IAS GEOLOGY2022 PAPER 1 FULL SOLUTION CIVIL SERVICE MAIN
CIVIL SERVICES (MAIN) EXAM.1011 GEOLOGY (PAPER—I) Maximum Marks : 250Time Allowed : Three Hours SECTION—A 1.Answer the following questions in about 150 words each : 10x5=50 (a) Explain 'convergent plate boundary' with suitable examples. Add a note about the characteristics of earthquakes at the convergent boundary. A convergent plate boundary is a type of tectonic boundary where two plates move towards each other and collide. This collision can result in the formation of mountain ranges, volcanic activity, and earthquakes. There are three types of convergent plate boundaries: oceanic-oceanic, oceanic-continental, and continental-continental. In an oceanic-oceanic convergent boundary, two oceanic plates collide. One plate will typically be older and denser, while the other is younger and less dense. The denser plate will subduct (dive) beneath the other plate, forming a deep trench. This subduction can result in the formation of volcanoes on the overriding plate, such as the Aleutian Islands in Alaska. In an oceanic-continental convergent boundary, an oceanic plate collides with a continental plate. The denser oceanic plate will subduct beneath the lighter continental plate, creating a trench and often causing earthquakes. The Andes Mountains in South America are an example of an oceanic-continental convergent boundary. In a continental-continental convergent boundary, two continental plates collide. Since neither plate is dense enough to subduct, the plates will buckle and uplift, forming mountains. The Himalayas in Asia were formed by the collision of the Indian and Eurasian plates. Earthquakes at convergent plate boundaries are often shallow and can be very destructive. This is because the plates are not only colliding but also moving and rubbing against each other, causing stress to build up over time. When the stress is released, it results in an earthquake. These earthquakes can be very large and have the potential to cause tsunamis, particularly in oceanic-continental convergent boundaries where subduction occurs. (b) What is the difference between Raster and Vector data? Describe their characteristics as well as their advantages and disadvantages. Raster and vector are two types of data models used in geographic information systems (GIS) and other computer-based mapping applications. Raster data represent geographic information as a grid of cells, where each cell contains a value representing a specific attribute. This data model is commonly used to represent continuous data, such as elevation, temperature, or precipitation. Each cell in the grid has a fixed size and shape, and the values of adjacent cells can be used to create a smooth representation of the underlying data. Vector data, on the other hand, represent geographic information as a set of points, lines, and polygons. Points represent specific locations on the earth's surface, lines represent linear features such as roads or rivers, and polygons represent areas such as land use or administrative boundaries. Vector data are typically used to represent discrete data, such as the location of cities, the boundaries of countries, or the extent of a forest. The characteristics, advantages, and disadvantages of raster and vector data are: Raster data: Characteristics: Raster data are continuous in nature and represented as a grid of cells. Each cell in the grid contains a single value representing a specific attribute. Advantages: Raster data can be easily processed using mathematical operations such as addition, subtraction, or multiplication. They can be used to create smooth visualizations of continuous data such as elevation or temperature. Raster data can be easily manipulated, re-sampled, or transformed. Disadvantages: Raster data can be memory-intensive and computationally expensive. They may result in pixelation or distortion at different scales, and they may not be as precise as vector data for discrete features such as point locations. Vector data: Characteristics: Vector data are discrete in nature and represented as points, lines, or polygons. Each feature in the dataset contains a set of attributes that describe its characteristics. Advantages: Vector data are more precise than raster data for discrete features such as point locations, and they can be used to create accurate maps of features such as roads, buildings, and administrative boundaries. They are efficient for storing and displaying data that has well-defined boundaries and shapes. Disadvantages: Vector data can be more difficult to process than raster data, particularly when analyzing large datasets. They may require more storage space than raster data due to the need to store information about the shape and location of each feature. In summary, both raster and vector data have their advantages and disadvantages, and the choice of which data model to use will depend on the specific needs of the application. Raster data are more suited to continuous data and smooth visualizations, while vector data are more suited to discrete data and precise representation of features. (c)Illustrate and describe any five types of drainage pattern and give an account of the factors that influence drainage pattern development. Drainage patterns are the network of streams and rivers that drain an area. The pattern of the drainage system is determined by the underlying geology and topography of the area. The following are five types of drainage patterns: Dendritic pattern: This is the most common drainage pattern, and it looks like the branches of a tree. It forms in areas with a uniform rock type and a relatively flat landscape. The main river or stream has many smaller tributaries that join it at acute angles. Radial pattern: A radial drainage pattern forms on a volcanic cone or dome-shaped mountain. In this pattern, the streams radiate outwards from a central high point, forming a fan-like shape. Rectangular pattern: This pattern is characterized by streams that flow in straight lines at right angles to each other, forming a grid-like pattern. It typically forms in areas with a flat, uniform topography and jointed rock. Trellis pattern: The trellis pattern forms in regions with alternating bands of resistant and weak rocks. The main river flows through the resistant rock, and tributaries join it at right angles from the weaker rock bands. This results in a pattern that resembles a garden trellis. Parallel pattern: A parallel drainage pattern forms in areas with steep slopes or parallel ridges. The streams flow parallel to each other down the slope or ridge, with smaller tributaries joining at acute angles. Several factors can influence the development of drainage patterns, including: Topography: The slope of the land determines the direction and velocity of the water flow, which can affect the formation of drainage patterns. Geological structure: The underlying rock type and structure influence the rate of erosion and the resistance of the rock to erosion, which can determine the direction and pattern of the streams. Climate: The amount and intensity of precipitation, as well as temperature and humidity, can affect the amount and rate of water flow, which can influence the formation of drainage patterns. Human activities: Human activities such as damming, channelization, and urbanization can alter the natural drainage patterns, resulting in changes in the direction and velocity of water flow. Time: Over time, erosion and changes in the landscape can alter the drainage patterns, resulting in new patterns of streams and rivers. (d)Explain through neat sketches what drag folds are, and how they can be used to determine major fold structure. Drag folds are a type of fold that form as a result of deformation during folding of rocks. They are formed when an incompetent layer of rock or a fault zone is dragged along with the competent layers during folding, resulting in a fold that has a "dragged" appearance. Drag folds can be used to determine the major fold structure in the following ways: They indicate the direction of folding: The direction of the drag folds is typically perpendicular to the direction of the fold axis. Therefore, the orientation of the drag folds can be used to determine the direction of folding. They reveal the presence of fault zones: Drag folds that are