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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:

  1. 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.

  2. 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.

  3. 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.

  4. 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:

  1. 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.

  2. 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.

  3. Parent Material: The chemical composition of the rock that soil forms from can influence the chemical weathering process.

  4. 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: