Class 11 Geography Methods of Relief Representation Notes: Methods of Relief Representation is the fifth chapter in CBSE Class 11 Geography, which discusses the concept of topographical Maps and their various forms.
In Class 11 Geography, we learn about different ways to show the shape and features of the land on maps. These methods are important because they help us understand how the land looks. One way is using contour lines, which connect points of the same height on a map. Another way is shading, where we use different colours to show how light and shadow fall on the land. We also use short lines called hachures to show steep slopes and valleys. By learning these methods, we can better understand maps and the land they represent.
The Methods of Relief Representation notes cover all the necessary topics that are extremely important for the examination 2024. It can save you time and will positively affect your results.
Methods of Relief Representation| Class 11 Geography
Methods of Representing Relief Features
Various methods are used to show the shape and features of the land on maps. These methods include hachures, contours, form lines, spot heights, bench marks, trigonometrical points, hill shading, and layer coloring. Each method has its advantages and disadvantages in representing the relief of the land.
- Hachures: Hachures are small lines drawn to represent slopes, with thicker lines indicating steeper slopes and thinner lines for gentler slopes. Slopes above 45° are shown completely in black.
- Contours: Contours are imaginary lines connecting places with the same elevation above sea level, usually drawn in brown.
- Form Lines: Form lines are similar to contours but represent features not actually surveyed, shown as broken lines.
- Spot heights: Spot heights indicate the actual height above sea level of surveyed places, shown as dots with their respective values.
- Bench marks: Bench marks indicate the height of tall structures like buildings or bridges, marked with the letters BM and the height.
- Trigonometrical Stations: Trigonometrical Stations are points in the triangulation survey, marked with a triangle symbol and the actual height.
- Hill Shading: Hill shading uses levels of gray to represent relief by showing the shadows that would be cast by elevated areas.
- Layer coloring: Layer coloring shows relief in layers, with each layer given a different color. This method is commonly used in physical maps to depict relief features, with blue representing water bodies, green for plains, various shades of brown for highlands, and white for snow-covered peaks.
Contours
Contours are a universal method used to represent the relief on maps. They typically measure elevation in meters above sea level. One advantage of contours is that they do not obscure other features on the topographic sheet. Reading contours is a valuable skill that allows us to understand the actual landscape depicted on the map. To interpret contours effectively, it’s important to understand their key features:
- Contours are drawn at regular intervals in brown color, with a common interval of 20 meters in 1:50,000 scale maps and 100 meters in 1:250,000 scale maps.
- Every fifth contour is drawn as a darker line to aid in map reading.
- The elevation value of each contour is indicated by breaking the contour line and is also provided at the edge of the topographic sheet.
- Contours generally do not intersect or cross each other. However, in the case of waterfalls and cliffs, contours may converge at the same point or line. In instances of overhanging cliffs, contours may intersect.
- Refer to Figure 10.10 for a visual representation of the general features depicted by contours.
Drawing of Contours and Their Cross Sections
The figure below illustrates how two adjacent hills are represented by contours.
a) Two adjacent hills shown by contours
Drawing cross-sections of contours helps in understanding the precise landforms depicted on the topographic sheet.
To draw a cross-section:
- Identify the area on the map where you want to draw the cross-section.
- Draw a straight line (AB) across the contours to indicate the path of the cross-section.
- Below the line AB, draw horizontal lines at regular intervals, representing the elevation levels indicated by the contours.
- Mark the elevation values on these horizontal lines, starting from the lowest elevation at the bottom.
- For each contour line that intersects line AB, mark the corresponding elevation on the vertical lines.
- Connect the points marked on the vertical lines to outline the shape of the landform.
- Shade the area between the outline and the line AB to represent the landform in the cross-section.
General instructions for identifying features shown in contours:
• A hill is depicted by circular contours with heights less than 1,000 meters.
• A plateau is an elevated land with an innermost contour roughly rectangular in shape and closely spaced outer contours.
• A ridge is a steep-sloped, elongated mountain with two or more peaks, shown by elliptical contour lines.
• A valley is a long depression with steep slopes formed by river erosion, depicted by contours bending sharply in a ‘V’ shape across the river.
• Spurs are land projections from higher to lower ground, with contours bending smoothly towards lower ground.
• Waterfalls are represented by contours meeting at the same point on a hill slope, with the difference between the highest and lowest contours indicating the waterfall’s height.
• A cliff is a steep-sloped exposure of a valley or coast, while a gorge is a very steep valley formed by river erosion.
• A volcano is shown by closed contours, with the innermost contours having lesser values, denoting the crater depression.
Conclusion
The ways we show the shape of the land on maps are very important. Each method, like drawing lines called contours or using symbols like hachures, helps us understand the land better. Contours show how high or low the land is, while hachures show how steep slopes are.
Other methods, like drawing spot heights or using colors, give us more details about the land. Drawing cross-sections helps us see the land’s shape more clearly. By using these methods together, we can understand maps better and learn about different places.
Related Links
- CBSE Notes Class 10 Geography Chapter 1- Resources and Development
- CBSE Notes Class 10 Geography Chapter 2- Forest and Wildlife Resources
- CBSE Class 10 Geography Notes Chapter 3 : Water Resources
- CBSE Class 10 Geography Notes Chapter 3 : Water Resources
FAQs on Class 11 Geography Methods of Relief Representation
What are relief representations in geography?
Relief representations in geography are methods used to depict the shape and elevation of the Earth’s surface on maps.
What are the common methods of relief representation?
Some common methods of relief representation include contours, hachures, spot heights, bench marks, and hill shading.
What are contours?
Contours are imaginary lines on a map that connect points of equal elevation above sea level. They help visualize the shape and height of the land.
How do hachures represent relief features?
Hachures are short lines drawn on maps to represent slopes. The lines are thicker for steeper slopes and thinner for gentler slopes.
What do spot heights indicate on a map?
Spot heights indicate the exact elevation of a specific point on the Earth’s surface above sea level.
How are bench marks used in relief representation?
Bench marks are markers placed at known elevations on the Earth’s surface, often on tall structures like buildings or bridges, to provide reference points for elevation measurements.
What is hill shading?
Hill shading is a method used to represent relief on a map by depicting the shadows that would be cast by elevated areas if illuminated from a particular direction.
How do relief representations help in understanding maps?
Relief representations help viewers understand the physical features of an area, such as mountains, valleys, and slopes, which is essential for interpreting maps accurately.