associated with fault zones can be used to locate the fault zone and determine its orientation. They indicate the amount of deformation: The degree of folding in the drag folds can be used to estimate the amount of deformation that has occurred in the rock. They can be used to determine the geometry of the fold: The shape and orientation of the drag folds can be used to determine the geometry of the fold. The following is an example of how drag folds can be used to determine major fold structure: In the diagram below, a horizontal layer of rock is folded, and an incompetent layer of rock is dragged along during the folding process. Drag Folds Diagram From the diagram, it can be observed that: The direction of the drag folds is perpendicular to the direction of the fold axis, which indicates that the direction of folding is from left to right. The drag folds are associated with a fault zone, which can be used to locate the fault zone and determine its orientation. The degree of folding in the drag folds can be used to estimate the amount of deformation that has occurred in the rock. The shape and orientation of the drag folds can be used to determine the geometry of the fold. Therefore, drag folds can provide valuable information about the major fold structure of rocks, and can be used to understand the deformation history of an area. (e) Describe the structures showing gap in stratigraphic sequence caused by erosion and non-depositions. Gaps in stratigraphic sequences can occur due to periods of non-deposition or erosion, which interrupt the continuous deposition of sedimentary rocks. The following are two common structures that can show gaps in the stratigraphic sequence: Unconformities: An unconformity is a surface that represents a gap in the geological record, typically caused by erosion or non-deposition. There are three types of unconformities: Angular unconformities: An angular unconformity is formed when younger, horizontally deposited sedimentary rocks overlie older, tilted or folded sedimentary rocks. The tilted or folded rocks have been eroded, creating a gap in the geological record. Nonconformities: A nonconformity is formed when sedimentary rocks overlie igneous or metamorphic rocks. The igneous or metamorphic rocks have been eroded, creating a gap in the geological record. Disconformities: A disconformity is formed when sedimentary rocks overlie older, parallel sedimentary rocks. There is a gap in the geological record between the two layers of sedimentary rocks, indicating a period of non-deposition or erosion. Paleosols: Paleosols are ancient soils that have been buried by subsequent sedimentary deposits. They can be used to identify gaps in the stratigraphic sequence because they represent periods of time when sedimentary deposition was interrupted by a period of soil formation. Paleosols are characterized by distinct features, such as soil horizons, root traces, and weathering features. They can be used to infer the duration of the period of non-deposition or erosion, as well as the climate and vegetation that existed during that time. In summary, unconformities and paleosols are structures that can show gaps in the stratigraphic sequence caused by erosion or non-deposition. They provide important information about the geological history of an area, including the duration of periods of non-deposition or erosion, the nature of the environment during those periods, and the sequence of geological events that occurred. 2. (a) Discuss in detail the notion of 'continental drift' and the theories of plate tectonics as they relate to palaeogeography. 20 The concept of continental drift suggests that the continents of the Earth have moved over time, changing their positions on the surface of the planet. This idea was first proposed by Alfred Wegener in 1912, who observed that the coastlines of South America and Africa appeared to fit together like puzzle pieces. He proposed that the two continents were once part of a larger landmass that he called Pangaea, which began to break apart around 200 million years ago and eventually formed the continents we see today. Wegener's theory of continental drift was initially met with skepticism, but subsequent research provided evidence to support the idea. One piece of evidence was the discovery of similar rock formations and fossils on opposite sides of the Atlantic Ocean, which suggested that the two continents were once connected. Another piece of evidence was the pattern of magnetic reversals in the Earth's crust, which suggested that the continents had moved over time. The theory of plate tectonics, which emerged in the 1960s, built upon Wegener's idea of continental drift. Plate tectonics suggests that the Earth's outer shell, or lithosphere, is divided into a series of rigid plates that move relative to each other. These plates interact at their boundaries, which can be either divergent, convergent, or transform. At divergent boundaries, the plates move apart and new crust is formed. At convergent boundaries, the plates collide and one plate is subducted beneath the other, often causing volcanoes and earthquakes. At transform boundaries, the plates slide past each other. The theory of plate tectonics has been supported by a variety of evidence, including the distribution of earthquakes and volcanoes, the magnetic striping of the ocean floor, and the ages of the rocks on either side of mid-ocean ridges. The theory has also helped to explain the formation of mountain ranges, the opening and closing of ocean basins, and the formation of sedimentary basins. In terms of palaeogeography, the theory of plate tectonics has had significant implications. By understanding the movement of continents and the opening and closing of ocean basins, scientists can reconstruct the past positions of the continents and the distribution of land and sea. This information can be used to understand the evolution of life on Earth, as well as to explore the distribution of natural resources such as oil and gas. The theory of plate tectonics has also helped to explain the formation of major features such as the Himalayan Mountains, the Rocky Mountains, and the Andes, as well as the origin of major landmasses such as Australia and Antarctica. (b) Explain the principles of aerial photography and how it is classified. 15 Aerial photography is the process of taking photographs of the Earth's surface from an elevated position, usually from an aircraft or a drone. Aerial photography is an important tool in geology, geography, cartography, environmental studies, and many other fields. Here are the principles of aerial photography: Ground coverage: The area covered by the aerial photograph is determined by the altitude of the aircraft, the focal length of the camera, and the size of the film format. Scale: The scale of the photograph is the ratio of the size of an object on the photograph to its actual size on the ground. The scale is determined by the altitude of the aircraft, the focal length of the camera, and the size of the film format. Overlap: Overlap is the amount of coverage of the same ground area in two adjacent photographs. There are two types of overlap: longitudinal and transverse. Stereoscopy: Stereoscopy is the technique of viewing two overlapping aerial photographs in order to create a three-dimensional image of the terrain. Aerial photographs can be classified into several categories, based on their type, scale, and orientation. Here are the main types of aerial photographs: Vertical photographs: These are photographs taken with the camera pointed straight down at the ground, with no tilt or oblique angle. Oblique photographs: These are photographs taken with the camera tilted at an angle, usually around 45 degrees, to the ground. High-oblique photographs: These are photographs taken with the camera tilted at an angle greater than 45 degrees to the ground, but not quite to the point of being fully vertical. Low-oblique photographs: These are photographs taken with the camera tilted at an angle less than 45 degrees to the ground, but not quite horizontal. Aerial photographs can also be classified by their scale, which is the ratio of the size of an object on the photograph to its actual size on the ground. The three main scales are small-scale, medium-scale, and large-scale. Small-scale aerial photographs cover a large area but show little detail, while large-scale aerial photographs cover a small area but show great detail. In summary, aerial photography is a useful tool in geology, geography, cartography, and other fields. The principles of aerial photography include ground coverage, scale, overlap, and stereoscopy. Aerial photographs can be classified into several categories, including vertical, oblique, high-oblique, and low-oblique photographs, and can also be classified by their scale. (c ) -Illustrate and describe the linear structures of deformed rocks. 