first part we will see how different parts of Himalayas were formed how this th Himalayas greater Himalayas lesser Himalayas and calic we have found in the second part of the video we will see that what are folds how are these folds created in Himalayas and what are boundary fults which separate these different parts of Himalayas and
in the third part we will see what are syntaxial bands and why Western Himalayas are wider than Eastern Himalayas to understand the process of formation of Himalayas it is important that you understand how different type types of plate boundaries interact with each other we have discussed this topic in detail in this video so this video is kind of a pre prerequisite to understand the process of formation of Himalayas we know that around 200 million years ago all the continents were one continuous land form which was called Pangia but slowly due to the movement of plates
all these land masses got separated from each other our Indian plate which was part of gondwana land also got separated from the gondwana land and it started to move in the northern Direction This movement in the northern Direction continued until our Indian plate collided with the uraan plate and because of this Collision we see himan mountains at the boundary of collision of our Indian plate and uraan plate now before going to the formation of Himalayas let's try to understand what was the role of reunion hotspot in the process of formation of Himalayas reunion hotspot is
a hotspot in our Indian Ocean line over here now this hotspot was dominant for several million of thousands of years now as our Indian plate got separated from the African plate Antarctic plate and Australian plate our Indian plate started to move in the northern Direction but as soon as our Indian plate came over this reunion hotspot it became active the reunion Hotpot started to give out lot of magma and because of this magma coming out of the reunion hotspot it melted away a large part of our Indian plate therefore reducing the thickness of our Indian
plate we can see that here the thickness is this much but after passing over the magma from this hot spot the thickness is reduced now since the thickness is reduced the weight of the Indian plate is also reduced so after passing over the reunion hotspot our Indian plate it started to move with a very high velocity you can see that it started to move by 15 cm per year and because of this the Collision was very forceful and it gave rise to the Himalayan Mountains so you can see that the reunion hotspot increased the velocity
of our Indian plate by melting away a lot of mental from our Indian plate thus reducing the thickness of our Indian plate and increasing its velocity now here we can see the cross-section of Eurasian plate Indian plate and the thees Sea here there's asthenosphere and all these plates are moving over this asthenosphere now as our Indian plate was moving towards the uran plate some part of this thees ocean plate it was subducting and because of this subduction we see that the parts of the uran plate were uplifted and this led to the formation of tibetian
plate and we can see here that the tibetian PLU was formed by the subduction of this ttis ocean plate under the uran plate it was formed much before the process of collision started and it was formed from the part of urin blate now we have already seen in our previous videos that at continent ocean boundary the oceanic plate will start to subduct because the OIC plate is denser and therefore heavier but this OIC plate which is subducting has lot of water in it and this water reduces the melting point of the Rocks therefore at the
boundary we see that lot of magma is formed because of the heat and pressure generated by subduction this magma is hot and less denser therefore it rises through the continental plate you can see here that this magma is rising through the continental plate now as this magma rises through the continental plate and it comes to the surface it starts to form volcanic mountains and a very similar thing occurred in the Himalayan region we see that this teis ocean plate which was subducting it created magma because this is also an oceanic plate there is lot of
water in it and because of this water the melting point of the Rocks is reduced magma is produced now this magma is hot and less dense therefore it will start to rise up slowly this magma will rise through this overlying continental plate and it will reach the surface and at the surface it will form volcanic mountains so we can see a chain of volcanic mountains all along the uraan plate boundary and these mountains are what we call as trans Himalayan Mountains so all our trans Himalayan Mountains are mostly volcanic in origin the karakura mountains and
the ladak mountains are example of the trans Himalayan mountains which are volcanic in nature or which we having volcanic origin now here we can see that the trans Himalayan Mountains mainly have volcanic origin and there is large amount of bolth at their base the trans Himalayan mountains are made of granite which is an intrusive ignas rock as well as volcanic rocks karakura mountains and ladak range is an example of this and also kalas range is just an extension of ladak range so here we can see that the trans Himalayan ranges mainly have volcanic Origins and
