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# IAS 2022 OPTIONAL GEOLOGY PAPER SOLUTION with complete solve analysis diagram complete solution

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.

Ans Explain 'convergent plate boundary' with suitable examples.

A convergent plate boundary is a type of tectonic plate boundary where two plates move towards each other and collide. The collision may result in the formation of mountains, volcanoes, or earthquakes. There are three types of convergent plate boundaries:

1. Oceanic-Continental Convergent Boundary: This occurs when an oceanic plate collides with a continental plate. The oceanic plate is denser than the continental plate and sinks beneath it in a process called subduction. This creates a deep ocean trench and causes volcanic activity on the continental plate. The Andes Mountains in South America are an example of an oceanic-continental convergent boundary. 2. Oceanic-Oceanic Convergent Boundary: This occurs when two oceanic plates collide. One plate subducts beneath the other, creating a deep ocean trench. The subducting plate melts as it descends, creating magma that rises to the surface and forms volcanic islands. The Aleutian Islands in Alaska are an example of an oceanic-oceanic convergent boundary. 3. Continental-Continental Convergent Boundary: This occurs when two continental plates collide. Because continental plates are less dense than oceanic plates, they do not subduct. Instead, the plates push against each other, creating a zone of deformation and uplift. This process can result in the formation of mountain ranges. The Himalayas are an example of a continental-continental convergent boundary.

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part 2

At convergent plate boundaries, earthquakes occur due to the collision or subduction of two tectonic plates. These earthquakes tend to be deeper and more powerful than those at other types of plate boundaries, often reaching magnitudes of 7.0 or higher. The reason for this is that as the two plates collide or one plate is forced beneath the other, immense pressure builds up along the boundary, which eventually causes the rocks to fracture and shift, resulting in an earthquake. These earthquakes at convergent boundaries can also be associated with other geological phenomena, such as volcanic eruptions and tsunamis, which can further add to their destructive potential. As such, it is important for those living in areas near convergent plate boundaries to be aware of the potential risks and take appropriate safety measures.

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(b) What is the difference between Raster and Vector data? Describe characteristics as well as advantages and disadvantages Raster and Vector data .

Raster and vector data are two types of spatial data used in Geographic Information Systems (GIS). The main difference between the two types of data is the way they store and represent spatial information. Raster data is composed of a grid of cells or pixels, where each pixel contains a value representing a certain attribute such as elevation, temperature, or color. Raster data is often used for continuous data such as satellite imagery, aerial photography, and digital elevation models. Raster data is ideal for displaying continuous surfaces but can be challenging to edit or manipulate as the data is dependent on the resolution of the raster cell size. Vector data, on the other hand, uses points, lines, and polygons to represent features such as roads, buildings, and boundaries. Each feature is defined by its geographic location and attributes such as height, area, and name. Vector data is typically used for discrete or non-continuous data such as political boundaries or infrastructure assets. Vector data is ideal for editing or manipulation but can be challenging to display complex surfaces such as elevation or temperature. In summary, the main difference between raster and vector data is the way they represent spatial information. Raster data is composed of a grid of cells with values, while vector data is composed of points, lines, and polygons with attributes. Each type of data is useful for different purposes, and GIS applications often use both raster and vector data to create accurate and detailed maps and spatial analyses.

Part 2

Raster and vector data are two common types of spatial data used in Geographic Information Systems (GIS). Each has its own set of characteristics and advantages and disadvantages. Raster Data Raster data is made up of a grid of cells or pixels, where each pixel has a specific value representing a particular attribute. Common examples of raster data include satellite imagery, aerial photography, and digital elevation models. Characteristics of Raster Data:

• Raster data are continuous in nature, meaning that each pixel value represents a continuous variable, such as temperature or elevation.

• Raster data is often used to represent data that varies continuously over space, such as temperature, precipitation, or elevation.

• Raster data has a large file size due to the number of pixels that make up the image.

• Raster data can be easily manipulated and analyzed using various raster-based tools and techniques.

Advantages of Raster Data:

• Raster data is ideal for analyzing continuous data, such as temperature or precipitation.

• Raster data can be easily visualized using various color schemes to represent different values.

• Raster data is commonly used for remote sensing applications, such as satellite imagery or aerial photography.

Disadvantages of Raster Data:

• Raster data can have a large file size, which can be challenging to store and process.

• Raster data can lose resolution and detail when zoomed in or enlarged.