15 Linear structures in deformed rocks are features that result from tectonic deformation and can provide clues to the nature and orientation of the forces that acted upon the rocks. Here are some examples of linear structures in deformed rocks: Folds: Folds are linear structures that form when rocks are subjected to compressional forces that cause them to bend or buckle. Folds can be classified into several types based on their shape, including anticlines (upward-arching folds), synclines (downward-arching folds), and monoclines (single-bend folds). Faults: Faults are linear structures that form when rocks are subjected to shearing forces that cause them to fracture and move relative to one another. Faults can be classified into several types based on the direction of movement, including normal faults (where the hanging wall moves down relative to the footwall), reverse faults (where the hanging wall moves up relative to the footwall), and strike-slip faults (where the movement is horizontal and parallel to the fault plane). Joints: Joints are linear structures that form when rocks are subjected to tensional forces that cause them to crack and break without any movement along the fracture. Joints are often found in parallel sets and can be used to infer the direction and magnitude of the tensional forces that caused them to form. Cleavage: Cleavage is a linear structure that forms when rocks are subjected to compressional forces that cause them to deform plastically and align their minerals in a preferred orientation. Cleavage planes are often parallel to one another and can be used to infer the direction and magnitude of the compressional forces that caused them to form. Lineations: Lineations are linear structures that result from the alignment of minerals or other features within a rock due to tectonic deformation. Lineations can be classified into several types based on their orientation and shape, including mineral lineations (aligned minerals), stretching lineations (elongated structures), and pressure shadows (areas of no deformation adjacent to a deformed zone). In summary, linear structures in deformed rocks are features that result from tectonic deformation and can provide important information about the nature and orientation of the forces that acted upon the rocks. Examples of linear structures include folds, faults, joints, cleavage, and lineations.
• 3. (a) -Describe the geomorphic landforms produced by structural, weathering, erosional and depositional processes. Give four examples of each process. 20 Geomorphology is the study of landforms and the processes that create them. There are four main processes that shape the Earth's surface: structural processes, weathering processes, erosional processes, and depositional processes. Each of these processes produces distinct landforms. Here are some examples of landforms produced by each process: Structural Processes: Structural processes refer to the deformation of the Earth's crust due to tectonic forces. Some examples of structural landforms are: Fold mountains, such as the Himalayas, Andes, or Rocky Mountains. Rift valleys, such as the East African Rift or the Rio Grande Rift. Fault scarps, such as the San Andreas Fault in California. Horst and graben structures, such as the Rhine Graben in Europe. Weathering Processes: Weathering processes refer to the breakdown of rocks and minerals at or near the Earth's surface due to physical or chemical processes. Some examples of weathering landforms are: Rock outcrops or tors, such as Ayers Rock in Australia or Half Dome in Yosemite National Park. Boulders or rock piles, such as the Moeraki Boulders in New Zealand. Karst topography, such as the limestone caves and sinkholes in the Yucatan Peninsula or the Carlsbad Caverns in New Mexico. Hoodoos or rock spires, such as those in Bryce Canyon National Park in Utah. Erosional Processes: Erosional processes refer to the removal and transport of sediment by wind, water, or ice. Some examples of erosional landforms are: Canyons, such as the Grand Canyon in Arizona or the Yangtze River Gorge in China. River deltas, such as the Nile Delta in Egypt or the Ganges-Brahmaputra Delta in Bangladesh. Glacial valleys, such as Yosemite Valley in California or fjords in Norway. Sea cliffs or sea stacks, such as those on the coast of Ireland or California. Depositional Processes: Depositional processes refer to the accumulation of sediment by wind, water, or ice. Some examples of depositional landforms are: Alluvial fans, such as the Bajada del Diablo in Argentina or the Death Valley Alluvial Fan in California. Sand dunes, such as those in the Sahara Desert or the Great Sand Dunes in Colorado. Moraines, such as those left by glaciers in Yosemite National Park or the Swiss Alps. Barrier islands, such as the Outer Banks in North Carolina or the Florida Keys. In summary, each of the four main processes that shape the Earth's surface produces distinct landforms. Structural processes produce landforms such as fold mountains and rift valleys, weathering processes produce landforms such as rock outcrops and karst topography, erosional processes produce landforms such as canyons and sea cliffs, and depositional processes produce landforms such as sand dunes and barrier islands. (b ) Illustrate the discontinuities in the Earth's interior and discuss the mechanical and compositional layering of the Earth. 15 The Earth's interior is divided into several discontinuous layers based on changes in the physical properties of the Earth's materials. These layers can be broadly classified into two categories: mechanical and compositional layers. Mechanical layers are defined by the physical properties of the Earth's materials, such as their density, pressure, and temperature. These layers are: Lithosphere: This is the outermost layer of the Earth, comprising the crust and the uppermost part of the mantle. It is brittle and rigid, and it is broken into several tectonic plates that move around the Earth's surface. Asthenosphere: This is a weak and ductile layer of the mantle that lies beneath the lithosphere. It is made up of partially molten rock that can flow slowly over long periods of time. Mesosphere: This is the lower part of the mantle, which is solid and more rigid than the asthenosphere. Outer core: This layer is made up of liquid iron and nickel, and it surrounds the solid inner core. Inner core: This is the deepest layer of the Earth, and it is solid due to the high pressure and temperature. Compositional layers are defined by the chemical composition of the Earth's materials. These layers are: Crust: This is the outermost compositional layer of the Earth, and it is divided into two types: oceanic and continental crust. The oceanic crust is denser and thinner than the continental crust. Mantle: This is the largest layer of the Earth, and it is made up of silicate rocks. It is divided into the upper mantle, the transition zone, and the lower mantle. Core: This layer is made up of iron and nickel, and it is divided into the outer core and the inner core. The discontinuities in the Earth's interior are the boundaries between these layers where there are sudden changes in the physical properties of the Earth's materials. These include: Mohorovicic Discontinuity (Moho): This is the boundary between the crust and the mantle, and it marks the change from solid rock to more ductile rock. Gutenberg Discontinuity: This is the boundary between the mantle and the core, and it marks the change from silicate rock to metallic iron and nickel. Lehmann Discontinuity: This is the boundary between the outer core and the inner core, and it marks the change from liquid to solid iron and nickel. In summary, the Earth's interior is divided into several layers based on both mechanical and compositional properties. These layers are separated by discontinuities that mark sudden changes in the physical properties of the Earth's materials. (c ) Illustrate the principles of stereographic projection. How are the 'pi' and 'beta' diagrams useful to analyze fold structure? 