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BGYET-147: Geomorphology and Geotectonics

BGYET-147: Geomorphology and Geotectonics

IGNOU Solved Assignment Solution for 2023

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Assignment Code: BGYET-147/TMA/2023

Course Code: BGYET-147

Assignment Name: Geomorphology and Geotectonics

Year: 2022-2023

Verification Status: Verified by Professor


Part A


Q1) Write short notes on the following:


a) Endogenic geomorphic processes

Ans) Endogenic processes are those that take place within the crust, mantle, and core of the earth. Endogenic processes are responsible for the development of the earth's surface through the use of geological processes. Endogenic processes are those that start from inside the earth and are powered by energy that is derived from the earth's core. These processes are also known as geothermally driven processes.


Endogenic geomorphic processes are the names given to the natural processes that are responsible for the development of the surface of the earth. Plate tectonics, volcanism, and earthquakes are all examples of these types of processes. Plate tectonics is the study of the movement and collision of large portions of the earth's crust and is referred to as "tectonic plates." This process is responsible for the formation of mountains as well as the trenches that may be found in oceans.


Volcanism, which can be defined as the process by which molten rock is ejected from the earth's mantle, is the process that is responsible for the construction of new landforms such as mountains, islands, and volcanic plateaus. Vibrations are caused as tectonic plates move past one another, which can lead to the formation of faults, ridges, and other landforms. This movement of the plates is what generates earthquakes. Earthquakes are one potential origin for these tremors.


Both the development of natural resources like oil, gas, and minerals, as well as the formation of the surface of the Earth, are inextricably linked to these endogenous processes, which play an incredibly significant role in both of these processes. Earthquakes, volcanic eruptions, and tsunamis are all examples of natural disasters that have the potential to exert a significant influence on human society and to pose serious risks. These natural disasters are also capable of having a substantial influence on the health of human beings.


b) Relationship of climate with landform development

Ans) The climate played a crucial role in the development of the landforms that we see today. The climate has a substantial influence on a variety of geological processes, including weathering, erosion, and deposition. These processes are ongoing and take place throughout the course of time. The combination of varied climatic conditions, geologic materials, and topographic features leads to the production of a wide variety of landforms on Earth. These landforms can be distinguished by their distinctive appearance and function.


Because wind erosion and weathering processes are the predominate geological forces in these locations, desert landscapes such as sand dunes, rock pedestals, and mesas are developed when rainfall is scarce in areas that are arid. The processes of water erosion and deposition are responsible for the production of a wide variety of different types of landforms, and these locations are responsible for the formation of these landforms because they receive a lot of rainfall. River valleys, waterfalls, and deltas are all examples of these types of landforms.


In addition, climate has a part in the formation of glaciers, which, in turn, can alter the topography by creating fjords, valleys in the shape of a U, and deep valleys. Waves and storms have a huge influence on the coastline, helping to shape it and giving rise to a variety of landforms such as cliffs, beaches, and barrier islands along the way. The climate is another important factor that plays a part in the development of coastal regions.


Q2) Give an account of the development of geomorphological concepts.

Ans) Ancient civilizations were the first to notice and record geological occurrences, such as earthquakes and volcanic eruptions, which led to the creation of geomorphological notions. These early civilizations may be traced back to the ancient ages. However, the study of geomorphology did not start to become its own independent branch of research until the 19th century. William Morris Davis, an early pioneer in the field of geomorphology, is credited with developing the idea of geomorphic cycles in the late 19th century. Davis was one of the first pioneers in the field. He hypothesised that landforms go through cycles of erosion and deposition, which, when repeated over long periods of time, give rise to a variety of unique landforms. Davis also established the idea of a landscape's "graded profile," which he believed indicated a balance between uplift and erosion. He called this concept the "graded profile of a landscape."


A new school of thought emerged at the beginning of the 20th century, and it was led by the German geographer Richard Hartmann. Hartmann was the one who proposed the idea of "dynamic equilibrium" in landscapes. Hartmann felt that landscapes were always shifting, but that the general contours and structure of the land maintained in a state of equilibrium despite these shifts. Around the middle of the 20th century, scientists were able to conduct more in-depth analyses of landscapes and landforms because to novel methods such as radiocarbon dating and aerial photography. This led to the development of the idea of "process geomorphology," which places an emphasis on the study of the processes that shape the landscape, such as weathering, erosion, and deposition. Process geomorphology was established as a result of this.


The idea of plate tectonics, which was established in the 1960s and 1970s, completely changed the way that the study of geomorphology was conducted. The theory of plate tectonics was developed to explain the motion of the Earth's crust, the genesis of mountains, and the location of earthquakes and volcanoes. Studies of landscapes and landforms are able to become increasingly in-depth and precise because to recent technological advancements, such as satellite photography and computer modelling, which are contributing to the ongoing development of geomorphology as a subject of study in the modern day. In addition, the study of geomorphology has become increasingly interdisciplinary, with academics from a wide range of subjects, such as geology, geography, and environmental science, working together to develop a deeper comprehension of the processes that create the surface of the Earth.


Q3) Describe River profile and grading of a river.

Ans) The view of a river as it is cut through the landscape that it flows through is referred to as a river profile. It is a representation of the rise in elevation that the riverbed experiences from its beginnings to its end. The river profile illustrates the ways in which the river shifts in slope and width as it runs downstream, as well as the ways in which it engages with the landscape in its immediate environment. There are three primary sections that make up the profile of the river, and they are the upper channel, the middle course, and the lower course. The upper course of the river is distinguished by the presence of steep gradients, strong flow rates, and a channel that is rather small. The river's middle course is distinguished by a gradient that is not as steep, a speed that is not as fast, and a channel that is not as narrow. The river's lower course is characterised by a very gentle gradient, sluggish velocity, and a wide channel. The river also widens as it travels downstream.


The alteration in the profile of a river over the course of time is referred to as the process of river grading. Whenever there is a shift in discharge, sediment supply, or base level, the river's grade will shift as well. When grading a river, the objective is to establish a channel form that is stable and able to move water and material without causing an excessive amount of either erosion or deposition. Erosion is the primary agent of river grading in the section of the river that is located upstream from the mouth of the river. The river carves a valley in the shape of a V into the rocks as it flows downstream. The most significant amount of river grading activity takes place in the river's middle course. The river winds its way through the landscape, eventually producing a valley in the shape of a U. This part of the river is characterised by both erosion and deposition, which ultimately results in the development of meanders, oxbow lakes, and floodplains. The river's lower course has a fairly mild gradient, and it carries a significant amount of silt despite the river's overall lack of steepness. Deposition is the primary factor in determining how the river grades. A delta or an alluvial fan may be formed as a result of the deposition of silt by the river.


River grading is not a linear process, and the river profile can shift over time as a result of shifts in discharge, sediment supply, and base level. The river profile and grade can also be significantly altered by human activities such as the construction of dams, channelization, and urbanisation, which all have the potential to have a substantial impact.


Q4) Explain geomorphic divisions of India.

Ans) The landforms of India are the result of a wide range of geomorphic processes that have been operating over the course of millions of years. India is a geologically diverse country. The various topography of India can be organised using a system called geomorphic divisions, which is based on the predominate landforms found there as well as the country's geologic history. The Northern Mountains, the Northern Plains, the Peninsular Plateau, the Indian Desert, and the Coastal Plains are the six primary geomorphic divisions that make up India. The Islands make up the sixth major geomorphic division.


  1. The Northern Mountains: This division is in the northern part of India and includes the Himalayas, the Karakoram Range, and the Hindu Kush Range. These mountains were formed because of the collision between the Indian and Eurasian tectonic plates, and they contain some of the world's highest peaks, including Mount Everest and K2.

  2. The Northern Plains: This division is located south of the Himalayas and includes the fertile Ganges and Indus River plains. These planes were formed by the deposition of sediment carried down from the Himalayas by the Ganges and Indus rivers.

  3. The Peninsular Plateau: This division covers most of the central and southern part of India and includes the Deccan Plateau and the Chota Nagpur Plateau. The Peninsular Plateau was formed by volcanic activity and the folding of the Earth's crust. It is characterized by hills, plateaus, and basins, and is rich in mineral resources.

  4. The Indian Desert: This division is in western India and includes the Thar Desert. The Indian Desert was formed by the erosion of the Aravalli Range and the deposition of sediment by the Indus River.

  5. The Coastal Plains: This division includes the narrow coastal plains along India's east and west coasts. These planes were formed by the deposition of sediment carried by the rivers that flow into the Bay of Bengal and the Arabian Sea.

  6. The Islands: This division includes the Andaman and Nicobar Islands in the Bay of Bengal and the Lakshadweep Islands in the Arabian Sea. These islands were formed by volcanic activity and coral reefs.


The geomorphic divisions of India offer a framework that can be utilised in order to gain an understanding of the varied topography and geologic history of the country. In addition to this, they are a significant factor in determining the climate, vegetation, and patterns of human habitation across the country.


Q5) Describe various types of glacial depositional landforms and their formation.

Ans) Glaciers are extremely powerful agents of both erosion and deposition, and over the course of thousands of years, they transform the landscape. When glaciers move down valleys and over landscapes, they transport and deposit sediments, which results in the formation of landforms known as glacial deposition landforms.

There are many different kinds of glacial depositional landforms, and each one has its own particular traits and procedures that led to its formation.


  1. Moraines: Moraines are ridges of glacial till that form along the edges and down the middle of glaciers. They are composed of unsorted rock and sediment that has been eroded and transported by the glacier. Lateral moraines form along the sides of glaciers, while medial moraines form in the middle where two glaciers converge.

  2. Drumlin: A drumlin is a hill that is smooth and long and is made of glacial till. It is streamlined in the direction that glaciers flow, hence it is called a drumlin. They are almost often seen in groups and can be as long as a few kilometres at their longest point.

  3. Esker: Eskers are long, curving ridges made of gravel and sand that occur in the bed of a subglacial stream. Eskers can be found in places where glaciers have retreated. They come into existence as a result of deposits made by meltwater as it travels through tunnels beneath the glacier.

  4. Kame and Kame Terrace: Kames are small, conical hills of sand and gravel that form when sediment accumulates in depressions in the ice surface. Kame terraces are long, low ridges of sediment that form along the edge of a receding glacier.

  5. Outwash Plain: When meltwater drains away from a glacier, it leaves behind a broad, flat region composed of sand and gravel known as an outwash plain. This area forms in front of the glacier. Sand dunes and streams that are braided together define their landscape.

  6. Glacial Erratics: Glacial Erratics are large boulders that have been transported by glaciers and deposited in a new location. They are often made of rock types that are not found in the surrounding area and can be used to trace the path of the glacier that transported them.


The glacial erosion, transportation, and deposition processes all worked together to generate these glacial depositional landforms. The precise method of development is determined by the type of landform, the characteristics of the sediment, and the activity level of the glacier.


Part B


Q6) Discuss Wegener's Continental Drift Hypothesis. Add a note on the evidence favouring the concept.

Ans) The idea that all of the continents were originally united together in a single supercontinent known as Pangaea and then progressively drifted apart over the course of millions of years is known as Wegener's Continental Drift Hypothesis. The hypothesis proposed that the continents drifted slowly over the surface of the Earth, and that the movement took place as a result of forces originating from within the interior of the Earth. Alfred Wegener is credited as being the first person to give thorough data in support of the notion in 1912, despite the fact that the concept was articulated as early as the 16th century.


The startling similarities in the geology and rock formations of the continents, which appeared to fit together like pieces of a jigsaw puzzle, was the most important piece of evidence that backed the theory. For instance, the Appalachian Mountains in North America, the mountains in Scotland and Norway, and the mountains in eastern Greenland all possessed comparable types of rock and were thought to have formed at around the same time geologically. In a similar vein, the discovery of fossils of particular plants and animals on continents that are currently separated by large oceans is evidence that these continents were previously joined together.


The extraordinary similarity of climate evidence between continents that are separated by seas was another observation that Wegener made. Some examples of this striking similarity were coal deposits found in Antarctica and glacial deposits found in Africa and South America. As a result of his findings, he came to the conclusion that the continents must have at one time been connected but have since gradually become disconnected.


However, the scientific community initially viewed Wegener's concept with mistrust due to its seemingly contradictory predictions. One of the most important arguments against it was that there was no known mechanism that could explain the movement of continents. The notion put forward by Wegener wasn't given additional support until the 1960s, when new evidence began to surface. This data was uncovered as a result of the discovery of mid-ocean ridges, oceanic trenches, and the process of plate tectonics, which explained the movement of continents and gave a cause for their movement.


The ground-breaking theory known as Wegener's Continental Drift Hypothesis postulated that the continents were originally joined together but have since drifted apart over the course of millions and millions of years. New data from plate tectonics and geological observations have since validated the hypothesis, and it is now largely recognised within the scientific community. Initially, the theory was regarded with scepticism; but, since then, it has been supported by several lines of evidence.


