Topo_Imp terms

1 Grade: 10 (2022 Batch) Subject: Geography Topic: Topographical Maps (Important Terms) MAP: A map may be defined as a symbolic representation of Earth’s entire surface, or a part of its surface, on a flat sheet of paper, drawn to scale. Maps give spatial information and are a basic and indispensable tool used in various ways, depending on the requirements. They provide information about various aspects of an area, e.g. physical features, political boundaries, cultural diversity, and weather pattern. Cartography: The practice of drawing maps – has come a long way from the mere depiction of areas through drawings and sketches to digital mapping techniques with the use of satellites and computers for accurate mapping. Cartography employs scientific principles and techniques such as projection. Accurately representing the spherical surface of Earth on a flat sheet of paper is a major challenge faced by cartographers. Various statistical methods, signs, symbols, and colours are used to depict different features on a map. Classification of Maps: On the basis of scale On the basis of content and purpose Topographical maps: The word ‘topography’ is derived from two words – the Greek word ‘topos’, which means ‘place’, and the English word ‘graphy’, derived from the Greek word ‘graphia’ which means ‘writing’. Topographical maps are large-scale maps which show natural as well as man- made features of an area in great detail. The main characteristic of topographic Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

2 maps is that they show detailed relief features of land with the help of contour lines and also man-made or cultural features with conventional signs and symbols and colours. They are especially important for studying the regional geography since they depict a small area in great detail. They are extensively used by explorers. They serve as a critical tool in military missions and scientific explorations. They greatly facilitate regional administration, surveying, and planning. They are also a valuable research tool in conducting micro level studies of an area. Direction: It is shown on a map with the help of the north line, which is an arrow pointing towards the north. There are four cardinal/major directions on the map – north, south, east, and west. East, south, and west are located at angles of 90°, 180°, and 270°, respectively, from the north line in a clockwise direction. Between these major directions, we have intermediate directions like NE, SE, SW, and NW. North-east lies between north and east; south-east, between south and east; south-west, between south and west; and north-west, between north and west. Most maps are so drawn that the northern region is shown at the top. Scale: It is the ratio of the distance between any two points on a map to the actual distance between the corresponding points on the ground. The map scale is expressed in three different ways: Statement/verbal scale Graphical/linear scale/ Representative fraction Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

3 Important Terms used in Topo Sheets and their meanings: (Let us draw their conventional signs and symbols in true colour) Boundaries  International boundary: Forms boundary between countries  State boundary: Forms border between states within a country  District boundary: Forms border between districts within a state  Tehsil/Taluka boundary: Forms border between tehsils within a district  Tehsil/Taluka boundary: Forms border between tehsils within a district Roads and Railways  Expressway Highway: made up of concrete, without speed obstacles, and designed for swiftness  Broad gauge double: The horizontal distance between the tracks is 1,676 mm. Double signifies double line track in which each track is designated to allow train travel in each direction  Broad gauge single with station: The single tracks allows trains in both direction to share the same track  Railways under construction: Railway line under construction  Other gauges double: Other gauges includes meter gauge – 1,000 mm and narrow gauge – 762 mm and 610 mm Double line track in which each track is designated to allow train travel in each direction  Other gauges single with distance stone: Movement of trains in both direction on a single track  Metalled road: Asphalt or pitched road, indicates a developed region  Unmetalled road: Kachcha road or a non-tarred road which indicates underdeveloped region, usually found in villages  Cart track: Path broader than pack track, made for bullock or camel carts; it connects one village to another, thus facilitating transport of village goods  Pack track: Path used by humans and animals to travel, usually found in hilly areas where vehicles cannot reach  Footpath: Path made by man in steep regions or forested areas due to the continuous use of a track to cross a certain area  Cuttings with tunnel: Cutting – construction through areas of low hills, where the rocks are cleared to create a route to make way for a road or railways  Tunnel: A passage for a road or railways through a hill  Bridge: An overhead structure to carry a road or railways across a river/ stream, marshy areas Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