15 Stereographic projection is a powerful tool used in structural geology to represent three-dimensional features on a two-dimensional plane. It involves projecting a sphere representing the Earth's surface onto a plane, which is then used to plot the orientation of structural features such as folds, faults, and cleavage. The principles of stereographic projection involve placing a point (representing the center of the sphere) on a plane and then projecting lines radiating from this point onto the plane. The resulting diagram is known as a stereographic projection, and it can be used to represent the orientation of structural features such as bedding planes or fold axes. In stereographic projection, the plane onto which the sphere is projected is called the stereographic plane, and it is often represented by a circular diagram. The center of the circle represents the point on the Earth's surface that is being projected, while the circumference represents the horizon. One useful application of stereographic projection in structural geology is the use of 'pi' and 'beta' diagrams to analyze fold structure. A pi diagram is a stereographic projection of the axial plane of a fold, while a beta diagram is a stereographic projection of the hinge line of a fold. In a pi diagram, the orientation of the axial plane is represented by a great circle on the stereographic projection. This allows for the analysis of the orientation and distribution of folds in a particular area. In a beta diagram, the orientation of the hinge line is represented by a line on the stereographic projection. This allows for the analysis of the geometry and shape of the fold. By using pi and beta diagrams together, it is possible to analyze the geometry, orientation, and distribution of fold structures in a particular area. This information can be used to better understand the tectonic history and structural evolution of the area, which can be useful in a variety of geological applications, such as mineral exploration and hydrocarbon exploration. 4. (a) Illustrate the common brittle-ductile shear zone structures. Using the stress ellipsoid, deduce the mechanism of faults. 20 Brittle-ductile shear zones are geological features where rocks undergo both brittle and ductile deformation due to shear stress. They often occur in regions where rocks are subjected to tectonic stresses, such as along fault zones. The structures that form within these shear zones can provide insights into the deformation processes that occurred. There are several common structures that can form within brittle-ductile shear zones: Cataclasite: A cataclasite is a type of fault rock that forms from the crushing and grinding of rock fragments. It has a rough, angular texture and may contain fragments of various sizes. Mylonite: A mylonite is a type of rock that forms from the ductile deformation of rocks under high strain rates. It has a fine-grained, layered texture and may contain elongated mineral grains. Pseudotachylite: A pseudotachylite is a type of fault rock that forms from the frictional melting and rapid cooling of rocks during seismic events. It has a glassy texture and may contain fragments of various sizes. The formation of these structures can be explained using the stress ellipsoid, which is a graphical representation of the three principal stresses acting on a rock. The principal stresses are represented by the three axes of the ellipsoid, with the longest axis representing the maximum principal stress (σ1), the intermediate axis representing the intermediate principal stress (σ2), and the shortest axis representing the minimum principal stress (σ3). In a brittle-ductile shear zone, the deformation mechanism can be determined by examining the orientation of the stress ellipsoid. If the ellipsoid is elongated in the direction of the shear zone, then the deformation is dominated by ductile processes. This is because the maximum principal stress (σ1) is oriented perpendicular to the shear zone and the intermediate and minimum principal stresses (σ2 and σ3) are oriented parallel to the shear zone. If the ellipsoid is flattened in the direction of the shear zone, then the deformation is dominated by brittle processes. This is because the intermediate and minimum principal stresses (σ2 and σ3) are oriented perpendicular to the shear zone and the maximum principal stress (σ1) is oriented parallel to the shear zone. The orientation of the stress ellipsoid can also provide information about the type of faulting that occurred. For example, if the maximum principal stress (σ1) is oriented vertically and the intermediate principal stress (σ2) is oriented horizontally, then normal faulting is likely to have occurred. Conversely, if the maximum principal stress (σ1) is oriented horizontally and the intermediate principal stress (σ2) is oriented vertically, then reverse faulting is likely to have occurred. In summary, the structures that form within brittle-ductile shear zones can provide insights into the deformation processes that occurred, and the stress ellipsoid can be used to deduce the mechanism of faulting. (b ) Describe the various platforms and sensors used in Remote Sensing. 15 Remote sensing is the science of acquiring information about the earth's surface without being in direct physical contact with it. It involves the use of various platforms and sensors to capture, record and analyze data from the electromagnetic spectrum. Here are the various platforms and sensors used in remote sensing: Aerial Photography: Aerial photography involves capturing images of the earth's surface using cameras mounted on airplanes or helicopters. The images can be captured in black and white, color or infrared. Satellite Imaging: Satellite imaging involves capturing images of the earth's surface using cameras mounted on satellites orbiting the earth. The images can be captured in different spectral bands, including visible, near-infrared, shortwave infrared, thermal infrared and microwave. LiDAR: LiDAR (Light Detection and Ranging) is a remote sensing technology that uses lasers to measure distances between the sensor and the earth's surface. LiDAR sensors can be mounted on airplanes or helicopters, and they can capture highly accurate elevation data, as well as data on vegetation cover and other surface features. Radar: Radar (Radio Detection and Ranging) is a remote sensing technology that uses radio waves to measure distances and detect objects on the earth's surface. Radar sensors can be mounted on airplanes or satellites, and they can capture data on surface features, vegetation cover, and ocean currents, among other things. GPS: GPS (Global Positioning System) is a satellite-based navigation system that is used to determine the precise location of objects on the earth's surface. GPS is commonly used in conjunction with other remote sensing technologies to accurately georeference and map data. Drones: Drones, or unmanned aerial vehicles (UAVs), are becoming increasingly popular in remote sensing applications. They can carry a variety of sensors, including cameras, LiDAR and thermal sensors, and can be used to capture data in areas that are difficult or dangerous to access by other means. In summary, remote sensing involves the use of various platforms and sensors to capture, record and analyze data from the electromagnetic spectrum. These platforms and sensors include aerial photography, satellite imaging, LiDAR, radar, GPS, and drones. (c ) What are the weathering stages of soil formation? Discuss the active and passive factors of soil formation. 15
Soil formation is a complex process that occurs over a long period of time, typically over hundreds or thousands of years. The process of soil formation involves the physical and chemical breakdown of rock, as well as the addition of organic material and water. Soil formation can be divided into several stages, including weathering, leaching, accumulation, and humification. In this response, we will focus on the weathering stage and discuss the active and passive factors that influence soil formation.
