The Formation of the Himalayas Essay

The Formation of the Himalayas

Introduction

The formation of the Himalayas is dated to have taken place during the Cenozoic era in the tertiary period. It is noted to be one of the youngest mountain ranges on planet earth. The formation of the Himalayas is as a result of a series of processes that led to the collision of Asia with India alongside the convergent plate boundary hence the Himalayas. The Himalayas was formed due to strong movements by the earth that affected the indo- Australian plate and the Eurasian plate. There was a line in the beginning of the continental collision during the early cretaceous period that led to the separation of the indo- Australian plate and the Eurasian plate. Consequently, the movement of the two plates led to the development of the Himalayan range. The movements made by the earth facilitated for the rise of the deposits that had been laid in the superficial Tethys Sea. The Tethys Sea is the current location of the Himalayas Mountains. The Himalayas has continued to undergo constant changes and developments as a result of the occurrence of earthquakes (Singh, 2009).

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The Formation of the Himalayas

The Himalayas are generally known to be the young fold mountains. Although they formed many millions of years ago, they are relatively new compared to other mountains such as the Appalachian in the United States and the Aravallis in India. They are also referred to as the Fold Mountains owing to the fact that they extend for about two thousand five hundred kilometers in length in series of parallel folds or ridges (Robinson, 2008). The Himalayas are also comprised of four distinctive ranges i.e. the Trans Himalayas found in the north, the Tibetian or Greater Himalayas, the Lower or Lesser Himalayas and the Outer Himalayas which is found in the southern most part of the mountain. Each of the ranges in the Himalayas is distinct due to the reason that they have diverse geological histories. The histories are based on issues such as the geologic time and place where the great plates that make up the crust of the earth collided and when and where the ranges were elevated (Science Jrank, 2009).

The formation of the Himalayan Mountains has been attributed to varied movements including block movements as well as the formation of the Alpine Himalayan Tethyan geosynclines and the convergence of the Eurasian and Indian plates. The block movements consider the role of horizontal translations on low angle thrusts. The geosyncline’s model on the other hand is of the point of view that the Himalayas were formed due to geosynclines that represent reactivated regions of the Indian shield (Robinson, 2008).

The formation of the Himalayas Mountains is associated with the theory of Continental Drift that was developed by Alfred Wegener. However, there are several theories that have been geologically accepted to illustrate the formation of the Himalayas. The Continental drift theory points out that the earth is made up of a number of giant plates known as the tectonic plates. According to a number of accepted geological theories, there was once an island continent that was known as the Gondwanaland which India was part of. Gondwanaland was separated by the primordial Tethyan Ocean from the Eurasian continent. The mountains were affected by erosion forces and the residues of the erosion process were set down in the Tethyan Ocean. The movement of India towards the north begun about one hundred and forty million years ago and this resulted to its collision with the Eurasian continent (Sussman & Weil, 2004).

The first step to the formation of the Himalayas is the occurrence of a collision between Gondwana plate and the Angara plate. The collision resulted to the rise of the seabed to form longitudinal valleys and ridges. In about two hundred and fifty million years ago, the land on earth was made up of one large continent referred to as the Pangea. Pangea was surrounded by a large ocean. However, there was an extensive stretch of the sea along the longitudinal area approximately fifty million years later. Around the Middle Permian Period, the Pangea begun to split away into varied land masses. The split of the super continent or Pangea occurred in different directions and an extensive part of the Tethys Sea was stretched along the longitudinal area. It is the longitudinal area that is being currently occupied by the Himalayas. The extensive sea was the Tethys and the Pangea gradually drifting away to form the various land masses since the splitting plates moved in different directions (Robinson, 2008).

The split of the Pangea contributed to the occurrence of erosion and weathering activities. This is due to the reason that after the split, rivers were able to transport large quantities of sediments that would be deposited to the shallow Tethys Sea. The rivers that were from the Angara or the northern Eurasian land mass as well as those from Gondwanaland or the southern Indian land mass began to deposit large quantities of sediments into the shallow sea of Tethys. During this time, there were some marine animals known as the ammonites living in the sea. The Eurasian and the Indian plates continued to move closer and closer to each other at a rate of about fifteen centimeters in a year or six inches in a year (Singh, 2009).