• Raster data can be prone to distortion or pixelation if not captured or processed correctly.

Vector Data Vector data is made up of points, lines, and polygons, which are used to represent real-world features such as roads, rivers, and boundaries. Each feature is represented as a series of coordinates that define its shape and location. Characteristics of Vector Data:

• Vector data is made up of discrete objects, such as points, lines, and polygons.

• Vector data is often used to represent features that have well-defined boundaries, such as land parcels, roads, or water bodies.

• Vector data has a smaller file size compared to raster data.

• Vector data can be easily manipulated and analyzed using various vector-based tools and techniques.

Advantages of Vector Data:

• Vector data is ideal for representing discrete features with well-defined boundaries, such as roads, land parcels, or building footprints.

• Vector data can be easily edited and updated as new information becomes available.

• Vector data can be used to perform spatial analysis, such as calculating distances between features or identifying features that intersect.

Disadvantages of Vector Data:

• Vector data can be challenging to visualize, especially when dealing with large datasets.

• Vector data can be less suitable for analyzing continuous data, such as temperature or elevation.

• Vector data can be prone to errors, such as topology errors, which can impact the accuracy of the data.

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(c)Illustrate and describe any five types of drainage pattern and give an account of the factors that influence drainage pattern development.

Drainage patterns refer to the network of streams and rivers that drain an area. The type of drainage pattern observed in an area is influenced by several factors, including topography, geology, and climate. Here are five types of drainage patterns and the factors that influence their development: 1. Dendritic Pattern: A dendritic pattern is the most common type of drainage pattern and is characterized by a branching network of streams. This pattern is formed on flat-lying or uniformly dipping rock, where streams follow the path of least resistance. 2. Radial Pattern: A radial pattern is characterized by streams that radiate outwards from a central point, usually a high point in the landscape, such as a mountain or volcano. This pattern is formed when the streams flow downhill in all directions from the central point. 3. Rectangular Pattern: A rectangular pattern is characterized by streams that flow along straight lines, which are often at right angles to each other. This pattern is formed in areas where the underlying rock is fractured or jointed, causing streams to follow the path of least resistance along the fractures. 4. Trellis Pattern: A trellis pattern is characterized by streams that flow parallel to each other with short, perpendicular tributaries. This pattern is formed in areas with alternating bands of resistant and less resistant rock, where streams follow the path of least resistance along the softer rock. 5. Parallel Pattern: A parallel pattern is characterized by streams that flow parallel to each other with no tributaries. This pattern is formed on steep slopes, where streams flow downhill in parallel paths. Factors that influence drainage pattern development include:

• Topography: The shape and slope of the land determine how water flows and how streams interact with each other.

• Geology: The type and structure of the rock beneath the surface determine the resistance to erosion and the path of least resistance for streams.

• Climate: The amount and intensity of rainfall and snowmelt can affect the amount of water flowing in streams and the erosive power of the water.

• Tectonic activity: Uplift and subsidence of the land can affect the slope of the land and the drainage patterns.

• Human activity: Human activities such as deforestation, agriculture, and urbanization can alter the landscape and change the natural drainage patterns.

(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 small-scale fold that form parallel to the axial surface of a larger fold. They result from the differential movement of layers within a fold due to the folding process, and are typically found in areas of complex deformation. The formation of drag folds can be explained by considering the behavior of layers within a fold. In a syncline (downward-pointing fold), the layers near the center of the fold are compressed and shortened, while the layers on the outer edges of the fold are stretched and lengthened. As a result, the layers near the center of the fold may be forced to slide along the layers on the outer edges of the fold, creating a series of small, secondary folds that are oriented parallel to the axial surface of the larger fold. In an anticline (upward-pointing fold), the opposite process occurs, with the layers near the center of the fold being stretched and lengthened, and the layers on the outer edges of the fold being compressed and shortened. This can also lead to the formation of drag folds that are oriented parallel to the axial surface of the larger fold. Drag folds can be useful in determining the major fold structure of a geological formation. By examining the orientation and spacing of drag folds within a larger fold, geologists can infer information about the shape and geometry of the fold. For example, the presence of closely spaced, tightly folded drag folds can indicate that the larger fold is steeply plunging, while widely spaced, gently folded drag folds can suggest a more gently dipping fold. Overall, the study of drag folds can provide valuable insights into the complex processes of deformation and folding that shape the Earth's crust.

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