Weathering is the first stage of soil formation, and it involves the physical and chemical breakdown of rocks and minerals. There are two types of weathering: mechanical and chemical. Mechanical weathering is the physical breakdown of rock into smaller pieces. Chemical weathering, on the other hand, involves the chemical breakdown of rock into new compounds.
The active factors that influence the weathering stage of soil formation include the following:
Climate: Climate is a critical factor in soil formation, as it determines the amount of precipitation and temperature variations that occur in an area. High rainfall and high temperatures can increase the rate of chemical weathering, while low rainfall and low temperatures can slow it down.
Parent Material: The type of rock that soil forms from influences the weathering process. For example, soft sedimentary rocks weather faster than hard igneous rocks.
Topography: The slope and aspect of an area can also influence soil formation. Areas with steep slopes and a lot of erosion may not have as much soil accumulation as areas with gentle slopes.
Biota: The presence of plant roots and soil organisms can speed up the weathering process by breaking down rocks and minerals.
The passive factors that influence the weathering stage of soil formation include the following:
Time: Soil formation is a slow process that occurs over long periods of time. The longer an area is exposed to weathering, the more developed the soil will be.
Relief: The physical characteristics of an area, including its slope, aspect, and drainage patterns, can influence soil formation by determining the amount of erosion and deposition that occurs.
Parent Material: The chemical composition of the rock that soil forms from can influence the chemical weathering process.
Climate: Although climate is also an active factor, it can be considered passive as it cannot be directly controlled or influenced by humans.
In conclusion, soil formation is a complex process that occurs over a long period of time. The weathering stage of soil formation involves the physical and chemical breakdown of rocks and minerals. Both active and passive factors influence the weathering stage, including climate, parent material, topography, biota, time, relief, and parent material. Understanding these factors is critical for managing soil resources and maintaining healthy soils. SECTION—B 5. Answer the following questions in about 150 words each: 10x5=50 (a) Diagrammatically explain the types of biozonation. Biozonation is the division of a geological time period into zones based on the presence of certain fossil groups. The following are the types of biozonation: Chronostratigraphic Biozonation: This type of biozonation is based on the relative ages of rocks and their position in the geological time scale. It involves the identification of major boundaries in the geological time scale, such as the boundaries between periods and epochs. Lithostratigraphic Biozonation: This type of biozonation is based on the lithology or rock type of the strata in which fossils are found. It involves the identification of specific rock formations or groups that contain characteristic fossils. Biostratigraphic Biozonation: This type of biozonation is based on the identification of characteristic fossils within rock strata. It involves the identification of zones based on the occurrence or disappearance of particular species or groups of species. Ecological Biozonation: This type of biozonation is based on the ecological characteristics of the fossil groups found within rock strata. It involves the identification of zones based on the occurrence or disappearance of particular communities of species. Here is a diagrammatic representation of the types of biozonation: GEOLOGICAL TIME SCALE _______________________________________ | | Chronostratigraphic Lithostratigraphic Biostratigraphic Ecological Biozonation Biozonation Biozonation Biozonation | | In summary, the types of biozonation include chronostratigraphic, lithostratigraphic, biostratigraphic, and ecological biozonation. Each type is based on different criteria, such as relative ages of rocks, rock type, fossil groups, and ecological characteristics. (b) Define index fossil and discuss its significance. Give the examples of index fossils of Palaeozoic Era. Index fossils are the remains or impressions of organisms that were widespread geographically and existed for a relatively short period of time. These fossils are used by geologists and paleontologists as markers for dating and correlating rock layers, and for reconstructing the geologic history of the Earth. The significance of index fossils is that they provide a means for determining the relative ages of rocks and fossils. By examining the distribution of these fossils in different rock layers, scientists can establish a chronological sequence of events and create a relative time scale. This allows them to correlate rock formations across large distances and to make accurate comparisons between different regions. Index fossils of the Palaeozoic Era (540 million to 251 million years ago) include trilobites, graptolites, ammonites, and brachiopods. Trilobites were arthropods with a hard, segmented exoskeleton and were abundant in the Cambrian, Ordovician, and Silurian periods. Graptolites were small, colonial marine animals that lived in the ocean and were used to date rocks from the Ordovician to the Devonian periods. Ammonites were cephalopods with coiled shells and were common in the oceans of the Mesozoic Era. Brachiopods were marine animals with hinged shells and were widespread throughout the Palaeozoic Era. By using these and other index fossils, scientists can determine the relative ages of rocks and fossils, and gain a better understanding of the history of life on Earth. (c) Describe the lithostratigraphy, palaeoenvironment and age of Blaini Formation. The Blaini Formation is a sedimentary rock formation located in the western Himalayas of Pakistan, and it consists of interbedded sandstone, siltstone, shale, and limestone. Here's a description of the lithostratigraphy, palaeoenvironment, and age of the Blaini Formation: Lithostratigraphy: The Blaini Formation is part of the Murree Formation, which is a sequence of sedimentary rocks that were deposited during the Paleogene period (66 to 23 million years ago). The Blaini Formation is made up of several distinct lithological units, including the Sakhakot Sandstone, Chorgali Formation, and Sakessar Limestone. These units are separated by unconformities, indicating periods of erosion and non-deposition. Palaeoenvironment: The Blaini Formation was deposited in a shallow marine environment, possibly a deltaic setting, with periodic influxes of freshwater. The presence of sedimentary structures such as ripple marks and cross-bedding suggest that the sediment was deposited by currents, such as tidal currents or storm waves. The limestone beds in the formation suggest the presence of carbonate-producing organisms, indicating a relatively warm and shallow marine environment. Age: The Blaini Formation has been dated to the early Eocene epoch, which lasted from approximately 56 to 34 million years ago. This age has been determined through the study of fossil assemblages found in the formation, including foraminifera, ostracods, and molluscs. The fossils suggest a relatively shallow marine environment, consistent with the lithological characteristics of the formation. Overall, the Blaini Formation provides important information about the geologic history and paleoenvironment of the western Himalayas during the Paleogene period. Its sedimentary characteristics and fossil content allow scientists to reconstruct the ancient environments and ecosystems that existed in this region millions of years ago.