Q7) Write short notes on the following:


a) Mechanism of seafloor spreading

Ans) The process by which new oceanic crust is formed at the mid-ocean ridges and subsequently spreads outwards, forcing the older crust away from the ridge, is known as the mechanism of seafloor spreading. This process, known as seafloor migration, refers to the movement of the existing crust away from the ridge. The movement of the tectonic plates that are located in the crust of the earth is what causes this process to take place.


At the mid-ocean ridges, magma rises up from the mantle and, as it cools, it solidifies to build new crust on the ocean floor. This process occurs repeatedly. After then, the newly formed crust is pulled away from the ridge by the force of convection currents in the mantle, which ultimately causes it to move further away from the ridge. As the crust moves farther away from the ridge, it experiences a loss of heat and becomes thicker. Eventually, it will sink back down into the mantle at the oceanic trenches, where it first emerged from the mantle.


The theory of plate tectonics is an effort to explain the movement of the Earth's crust by including the process of the spreading of the seafloor as an integral component of the explanation. The process of seafloor spreading has been observed and studied using a variety of methods, such as the mapping of the seafloor using sonar and the measuring of magnetic anomalies in the marine crust. These are just two examples of the many methods that have been used. Both of these approaches are instances of different strategies that have been applied in the past.


b) Types of rock magnetism

Ans) The term "rock magnetism" refers to the magnetic qualities that rocks and the minerals that make them up possess. There are several distinct varieties of rock magnetism, including the following:


  1. Remanent Magnetization: This term refers to the magnetism of a rock that persists after the rock has been exposed to a magnetic field. Natural and induced magnetization are the two categories that make up remanent magnetization.

  2. Anhysteretic Remanent Magnetization (ARM): This is a specific kind of remanent magnetization that can be obtained by a rock when it is exposed to a magnetic field that first grows in intensity and then gradually fades away until it reaches zero.

  3. Isothermal Remanent Magnetization (IRM): This is a specific sort of remanent magnetization that can be obtained by a rock when it is exposed to a magnetic field whose intensity is maintained over time.

  4. Thermal Remanent Magnetization (TRM): This is a term that refers to the magnetism that is obtained by a rock when it is heated to a certain temperature in the presence of a magnetic field and subsequently cooled. This process is known as a ferro magnetization.

  5. Magnetic Susceptibility: In the presence of a magnetic field, this refers to the extent to which a rock or mineral can become magnetised.


Q8) With the help of suitable diagrams, explain geological processes operating at convergent and divergent plate boundaries.

Ans) Geological processes operating at convergent and divergent plate boundaries:


Convergent Plate Boundaries

The formation of convergent plate borders results from the movement of two tectonic plates in the same direction toward one another. There are three different kinds of convergent plate boundaries: oceanic-oceanic, oceanic-continental, and continental-continental. Oceanic-continental convergent plate boundaries are the most common. The following is a list of the geological processes that are taking place at convergent plate boundaries:


  1. Oceanic-Oceanic Convergence: When two oceanic plates converge, one plate subducts beneath the other, forming a deep ocean trench. The subducting plate is heated and dehydrated, which triggers melting of the mantle wedge, leading to the formation of magma. This magma rises to the surface, forming a chain of volcanic islands called an island arc.

  2. Oceanic-Continental Convergence: As a result of a collision between an oceanic plate and a continental plate, a subduction zone is formed as the more dense oceanic plate is forced to subduct beneath the lighter continental plate. This process has the potential to result in the construction of a mountain range, an arc of volcanic activity, and even earthquakes.

  3. Continental-Continental Convergence: The collision of two continental plates results in the folding and thickening of the plates, which in turn leads to the creation of a mountain range. The rock may undergo severe folding, faulting, and metamorphism as a direct consequence of this process.


Convergent Plate Boundaries

Divergent Plate Boundaries

Divergent plate boundaries occur when two tectonic plates move away from each other. The geological processes operating at divergent plate boundaries are as follows:


  1. Mid-Ocean Ridges: At mid-ocean ridges, magma rises from the mantle and solidifies, forming new oceanic crust. As the plates move away from each other, the new crust is pushed aside, forming a ridge.