there is large beolit at their base now slowly as our Indian plate continued to move the tees oceanic crust got squeezed between the continental plates of uraia and our Indian plate and therefore some part of this teis ocean plate was uplifted and it gave rise to the Tean or tibetian Himalayas now in some books the trans Himalayan Mountains and Tean Himalayan mountains are together termed as trans Himalayan mountains but both of them has different origin you can see that the trans Himalayan Mountains were having volcanic origin they were formed from the rocks of this uraan
plate while the mountains are formed from the Tean ocean and therefore the origin of both these mountains are different now this Tean or tibetian Himalayas was formed by the Tes ocean crust therefore it has lot of sedimentary rocks because in oceans we find lot of sedimentary rocks moreover because the sedimentary rocks came from thean it contained lot of fossils of animals therefore the Tean Himalayas have lot of fossils so here we can see the characteristics of tan or Titian Himalayan Mountains they were formed by the upliftment of tees oan a part of the tees ocean
crust was uplifted now they are mainly formed of metamorphosed sedimentary rocks so these sedimentary rocks came from the oceanic crust of theis oan but during the process of elevation or upliftment they got metamorphosed now because these rocks were formed from the sedimentary rocks of ocean therefore they are rich in fossils jar mountain range is an example of the Tean or tibetian Himalayas now here you should see that this dark part is actually also a part of our Indian plate this is the Continental self of Indian plate so our Indian plate actually extends till this part
and this part is under the ocean now as the Indian plate moved in the northern direction we saw that this Continental self as well as some part of our Indian plate got uplifted and they formed greater Himalayas Whenever there is folding a for dip like this is created this is for every layer of folding so whenever there is a folding we will see that such kind of GrooVe is created in the plate in the region behind the folded part this region is called for deep now here we saw that the greater Himalayas when uplifted included
some part of our Continental self now we know that the Continental self is also reach in sedimentary rocks therefore the greater Himalayas also contain large amount of sedimentary rocks they also contain large amount of granitic rocks because it was formed from the Indian plate and Indian plate was mainly formed of granite and therefore we see that there are granitic rocks in the greater Himalayas and and because of the Continental self and the sedimentary rocks from the Continental self which formed part of Greater Himalayas we also see that large amount of fossils can be found in
the greater Himalayas the fossils are not as abundant as the thean or tiban Himalayas but still we find large amount of fossils in Greater Himalayas here we can see the characteristics of Greater Himalayas so they were mainly formed from continental crust of Indian plate so this was the first part of alayas which was uplifted from the Indian plate earlier we saw that the trans Himalayas were part part of uian plate while the Tean Himalayas were part of the teis ocean crust so the greater Himalayas is mainly composed of crystalline ignas and metamorphic rocks now they
are crystalline rocks because when this greater Himalayas were uplifted there was large amount of pressure and temperature which caused crystallization of rocks similarly this pressure and temperature also caused the metamorphic rocks and some of the ous Rocks which intruded in the formation of Himalayas in the greater Himalaya part they created ignas base now here we see that the metamorphic rocks can be granite seist and Genesis so the seist is basically formed mainly from sedimentary rocks and there are sedimentary rocks because the PED part included Continental self remember the greater Himalayas are the first part to
be uplifted from the Indian plate so the margin of Indian plate that was the Continental self which was uplifted to form this greater Himalaya so it includes lot of sedimentary rocks and these sedimentary rocks also got metamorphosized because of the large amount of heat and pressure generated during the process of AFF liment a large amount of fossils can be formed and Mount Everest is a very good example of it where you can find marine fossil all around the Mount Everest they also have granitic rocks why because the Indian plate was mainly formed of granite and
the greater Himalayas were found from the Indian plate therefore they have lot of granite Granite is also formed by inclusing magma so during the process of formation of Himalayas some magma intruded this region and when they cool down they formed granite rocks which are intrusive ous rocks now here we can see that the te ocean crust has complet subducted now the continental plate is subducting and because this continental plate does not have a lot of moisture or water so you can see that the supply of magma has stopped over here and there's no active volcanic