4 Water Bodies  Perennial river: Has water throughout the year  Seasonal river: Dries up in summer, is indicative of seasonal rainfall  Waterfall: When a river falls from the edge of a cliff or steep slope, it forms a waterfall  Meanders: Movement of river in loops, indicative of the middle course of the river  Dry river bed with a perennial channel of water: During summers, the river dries off leaving a trickle of water channel flowing in it  Embankment: A wall, of earth or stone, constructed along a river, tank, or railway Line  River with rocks and island: River with rocks and island, signifies deposition by rivers  Broken ground: Gully erosion along banks of seasonal rivers, indicative of seasonal rainfall  Spring: A spring is a point or opening on Earth’s surface from where the underground water stored in acquifer seeps out and flows out on the surface  Tank: A hollow region which contains rainwater, indicative of rocky terrain  Diggi: A tank which is used for collection of water Diggi  Lined perennial well: A well with bricks and stones surrounding it; deep with water throughout the year. Well water that is salty or brackish in nature is shown with the word ‘Brackish’ written on its side in black.  Unlined perennial well: A well without a lining of bricks and stones; generally less deep and provides water to a smaller area  Dam: A wall-like structure built across a river for controlling the water flow and behind which a reservoir is formed to store water for later use. Weirs are low dams.  Aqueduct: An open channel raised on pillars to carry water over valleys or mountain regions, under the influence of gravity  Canal: A channel which carries water from a river to fields for irrigation or is used for navigation  Overhead tank: A tank for storing water raised above the ground with help of stands or pillars. The water is pumped into it by high powered motors and distributed from it to nearby areas.  Causeway: A raised metalled road built across a minor stream or swampy region or inundated by shallow levels of water during high tides  Siphon: A tube immersed in the water of an aqueduct at a higher level to bring the water to the fields at a lower level Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

5  Sluice: A water channel with a gate at its head to control the water. When the gate is opened, water flows into the aqueduct or canal. Vegetation  Plantain: Cultivation of banana-like fruits which are generally cooked before eating  Scrub: A region of thorny bushes, low trees, and shrubs, indicative of scanty rainfall in a region  Open scrub: A region of thorny bushes, low trees, and shrubs, indicative of scanty rainfall in a region  Palms: A variety of trees belonging to the Arecaceae family. They grow in hot climate areas.  Reserved forest: A forest which is a government property and local people are prohibited to use for hunting and grazing, unless a forest officer specially allows  Protected forest: A forest in which the government has proprietary rights and the power to issue rules regarding the use of such forests. Here, permission can be given to the communities living in the periphery to use the forest for meeting their needs of livelihood like grazing of animals or hunting.  Surveyed tree: The tree used for survey purpose. This tree is not allowed to be cut Settlement  Permanent hut: A house where people live continuously  Temporary hut: A house where people live for a few months, e.g. a house in a hilly area  Deserted towns/villages: A settlement that has been abandoned  Inhabited settlement: A settlement in which people are living  Antiquities: Ancient monuments  Temple: A place of worship  Chhatri: A dome-shaped structure, which is held up by a series of ornamental columns or pillars  Church: A place of worship  Mosque: A place of worship  Post office: An office responsible for postal services  Rest House or Inspection Bungalow: A house in which Government employees are entitled to stay Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

6  Circuit House: A house in which Government employees of high posts are entitled to stay  Police station: The office of the local police force  Police chauki: A police post with two or three policemen, under a police station  Power lines: For transmission of power, it may be with pylons surveyed or with poles unsurveyed  Hospital: A hospital providing medical help to sick and injured people  Dispensary: A health care unit that is small and has lesser amenities  Veterinary: Hospital/ Dispensary: A hospital/dispensary for animals Representation of Heights above Sea Level  Contours: Imaginary lines joining places having the same height above the sea level  Spot height: The spot is ‘x’ m above sea level. When it is approximate, it is written in italics and in smaller font  Trigonometrical station / Triangulated height: The place is ‘x’ m above sea level.  Benchmark: The benchmark is ‘x’ m above sea level. Other Features  Form lines: Sometimes the relief of an area is highly inaccessible for survey. So, for such areas survey is not possible and through eye estimation, the relief feature is shown in discontinuous brown coloured lines called form lines. They have no value assigned to them  Forest boundary: The outer limits of the protected and reserved forests  Mine: An excavation made into the earth to extract minerals  Sand dune (shifting): Mounds of hills and sand deposited by wind  Sheet rock: A continuous stretch of hard horizontal embedded rock structure which has been exposed to the surface by the removal of the overlying soil cover and levelled into a polished surface by agents of erosion  Rocky knob: A rounded isolated hill or a mountain  Rock outcrop: A piece of bedrock protruding on the surface since overlying materials are blown away  Kiln: A large outdoor furnace used for baking of bricks  Lime kiln: A big oven used for calcination of limestone or calcium carbonate. Limestone under intense heat in the kiln changes into calcium oxide (quicklime). Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