  2. Rift Valleys: When a divergent boundary occurs within a continent, it can lead to the formation of a rift valley. As the plates move apart, the continental crust is stretched and thinned, leading to the formation of a valley.

Divergent Plate Boundaries


Q9) Discuss in detail the main tectonic features of peninsular India.

Ans) Peninsular India is a region located in the southern part of India and is bounded by the Arabian Sea to the west, the Bay of Bengal to the east, and the Indian Ocean to the south. It is characterized by a diverse set of tectonic features that have developed over millions of years due to the complex geological history of the region.

The peninsular region is composed of several tectonic units, including the Archean Dharwar Craton, the Proterozoic Cuddapah Basin, the Proterozoic Vindhyan Basin, and the Gondwana sequence. The Archean Dharwar Craton is the oldest and most stable part of the region, dating back to around 3.4 billion years ago. The craton is made up of ancient rocks such as gneisses, schists, and granites.


The Proterozoic Cuddapah Basin is located to the east of the Dharwar Craton and is characterized by sedimentary rocks such as limestone, shale, and sandstone. The Vindhyan Basin is located to the north of the Cuddapah Basin and is characterized by sedimentary rocks that date back to around 1 billion years ago. The Gondwana sequence is a group of sedimentary rocks that are younger and are located towards the north-east of the region.


The major tectonic features of the peninsular region include the Eastern and Western Ghats, the Narmada-Tapi grabens, and the Deccan Plateau. The Eastern Ghats run along the eastern coast of India, while the Western Ghats run parallel to the western coast. These mountain ranges are believed to have formed around 1.8 billion years ago because of the collision between the Indian and Australian plates. The Western Ghats are particularly important as they are a biodiversity hotspot and home to several endemic species of plants and animals.


The Narmada-Tapi grabens are located between the Aravalli Mountains and the Satpura Range and are characterized by a series of parallel faults and valleys. These grabens were formed because of the rifting of the Indian Plate from the African Plate around 150 million years ago.


The Deccan Plateau is located to the south of the Narmada-Tapi grabens and is a large volcanic plateau that covers an area of around 500,000 square kilometers. The plateau was formed around 65 million years ago because of a massive volcanic eruption that lasted for millions of years. The Deccan Traps, which are a series of basaltic lava flows, are the most prominent feature of the Deccan Plateau.


Q10) Write short notes on the following:


a) Evolution of Himalaya

Ans) The Himalayas are the world's tallest mountain range, spanning more than 2,400 kilometres across the northern portion of the Indian subcontinent. The collision that occurred between the Indian and Eurasian plates approximately 50 million years ago was the cause of the beginning of the evolution of the Himalayas.


The Indian Plate began to crumple and fold as it travelled northward towards the Eurasian Plate, which resulted in the construction of the Himalayan Mountain range. In addition, the collision between the two tectonic plates was responsible for the elevation of the Tibetan Plateau, which can be found to the north of the Himalayas.


Because tectonic activity is always occurring in the region, the Himalayas continue to develop and alter up to this day. The area is still prone to earthquakes, and the upliftment that has occurred in the past has caused the mountains to continue to rise. The Himalayas also play a significant part in the climate of the region, as they have a significant impact on the monsoon patterns that are responsible for the majority of South Asia's precipitation.


b) Triple junctions

Ans) The location at which three different tectonic plates collide is known as a triple junction. These junctions are important geological features because they represent regions of intense tectonic activity and are associated with a variety of geological processes, such as earthquakes, volcanic activity, and the formation of new crust. As a result, these junctions are areas of intense tectonic activity.


Triple junctions can be broken down into three primary categories: ridge-ridge-ridge, ridge-trench-trench, and trench-trench-trench. At a ridge-ridge-ridge triple junction, the three ridges that run along the middle of the ocean meet at a single place to create a Y-shaped junction. When magma rises to the surface and solidifies, it creates new oceanic lithosphere, which is connected with these junctions. This process is known as the production of new crust.


A mid-ocean ridge will run into a subduction zone at a location known as a ridge-trench-trench triple junction. This is because the subduction zone is where two tectonic plates are coming together. These junctions are linked to high levels of seismic activity and have been linked to the production of volcanic arcs, such as those found in South America's Andes Mountains.


At a place known as a trench-trench-trench triple junction, there is a meeting of three different subduction zones. These junctions are extremely uncommon and are linked to a variety of complicated geological processes, such as the development of transform faults and the emergence of oceanic plateaus.

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