activity going on now as this process of movement of Indian plate in the northern Direction continued we see that the compressive forces started to create the Lesser Himalayas so this lesser Himalayas were completely formed from the the Indian plate and here we can see the characteristics of lesser Himalayas so they mainly consist of metamorphosed sedimentary rocks so on the surface of the Earth there were many sedimentary rocks some sedimentary rocks came by the erosion of the greater Himalayas and they also contain some amount of volcanic and granitic rocks obviously some magma intruded in this region
and it formed this volcanic and granitic rocks now the sedimentary rocks of lesser Himalayas do not have fossils because when these lesser Himalayas were uplifted there was not much or not Abundant Life forms in this region and secondly most of the Rocks got metamorphosed so the fossils got destroyed now as this subduction continued the compressive forces kept on acting on our Indian plate and they led to the formation of civa Leake the Sia Leake where many main formed from the Rocks which were eroded from the Lesser Himalayas and therefore we see sedimentary rocks in siiva
now when the cival were uplifted there was large amount of life form in this region and there were a large number of mammals so we see evidences of mammal fossils in the calik moreover whenever there's a fold formed we see that a for is formed in the area behind this folding region this for D is like a Groove in our Indian plate so this was a for diff along the boundary of Cales later on the erosion of Cales as well as the erosion of Peninsular region it filled this part to form Indo gantic and brahmaputra
plains so here we can see how all these other Himalayas as well as gtic Plains were formed now if we see the cross-section of Himalayas from here then it would look something like this here we can see that trans Himalayas this is the volcanic mountains which are formed along the boundary of uran plate just after it we have indas tangu suure zone or indas suure Zone in this Zone basically our Indian plate it touches the trans Himalayan plate now here we can see the Tean Himalayas so you can see that basically the tan Himalayas align
over the Indian plate the Indian plate goes below the thean plate and it comes in contact with the uran plate over here and therefore this boundary is called in the the San and here is the Tean Himalayas here we see the greater Himalayas and then lesser Himalayas and the siales we can see that the thian Himalayas and greater Himalayas are much wider compared to lesser Himalayas and sial Leakes here we can see the characteristics of Cales the the calic were formed by sandstone and mudstone set from the Himalayas so as we have discussed that with
the appli of lesser Himalayas there were Rivers which eroded the Lesser Himalayas and brought the sediments and they deposited over here and this region when got uplifted it included all those sandstone and mudstone which were brought by the erosion of lesser Himalayas and these rocks have lot of fossil of mammals because when they were uplifted there were lot of mammals in this region so far we have seen the cross-section of Himalayas now we will see the top view or we will try to understand how these different regions are spread along the boundaries of Indian plate
and uran plate so here you can see that when the Indian plate came close to the uran plate the Tean ocean plate it started to subduct under the uran plate and it formed the Titian PL slowly this process of subduction continued and we see formation of volcanic mountains all along the border of the uraan plate and these are our trans Himalayan Mountains further we see that this process of subduction continued and we see that the te ocean crust it uplifted to form the Tean or tibetian Himalayas now our Indian plate it went below the Tean
Himalayas and came in contact with the uian plate so this region where the Indian plate comes in contact with the uran plate is called IND the suture zone or IND the Tano suture Zone further when this process continued we see that the Indian plate part started to uplift and we got our greater Himalayas so you can see that both thean Himalayas and G Himalayas are much wider the process of compression further acted and they led to the formation of lesser Himalayas and you can see the district distribution of lesser Himalayas from Pakistan to Myanmar finally
in the last part we see that there was a formation of siales in the southern direction of the Lesser Himalayas and both these lesser Himalayas and shales are relatively thinner compared to Greater Himalayas and Tean Himalayas lastly because of the sediments which were deposited from the Lesser Himalayas as well as from the peninsula we see formation of gantic plains and here we have already discussed that there was a for de form so whenever a folding occurs at the back end of this folding in the plate we see a Groove like structure which is called for
deep so these deposition in the for deep created the gtic planes thanks for watching the video and if you liked our video then do subscribe to our Channel and if you like the content we are creating and you want to contribute then you can use the QR code shared in the video