Representation of Geographical Features Chapter Notes | Geography Class 8 ICSE PDF Download

Introduction

Topographic Maps

• Topographic maps are large-scale maps showing the Earth's surface features using symbols.
• They depict natural features (mountains, plateaus, plains) and man-made features (dams, roads).
• Elevation is shown in feet or metres, indicating height above sea level.
• Contour lines connect points of equal elevation to represent landforms, slopes, and relief:
  • Elevation is the height of a place above sea level, ranging from a few metres to thousands of metres.
  • Slope indicates how steep the land is; closely spaced contour lines show steep slopes, while sparsely spaced lines indicate flat land.
  • Relief is the difference between the highest and lowest elevations in an area.

Contour

• Contour lines are found only on large-scale topographic maps.
• Index contours are bold lines with elevation marked, often occurring every fifth contour line.
• Intermediate contours lie between index contours, e.g., five intermediate contours between 300m and 400m with a 20m interval.
• Contour interval is the altitude difference between two successive contour lines.
• Distance between contour lines indicates the type of slope:
  • Closely grouped contours show a steep slope.
  • Spaced-out contours indicate a gradual slope.
  • Evenly spaced contours represent a uniform slope.
  • Widely spaced contours suggest a gentle slope.
  • Widely spaced contours at a hilltop indicate a flat hilltop.
• Contour lines form a 'V' shape along valleys, pointing upstream to show stream flow direction.
• Streams flow downhill, and contours can cross streams.
• Contour lines never touch or cross, except in vertical cliffs where they appear stacked.
• Stacked contours indicate a cliff.

Mapping Landforms through Contours

• Topographic maps use symbols to represent natural landforms.
• Understanding contour patterns helps identify landforms like slopes, hills, plateaus, ridges, saddles, passes, and cols.

Slopes

• Slope is the rate of ascent or descent of the ground.
• Closer contour lines indicate steeper slopes; farther apart lines show gentler slopes:
  • Gentle slope: Evenly spaced, widely apart contour lines.
  • Steep slope: Evenly spaced, closely placed contour lines.

Hill

• A hill is an area of high ground with slopes descending in all directions.
• Shown by a single closed contour line or concentric closed contour lines.
• The smallest closed circle represents the hilltop.
• More contour lines indicate a higher hill.

Plateaus

• Plateaus are broad highlands with flat tops, rising abruptly from surrounding land.
• Depicted by evenly spaced contour lines surrounding an area with few or no lines, indicating a flat top.

Ridge

• A ridge is a narrow, elongated range of hills with a sharp crest and multiple peaks.
• Slopes are steep-sided, shown by elongated or oval, closely spaced contour lines.

Saddle

• A saddle is a low point between two areas of higher ground, not always between hilltops.
• Contour lines form an hourglass or figure-eight shape.
• The depression is broad and low, resembling a horse’s saddle.

Passes

• Passes are low points or openings between peaks in a mountain or hill range.
• Provide passage across mountains, shown as empty spaces between two closed contour lines representing peaks.

Col

• A col is the lowest point on a mountain ridge between two peaks, also called a notch or gap.
• It is narrow and steep-sided, unlike a broader saddle.

Gap

• A gap is a low-lying area between two elevated landmasses, like mountains.
• More rugged and harder to navigate than passes, e.g., the South Col between Mount Everest and Lhotse.

Settlements

• Settlements are places where people establish residential communities, varying from single dwellings to large cities.
• Can be temporary (occupied briefly) or permanent (occupied for a long time).
• Other types include holiday resorts, markets, towns, ports, and industrial towns, classified by their main functions.

Classification of Settlements

• Rural settlements rely on primary activities like agriculture, animal husbandry, and fishing.
• Characteristics include water supply, fertile lands, relief features, building materials, and scattered populations.
• Urban settlements are larger, with people engaged in secondary (manufacturing) or tertiary (trading, services) activities.
• Urban infrastructure includes concrete buildings, bridges, roads, and developed transport systems.

Patterns of Rural Settlements

• Dispersed settlements: Houses are far apart, often interspersed with fields, with centralized markets.
• Compact or nucleated settlements: Houses are built close together, common in fertile plain regions.
• Linear settlements: Constructed along roads, railways, rivers, canals, valley edges, or levees.
• Radial settlements: Houses spread out from a central point along streets in all directions.

Interpretation of Topographical Sheets

Marginal Information

• Name of the topographical sheet.
• Number of the topographical sheet.
• Area shown on the sheet.
• Area covered in square kilometres.
• Latitudinal and longitudinal extent.
• Extent of the grid.
• Scale of the topographical sheet.
• Special information, if any.

Relief Features and Drainage

• Contour intervals on the sheet.
• Physical divisions on the sheet.
• Description of relief features in each physical division.
• Major landforms and their locations.
• Drainage pattern.
• Prominent water bodies.
• General slope of the area.
• Gradient and direction of important rivers.

Prominent Land Uses

• Types of natural vegetation.
• Distribution patterns of natural vegetation.
• Major types of possible land uses.
• Main occupations, such as lumbering, livestock raising, farming, mining, and industries.

Means of Transport and Communication

• Transport and communication means shown on the sheet, like tracks, footpaths, roads, railways, telegraph, telephone lines, and post offices.
• Correlation between topography and transport/communication means.

Human Settlements

• Urban and rural centres, their size, and location.
• Settlement patterns.
• Special activities in urban centres, such as industries, mining, trading, administrative, and defence.
• Density and pattern of rural settlements.
• Information on land use and major occupations.

Profile of Survey Map 45 D/7

• Description of the area covered by Survey Sheet No. 45 D/7 (Gujarat and Rajasthan).
  • Districts: Banaskantha (Gujarat) and Sirohi (Rajasthan).
  • Location: Latitude 24°20' North, Longitude 72°25' East.
• Region lies in western India, on the borders of Rajasthan and Gujarat, at the southern end of the Aravalli Hills, northeast of Sheet 45 D/10.

Relief

• Area is mainly flat, except for the east-central region where hills rise to nearly 500 metres.
• Lower hills in the northeast corner.
• Land slopes from northeast to southwest in the northern half and east to west in the southern half, indicated by river flow.

Drainage

• Banas River flows westward into the swampland of the Little Rann, northeast of the Gulf of Kutch.
• Has numerous smaller streams, with the Balaram Nadi as a left-bank tributary from the southeast.
• River width varies from 0.25 km to over 1 km, with a narrow perennial watercourse.
• Dry portions fill during the rainy season.

Natural Vegetation

• Hilly areas: Dry deciduous forests of small trees
• ​Plains: Shrubs and thorny trees where there is no agriculture
• Irrigation: Region dependent on the periodic rainfall (monsoon), tanks and wells for agriculture
• Occupations: Agriculture and rearing of cattle, sheep, camels and horses
• Communication: Except for the main line of the Western Railway and the road that runs across the south-east corner of the map through Chitrasani, there are no other important communication links. All the other settlements are linked by cart tracks.
• Settlements: Except for Chitrasani which is a rail/road centre, all the settlements are small and widely scattered chiefly in the lowland area and are either in a nucleated or dispersed pattern.