(d) What are the different sources for saline water intrusion in aquifers? Describe Ghyben-Herzberg relation.
Saline water intrusion in aquifers can occur due to a variety of reasons. Here are some of the different sources of saline water intrusion in aquifers:
Natural saltwater intrusion: This occurs when saline water from the ocean or other saline sources migrates into coastal aquifers due to natural geological processes.
Human-induced saltwater intrusion: This occurs when humans extract groundwater faster than it can be recharged, causing a reduction in the freshwater head and an increase in the saltwater head.
Leakage from saline water bodies: Saline water bodies such as salt lakes or marshes can also cause saline water intrusion in nearby aquifers if there is a hydraulic connection between the two.
Land use changes: Land use changes such as urbanization or agricultural practices can cause changes in the hydrology of an area, leading to saline water intrusion in aquifers.
The Ghyben-Herzberg relation is a theoretical relationship between the elevation of the freshwater-saltwater interface in a coastal aquifer and the elevation of the water table above sea level. It was first proposed by Dutch hydrologist A. Ghyben in 1888 and later refined by German hydrologist E. Herzberg in 1901.
According to the Ghyben-Herzberg relation, the thickness of the freshwater lens (the layer of freshwater floating on top of denser saltwater) is approximately 40 times the height of the water table above sea level. In other words, if the water table is 1 meter above sea level, the thickness of the freshwater lens will be around 40 meters.
This relationship holds true only for idealized conditions, such as a homogeneous and isotropic aquifer and no lateral flow of groundwater. In real-world situations, the Ghyben-Herzberg relation is a useful tool for estimating the thickness of the freshwater lens and predicting the potential for saltwater intrusion in coastal aquifers.
(e) What are the geological investigations required for civil engineering projects of dams, reservoirs and tunnels?
Geological investigations play a crucial role in the planning, design, and construction of civil engineering projects such as dams, reservoirs, and tunnels. Here are some of the key geological investigations required for these projects:
Geological mapping: Detailed geological mapping of the project area is essential to understand the geological structure, lithology, and distribution of faults, fractures, and other geological features that could impact the project.
Geophysical surveys: Geophysical surveys, such as seismic reflection, resistivity, and ground-penetrating radar, can provide valuable information about the subsurface geology and help identify potential geohazards.
Borehole drilling and sampling: Borehole drilling and sampling are used to obtain rock and soil samples for laboratory analysis, as well as to assess the subsurface conditions and geology.
Laboratory testing: Laboratory testing of rock and soil samples can provide information about their physical and mechanical properties, as well as their susceptibility to erosion, deformation, and weathering.
Slope stability analysis: Slope stability analysis is essential for dams and reservoirs, as it helps to identify potential failure modes and determine the design parameters for the slopes.
Seismic hazard analysis: Seismic hazard analysis is necessary for projects located in seismically active regions, such as dams and tunnels, as it helps to identify potential earthquake hazards and determine the design parameters for seismic safety.
Hydrological studies: Hydrological studies are essential for dams and reservoirs, as they provide information about the water flow and storage characteristics of the project area.
Geological hazard assessment: Geological hazard assessment is essential for tunnels, as it helps to identify potential geological hazards such as rock falls, landslides, and ground collapse.
Overall, geological investigations are critical for civil engineering projects of dams, reservoirs, and tunnels, as they help to identify potential geological hazards, determine the design parameters for the project, and ensure its safe and effective construction.
6. (a) Elucidate the evolutionary trend of Hominidae with examples of Indian occurrence.
The family Hominidae comprises of modern humans (Homo sapiens) and their extinct relatives, including various species of early hominins. The evolutionary trend of Hominidae can be divided into several key phases, as outlined below, along with examples of Indian occurrence:
Sahelanthropus tchadensis: This species lived about 7-6 million years ago in Chad, Africa. It is believed to be one of the earliest members of the Hominidae family, but its exact place in human evolution is still debated.
Orrorin tugenensis: This species lived about 6 million years ago in Kenya. It is believed to have been bipedal, but its anatomy is still poorly understood.
Ardipithecus ramidus: This species lived about 4.4 million years ago in Ethiopia. It is believed to have been bipedal and lived in woodland environments.
Australopithecus afarensis: This species lived about 3.9-2.9 million years ago in East Africa. The most famous specimen of this species is "Lucy," a nearly complete skeleton found in Ethiopia in 1974. A. afarensis is believed to have been bipedal and lived in a range of environments.
Homo habilis: This species lived about 2.8-1.5 million years ago in East Africa. It is considered one of the earliest members of the Homo genus and is known for its stone tool-making abilities.
Homo erectus: This species lived about 1.9 million-70,000 years ago in Africa, Asia, and Europe. It was the first hominin to leave Africa and spread to other parts of the world. In India, fossils of Homo erectus have been found in various locations, including the Narmada Valley, the Siwalik Hills, and the Andaman Islands.
Homo sapiens: This species evolved in Africa about 300,000 years ago and spread to other parts of the world, including India. In India, the earliest evidence of Homo sapiens comes from the Bhimbetka rock shelters in Madhya Pradesh, where rock paintings dating back to around 30,000 years ago depict modern humans engaged in various activities.
Overall, the evolutionary trend of Hominidae in India is characterized by the presence of Homo erectus fossils in various locations, along with evidence of modern humans in the form of rock art and other archaeological remains. These findings provide important insights into the evolution of our species and its spread across the globe.
(b) Describe the Palaeozoic sequence of Kashmir Valley with fossils content.
The Palaeozoic sequence of the Kashmir Valley is a significant geological unit that contains a wide range of sedimentary rocks and fossils that date back to the Paleozoic era. The sequence can be divided into several distinct formations, each with its unique lithology and fossil content, as outlined below:
Panjal Traps: This formation is composed of extensive lava flows of basaltic and andesitic composition that are believed to have erupted during the late Cretaceous period. The Panjal Traps form the lowest stratigraphic unit of the Kashmir Valley and are not known to contain any significant fossil content.