The Indian plate pushed towards the Eurasian plate in a relentless manner in that it caused the Tethys Trench to be compressed, to get folded and faulted. Beneath the trench, there were weak sedimentary rocks. The colliding of the two plates caused the sedimentary rocks to break hence allowing the granite and the basalt to infringe upward from the underlying mantle of the earth. The new materials were both hard and fresh. The encounter by the Tethys trench and the Indian plate led to the plate being sheared under or in other words, the plate was subducted under the trench. The trench however was forced to rise up or elevate because the subducted plate and compressive forces were pushing it leading to the water draining away. By and large, the Tethys Sea was completely locked by the Indo Australian plate due to the occurrence of geological process such as erosion and weathering resulting to the formation of sediments. The sediments did not sink as they should but rather rose upwards leading to the formation of the Himalaya (Science Jrank, 2009).

On the other hand, the water was drained away by the elevation of the Tethys range causing the bed of the ocean to be flat. The flat bottom of the ocean is what has become the present day Tibetian Plateau. The southern part of the Plateau was formed by the Trans Himalayan range. With the formation of mountains and the creation of rivers, the drainage of these features caused changes to the climate and the down-slope landscape. During the formation of the Himalayas, there were no much monumental elevations as observed presently (Science Jrank, 2009).

The Tethys bed rose to a large extent hence causing the sea to finally retreat. The plates had affected the already shallow seabed hence it had rapidly folded and raised to form longitudinal valleys and ridges. About seventy million years ago or the Upper Cretaceous Period, the colliding of the plates begun and because the Tethys Sea was already shallow, the seabed folded rapidly.  It is during the second phase of mountain building, that is the Upper Eocene Period, that the sea bed of Tethys started to rise again. The rise caused the sea to retreat while the sea bed was elevated into forming high mountain ranges. The retreat of the sea caused the sea bed to rise again hence the high mountain ranges were formed. The retreat led to the formation of the Tibetian Himalayas and the Great Himalayas (Bisht, 2008).

The rate of subduction slowed down from around fifty to twenty five million years ago due to the reason that the Indian plate was too jaunty to be drawn into the mantle. This led to the corner of the plate intersecting with Asia and beginning to slide beneath Asia. Conversely, it is during the Middle Miocene Period that there was intensification of the compression of plates hence the formation of the Himalayas preceded to the Pliocene Period. With the continuous slide of the Indian plate under the Asian plate, the upper layers of the Indian plate were stripped off and also arched back on the subcontinent. The layers were older ancient metamorphic rocks that came from the ancient Gondwanaland. With the rise in the elevation of mountains, rivers continued to be steep and there was increased in runoff as well as erosion. Similarly, the quantity of sediments being deposited also increased and in turn, the mass of the sediments caused the receiving basins to sink further so that they could be able to hold more alluvium steadily (Science Jrank, 2009).

The effect of the collision of the two plates as well as the contraction of the Tethys Sea is that the rocks in the northern India, those on the ocean crust, and the deep residues from the sea of the Cretaceous and Jurassic ages joined together and contributed to the formation of the Himalayas. Therefore, the rocks in the region were influenced by the events of that time and those events facilitated for movements that influenced the formation of rocks (Singh, 2009). The mechanics beneath the surface of the earth explain the collision of the two plates. The plates beneath the surface of the earth together with recession and sliding of these plates led to the rising of the Himalayas. Beneath the surface of the earth, the collision action of the plates results to generation of heat. The convection process that culminates forces hot currents to move upwards due to their lower. For that reason, the movement of the Indian plate towards the Indian plate makes the region of Himalayas not only very active but also prone to earthquakes as well. Therefore, any movement made by the Indian plate causes changes to the structure of the Himalayas (Balasubrahmanyan, 2006).