Wadia Formation: This formation is composed of alternating layers of shale, sandstone, and limestone that date back to the early Carboniferous period. The Wadia Formation contains a diverse range of marine fossils, including brachiopods, bryozoans, crinoids, and corals.
Dwyka Formation: This formation is composed of glacial deposits, including sandstones, shales, and conglomerates, that are believed to have been deposited during the late Carboniferous period. The Dwyka Formation is not known to contain any significant fossil content.
Lower Permian Formation: This formation is composed of alternating layers of sandstone, shale, and coal that date back to the early Permian period. The Lower Permian Formation contains a diverse range of plant fossils, including ferns, horsetails, and seed plants.
Upper Permian Formation: This formation is composed of thick layers of sandstone, shale, and limestone that date back to the late Permian period. The Upper Permian Formation contains a diverse range of marine fossils, including brachiopods, bryozoans, ammonoids, and gastropods.
Zewan Formation: This formation is composed of shale, sandstone, and conglomerate that date back to the Triassic period. The Zewan Formation contains a diverse range of plant fossils, including ferns, horsetails, and seed plants.
Overall, the Palaeozoic sequence of the Kashmir Valley provides important insights into the geological and biological history of the region. The presence of diverse fossil assemblages in different formations provides evidence of the changing environmental conditions and the evolution of life forms over time.
(c) Describe the surface investigation methods of groundwater. 15
Surface investigation methods are used to gather information about the properties of the subsurface geological formations that can affect groundwater flow and storage. These methods can help identify potential sources of contamination or areas with high water-bearing capacity. Some common surface investigation methods for groundwater are:
Geologic mapping: Geologic maps provide information about the distribution, orientation, and properties of rock formations and soils that can affect groundwater movement. This information can be used to identify potential areas of recharge, discharge, and flow paths.
Geophysical surveys: Geophysical methods involve measuring the physical properties of subsurface materials, such as their electrical conductivity, magnetic susceptibility, or seismic wave velocity. These methods can help identify the location, depth, and extent of groundwater-bearing formations and detect geological structures that may influence groundwater flow.
Groundwater level monitoring: Monitoring groundwater levels over time can provide information about the hydraulic properties of the subsurface formations, including the depth and extent of the water table, recharge rates, and variations in water level due to pumping or seasonal changes.
Pumping tests: Pumping tests involve pumping water from a well at a constant rate while monitoring the water level and the rate of water flow into the well. This information can be used to estimate the hydraulic properties of the aquifer, including its transmissivity and storage capacity.
Soil sampling and analysis: Soil samples can be collected from boreholes or trenches and analyzed for their physical and chemical properties, including permeability, porosity, and contamination levels. This information can be used to assess the suitability of the soil and underlying formations for groundwater storage or to identify potential sources of contamination.
Overall, surface investigation methods provide valuable information about the subsurface geological formations and their properties that can affect groundwater flow and storage. These methods can help inform decisions about the location, design, and management of groundwater resources for various purposes, including drinking water supply, irrigation, and industrial uses.
7. (a) Describe the stratigraphy of Singhbhum Craton and discuss its economic significance.
The Singhbhum Craton is a major geological unit in eastern India that contains a diverse range of rocks and minerals, including iron, copper, gold, and uranium deposits. The stratigraphy of the Singhbhum Craton can be divided into several distinct formations, as outlined below:
Iron Ore Group: This formation is composed of banded iron formations (BIFs) that date back to the Archean Eon, around 3.5 billion years ago. The Iron Ore Group is one of the most important formations in the Singhbhum Craton, containing extensive deposits of high-grade iron ore that are mined for the production of steel.
Dhanjori Formation: This formation is composed of quartzite, shale, and phyllite that date back to the Archean Eon. The Dhanjori Formation contains several layers of BIFs, as well as minor copper and gold deposits.
Iron Formation-Manganese Formation (IF-MF): This formation is composed of alternating layers of BIFs and manganese-rich sediments that date back to the Paleoproterozoic Era, around 2.5 billion years ago. The IF-MF contains extensive iron ore and manganese deposits that are mined for various industrial uses.
Sillimanite-Biotite Gneiss: This formation is composed of metamorphosed sedimentary rocks that date back to the Paleoproterozoic Era. The Sillimanite-Biotite Gneiss contains minor copper and gold deposits.
Chotanagpur Granite Gneiss: This formation is composed of granitic and gneissic rocks that date back to the Neoproterozoic Era, around 1 billion years ago. The Chotanagpur Granite Gneiss contains minor uranium deposits.
The economic significance of the Singhbhum Craton lies in its extensive mineral resources, particularly its iron, copper, gold, and uranium deposits. The Iron Ore Group alone contains some of the largest and highest-grade iron ore deposits in the world, making India one of the top producers and exporters of iron ore. The IF-MF formation also contains significant manganese deposits, which are used in the production of steel and other alloys. The minor copper and gold deposits in the Dhanjori and Sillimanite-Biotite Gneiss formations are also of economic importance. Additionally, the Chotanagpur Granite Gneiss contains minor uranium deposits, which are used for nuclear power generation. Overall, the mineral resources of the Singhbhum Craton play a significant role in India's industrial development and economy.
(b )Discuss the effects on dead organism after burial. 15
When an organism dies and is buried, a complex set of physical, chemical, and biological processes begin to take place that ultimately result in the formation of fossils. The effects on a dead organism after burial can be summarized as follows:
Decay: After death, the organism begins to decompose due to the action of bacteria and other microorganisms. This process can result in the loss of soft tissues and the release of gases such as methane and carbon dioxide.
Burial: If the organism is buried quickly after death, it may be protected from scavengers and further decay. Burial can also provide a stable environment for the preservation of the organism's remains.
Compaction: Over time, layers of sediment may accumulate on top of the buried organism, exerting pressure that can cause the sediment to become compacted. This process can help to preserve the structure of the organism's remains.
Mineralization: As the buried organism decays, its remains may be replaced by minerals such as silica or calcium carbonate. This process can result in the formation of a fossil, which is a mineralized copy of the original organism.
Fossilization: Under certain conditions, the mineralized remains of the organism may be preserved over millions of years, resulting in the formation of a fossil. Fossils can provide important information about the evolution and biology of extinct organisms.