The lower Himalayas were later formed about twenty five million years ago. The other mountain building period (the Middle Miocene Period) resulted to the formation of the low Shivaliks ranges. The Himalayas continued to rise with the presence of erosion and this led to the formation of an adjoining lower range of hills (the Shivaliks). The Himalayas experienced thrusting from the erosive material hence it is the sediments that contributed to the formation of the low Shivaliks ranges. This means that as the Himalayas continued to rise as a result of the forces of the uplift, the rate of erosion was also high. This led to the formation of the contiguous lower hill ranges called the Shivaliks. The Shivaliks are made up of materials from erosion processes that result from rising Himalayas.The thrust of the Himalayas increases the quantity of sediments deposited in the ranges. Furthermore, it allows for the deposition of other materials in the ranges for instance fossils whose evidence indicates that they are proportional to the youth of the Himalayas. The mountain building phases were facilitated for by the reason that the Indian plate pushed against the Eurasian plate whereby it led to the Himalayan ranges rising further (Sati & Kumar, 2004).

There was a further uplift of the central axis especially during the second period of the upheaval. Elevation of the Himalayas ranges then took place thus the rise of the sub Himalayas. During the uplift, the current eminences of features such as the Nanda and the Garhwal Himalaya were attained. More so, during this period, there were intrusions of juvenile granites referred to as the leucogranites. The granites had a whitish color and the occurrence of the intrusions happened in the highest peaks such as the Shivling and the Bhagirathi sisters (Bisht, 2008).

The collision of Asia and India as well as the contraction of the Tethyan Ocean contributed to the formation of the Himalayas. This process started millions of years ago when the two plates or land masses started to collide with each other. The rocks in the region, mountains in the northern part of India, the oceanic crust, the deep residues of the cretaceous and Jurassic ages also contributed to the formation of the Himalayas. After the Middle Miocene Period, there was the occurrence of mountain building phases whereby the Indian plate pushed against the Eurasian plate which resulted to the Himalayan ranges rising further (Carey, 1988).

The movement of the continental drift resulted to the collision of Asia and India hence various plates collided, diverged and did slide from one another at approximately 2 centimeters per year. The activities that occurred beneath the surface of the earth are what led to the rise of the Himalayas by an estimated five millimeters per annum. The place where the two continents joined is known as the Indus Yarlung Suture zone. Although India is still moving northwards, the movement is slower at about 2 centimeters per year. According to the geological theory developed in the recent past, the forces that cause movement, faulting and deformation to the earths crust are such that the indo Australian plate that is north bound was making movements of about fifteen centimeters per year during the time of the collision (Bisht, 2008).

The collision of the two plates is a process that took place in some distinctive stages of tectonic changes. Processes such as sedimentations, magma formation, deformation and metamorphic process are associated with the “late Mesozoic subduction of the Neo Tethys oceanic lithosphere; accretion along Shyok Suture Zone and Indus Tsangpo Suture Zone in the north”. This process happened in the Trans Himalayan Zone. The next stage is the resulting Tethyan, Lesser and Higher Himalayan zones accruing from Cenozoic collision tectonics. The late Collision extensional tectonics is the other stage of the collision process of the two plates. This is where sediments accruing from collision related Quaternary and Cenozoic foreland extended into the Indo Ganga plains and also the Arabian Sea’s mega-fans and the Bay of Bengal. After the collision process, sedimentation in fore deeps led to the burial of the terrain of the Himalayas and the post-ceding extensional tectonics (Balasubrahmanya, 2006, p.151).

There are several lifts that the Himalayas went through before the formation of the present mountains. In the first uplift, the Trans Himalaya was formed. At the southern part of the Trans Himalaya, there is a high Himalayan area where the range attains its highest point. In this region, there is the old crystalline rock which is the oldest material of the core in the whole of the Himalayas. It is pointed out that it is approximately two billion years old. The sediments from the Tethyan have been compacted hence forming the core of the Himalayas. This was the main central thrust. According to Carey (1988, p.249), the Main Central Thrust is “where the pre- Himalayan basement first turns up to reappear at the surface, and is carried forward as a great nappe”. A large part of the erosive material is already eroded and the remnants are referred to as the klippe.

The effect of the last up thrust of the Himalayas had a lot of effects not only on the Himalayas but to other regions near the Himalayas as well. The Karakorum, the Trans Himalaya and the whole area of Tibet were affected by the formation process of the Himalayas because a large part of the region had been uplifted. In addition, the ice age was affected because the glaciers retreated and as a result, the Himalayas lakes were formed. The glacial remnants of the formation process of the Himalayas are indicated by the presence of Chandratal and Pangong. Apart from the glacial remnants, large lakes were also formed since the emerging ranges of the Himalayas blocked the flow of rivers. For example, the rise of the Pir panjal led to the blockage of the Jhelum and in turn it turned The Vale of Kashmir into a lake (Bisht, 2008).

Although the phase of the most important upheaval of the Himalayas has already taken place, the Himalayas are noted to be continuously rising. However, the rising rate of the Himalayas is rather slow compared to the rate at which it rose during its prior processes of formation. The Indian plate for instance is moving towards the north at an estimated rate of two centimeters each year. For that reason, the Himalayas are rising at an estimated rate of five millimeters per year. This indicates that although the Himalayas have been formed, they are still unstable in terms of structure and are geologically active. There is frequent incidence of earthquakes in the whole region of the Himalayas (Carey, 1988).

Currently, it is supposed that the Indo Australian plate is moving at a rate of sixty seven millimeters per year. According to projections, it is asserted that there is a possibility that the plate would have made movements of about one thousand five hundred kilometers into Asia in the coming ten million years. Conversely, this does not mean that the projections that have been made on the movement of plates as well as the uplifting of the Himalayas have been easily made but the use of technologies such as the Global Positioning System or the GPS have made it possible to undertake such activities (Sussman & Weil, 2004).

Conclusion

The formation of the Himalayas is one of the most recent mountains building activities compared to a number of other mountains in the world. The formation of Himalayas began with the acceptance of the Continental Drift Theory which articulated that the earth was once one super continent called Pangea but split and formed various continents on the earth’s surface today. One of the effects of this shift is the shift of the Indian plate towards the Eurasian plate leading to a collision that culminated to the formation of the Himalayas. The Tethys Sea used to occupy an extensive stretch but the collision of the two plates resulted to its displacement because the elevation of the Himalayas occurred in the latitudinal area where the Tethys Sea used to occupy. For millions of years, the Himalayas have experienced upheavals but its rise is still in progress although the rate of elevation is slower than it was in the past. Generally, Himalayas is not fully formed hence it is still geologically active and structurally unstable.

References

Balasubrahmanyan, M. N. (2006). Geology and Tectonics of India: An Overview. Durham: Balasubrahmanyan Publication.

Bisht, R. C. (2008). International Encyclopedia of Himalayas Vol. 5. Delphi: Mittal Publications

Carey, S. W. (1988). Theories of the Earth and Universe: a History of Dogma in the Earth Sciences. Stanford: Stanford University Press

Robinson, D. M. (2008). Forward Modeling the Kinematics Sequence of the Central Himalayan Thrust Belt, Western Nepal. Journal Geosphere. Vol. 4 (5), pp.785-801

Sati, V. P & Kumar, K. (2004). Uttaranchal: Dilemma of Plenties and Scarcities. Delphi: Mittal Publications

Science Jrank (2009). Geology of Himalayas: Ranges and Origin, Mountain Building, Seismic Activity. Retrieved June 14, 2009, from,

            http://science.jrank.org/pages/3338/Himalayas-Geology.html

Singh, K. (May 21, 2009). A Biography of the Himalaya. Retrieved, June 14, 2009, from

            http://www.geocities.com

Sussman, A. J. & Weil, A. B. (2004). Orogenic Curvature: Integrating Paleomagnetic and Structural Analysis. New York: Geological Society of America