The effects on a dead organism after burial can vary depending on a range of factors, including the type of organism, the conditions of burial, and the geological processes that take place over time. Overall, the process of fossilization is a rare event, and only a small fraction of all organisms that have ever lived have been preserved as fossils. However, the fossils that do exist provide a valuable window into the history of life on Earth and have helped to shape our understanding of the natural world.
(c ) Describe the types of landslide, and discuss its factors and mitigation measures.
Landslides are the movement of rocks, soil, or debris down a slope, caused by a variety of natural and human-induced factors. Landslides can be classified into different types based on the material that moves and the way it moves. The three main types of landslides are:
Rockfall: This occurs when rocks detach and fall from steep slopes. Rockfalls can be triggered by weathering, erosion, or seismic activity.
Debris flow: This occurs when a mass of debris, including soil, rocks, and water, moves down a slope. Debris flows are common in areas with steep terrain and heavy rainfall.
Landslide: This occurs when a mass of soil or rock moves downslope along a failure plane. Landslides are often triggered by heavy rainfall, earthquakes, or human activity.
Factors that contribute to landslides include geological, hydrological, and human factors. Geological factors include the slope angle, rock type, and weathering. Hydrological factors include rainfall intensity and soil saturation. Human factors include land use changes, deforestation, and excavation.
Mitigation measures for landslides can be divided into two categories: structural and non-structural. Structural measures include building retaining walls, installing drainage systems, and constructing slope stabilization structures. Non-structural measures include land use planning, zoning regulations, and early warning systems. Effective mitigation measures require a combination of both structural and non-structural measures. It is also essential to raise public awareness of the risks associated with landslides and the importance of adopting measures to reduce those risks.
8. (a) Give an account of interpretation of groundwater chemical quality through various graphic representation methods.
Groundwater quality can be interpreted by analyzing the chemical constituents present in the water. Various graphical representation methods are used to understand and interpret the quality of groundwater. Some of the most commonly used methods are:
Piper diagram: This is a graphical representation that displays the chemical composition of groundwater. The diagram is divided into three sections: cations, anions, and the percentage of total dissolved solids (TDS). The cations and anions are plotted on the x and y-axis, respectively, and the percentage of TDS is represented by the size of the circle. The piper diagram is useful for identifying the dominant ions in the groundwater.
Stiff diagram: This is a graphical representation that displays the concentration of different chemical constituents in the groundwater. The diagram is divided into two sections: cations and anions. The concentration of each chemical constituent is plotted on the x and y-axis, respectively. The diagram is useful for identifying the source of contamination in the groundwater.
Box plot: This is a graphical representation that displays the distribution of chemical constituents in the groundwater. The box plot shows the minimum and maximum values, median, and quartiles of the chemical constituents. The box plot is useful for identifying the outliers in the dataset.
Scatter plot: This is a graphical representation that displays the relationship between two chemical constituents in the groundwater. The concentration of one chemical constituent is plotted on the x-axis, and the concentration of another chemical constituent is plotted on the y-axis. The scatter plot is useful for identifying the correlation between different chemical constituents.
Time-series plot: This is a graphical representation that displays the changes in the concentration of chemical constituents in the groundwater over time. The concentration of each chemical constituent is plotted on the y-axis, and the time is plotted on the x-axis. The time-series plot is useful for identifying the trends in the groundwater quality over time.
In summary, these graphical representation methods help to interpret the groundwater quality by providing insights into the chemical composition, concentration, source of contamination, distribution, correlation, and trends in the groundwater.
(b) Describe the Lower Gondwana flora of India and their significance. 15
The Lower Gondwana flora refers to the plant fossils found in the sedimentary rocks of the Gondwana basin in India, which dates back to the Permian and Triassic periods, approximately 280 to 200 million years ago. The Lower Gondwana flora is considered significant for several reasons:
Diverse plant species: The Lower Gondwana flora is known for its diversity, with more than 150 species of plants identified from the fossils. This includes gymnosperms, ferns, and other types of plants.
Evolutionary significance: The Lower Gondwana flora provides important insights into the evolution of plants during the Permian and Triassic periods. The fossils show the development of different plant structures, such as leaves, stems, and roots, as well as the emergence of new plant groups.
Climate information: The Lower Gondwana flora can also provide information about the climate and environment during the Permian and Triassic periods. For example, the presence of Glossopteris fossils in the Lower Gondwana rocks suggests a cool, moist climate.
Economic importance: Some of the plants found in the Lower Gondwana rocks have economic significance. For example, the Glossopteris flora includes several species of plants that were important as coal-forming plants, and the seeds of some of the gymnosperms found in the Lower Gondwana rocks were used as food by early human ancestors.
In summary, the Lower Gondwana flora of India is significant for its diversity, evolutionary significance, ability to provide insights into past climates and environments, and economic importance.
(c) Describe the chronostratigraphic classification of geological time scale.
The chronostratigraphic classification of the geological time scale is a way of dividing Earth's history into units based on the relative ages of rocks and fossils. This classification system is used by geologists and paleontologists to study the timing and sequence of events in Earth's history. The chronostratigraphic classification is composed of four main categories: eons, eras, periods, and epochs.
Eons: Eons are the largest units of the chronostratigraphic classification, representing the longest spans of geological time. The current eon is the Phanerozoic eon, which began around 541 million years ago and continues to the present day. The Phanerozoic eon is further divided into three eras: the Paleozoic, Mesozoic, and Cenozoic eras.
Eras: Eras are the second largest units of the chronostratigraphic classification and represent significant periods of geological time. Each era is characterized by distinctive geological, biological, and environmental events. For example, the Paleozoic era, which began around 541 million years ago and lasted for about 291 million years, saw the emergence of complex life forms such as fish, amphibians, and reptiles.
Periods: Periods are the third largest units of the chronostratigraphic classification and represent subdivisions of eras. Periods are generally defined by significant geological and biological events, such as the appearance or extinction of particular groups of organisms. For example, the Jurassic period, which lasted from 201 million to 145 million years ago, was characterized by the dominance of dinosaurs.
Epochs: Epochs are the smallest units of the chronostratigraphic classification and represent subdivisions of periods. Epochs are characterized by smaller-scale events, such as fluctuations in climate or sea level. For example, the Eocene epoch, which lasted from 56 million to 33.9 million years ago, was characterized by a global warming event that led to the diversification of mammals.
The chronostratigraphic classification of the geological time scale is continually refined as new geological and paleontological data are gathered, and as new discoveries are made about Earth's history.