7  Stony waste: A barren land covered with broken rocks and pebbles, from where fine particles are blown away  Quarry: A place where rocks are excavated and crushed into smaller pieces to be used for construction and other industries  Depression: An area which is hollowed or lowered by the deflation actions of winds  Fire line: A gap or pathway made clear in forests and devoid of vegetation to stop the spread of forest fires  Tourist site: Place of interest to Tourists Colours Used in Topographic Maps Black – names of all settlements; lines of latitude and longitude; seasonal waterbodies such as rivers, streams, and tanks; broken ground; railway lines; survey trees with their numbers, earthwork dams, embankments, temples, chhatris, churches, mosques, tombs, graves, boundaries, rest houses, circuit houses Blue – features related to perennial waterbodies, aqueducts, lined and unlined perennial wells, overhead tanks, veterinary Hospitals/dispensaries, tourist sites Green – forests, grasslands, orchards, scattered trees, palms, palmyras, plantations White – uncultivated land Yellow – cultivated land Brown – sand dunes, contours Red – eastings and northings; metalled roads, unmetalled roads, pack tracks, cart tracks, footpaths; masonary dams, settlements, hospitals, dispensaries Representation of Relief and Heights Contours: They are imaginary lines joining places having the same height on ground above mean sea level. Vertical interval (VI): Vertical interval is the vertical distance between two successive contours. The VI of a map remains constant throughout the map. Horizontal equivalent (HE): Horizontal equivalent is the horizontal distance between two successive contours. If the HE is less, then it suggests a steep slope. Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

8 When the HE is more, the slope is gentle. Slope is calculated by the ratio between VI and HE. Index contours: Every fifth contour, in multiples of hundred, is made bold and thick to help in easy reading of contour value. These thick bold lines are called index contours. Contour interval: The vertical distance between two successive contours is called as contour interval. It is the interval at which contours are drawn. Types of Slopes: The spacing between contours indicates the types of slopes. Contours representing a gentle slope are far apart, whereas contours representing a steep slope are close together. Some slopes are a combination of steep and gentle slopes. A concave slope is gentle in the lower part and steeper in the higher part. Therefore, contours are far apart in the lower part but closer in the higher part. On the other hand, a convex slope is steep in the lower part and gentle in the higher part. So contours are closer in the lower part but farther away in the higher part. A sudden steep rise in the land is called a cliff. In this, contours merge with each other. An irregular slope does not conform to any pattern. Conical hill: A conical hill is like a cone with a broad base with sides that slope equally and a narrow peak or summit. On a map, it is represented by equidistant circular contours with values (representing the height) increasing towards the centre. The highest point, i.e. the peak is a point in the centre of the contour diagram and can be represented by a spot height, i.e. a dot and a number. Plateau: A plateau is an elevated upland with a flat surface and steep sides. The contours representing a plateau are closely packed on the sides and are generally absent in the centre. Ridge: A ridge is a long narrow highland with more than one summit. The sides of the ridge have a steep slope. On a map, a ridge is depicted by long, closely spaced contours with more than one summit in the centre. Saddle: A saddle is a broad, flat, gently sloping area between two summits of a ridge. It resembles the saddle of a horse and is hence so called. Col: It is associated with high mountains. A col is the lowest point between two peaks of a mountain and is generally found at high altitudes. It is lower than a saddle. It is a French word meaning ‘neck’. Cols are generally not suitable passes but can be used by climbers to cross mountains. They are generally associated with glacial features like an arête ridge. Escarpment: It is the long, extensive, steep side of a hill, plateau, or ridge. The contours are close to each other but do not touch each other. The scarp (steep) slope is called the escarpment. A hill with a steep slope on one side and a gentle slope on the other side is called cuestas. Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps

9 Valley: A valley is an extensive lowland found between mountains. Valleys are created by glacial or river erosion and have various morphological characteristics. They are represented as V-shaped contours with the apex of the ‘V’ turned towards the higher ground. The innermost contour has the lowest value while the outermost one has the highest value. A deep V-shaped valley with steep sides has contours that are more closely placed than does a gentle valley. Spur: A spur is a highland or ridge projecting out from the side of a hill or mountain towards the lowland and valley. A spur is represented by V-shaped contours with the apex pointing towards the lower ground. Knoll: A knoll is a low, isolated hill, mostly roundish in shape. Water divide/ Watershed): A water divide is a highland, mountain, ridge, or an upland that separates two river basins. Water flowing on one side of the water divide forms a complete river system that is entirely different from that flowing on the other side of the divide. The two river systems flow in different directions and do not meet. Spot Height: It indicates the actual height of a spot above sea level. Unlike contours, it can only denote the height of a place above sea level and does not provide any information regarding relief features. It is denoted by a dot followed by a number, which represents the height of the spot above sea level. Benchmark Benchmarks are etched on walls, pillars, and stones. A benchmark represents the height of a place above sea level. It is denoted by BM followed by a number which is the height above sea level. The difference between spot height and benchmark is that benchmark includes the height above sea level of the point and also added to it is the height at which the mark is written while spot height only denotes the height of the ground above sea level. Trigonometrical Station / Triangulated Height The heights of these points are determined by triangulation method. A trigonometrical station / triangulated height is denoted by a triangle followed by a number which represents its height above sea level. Relative Height It is the height of a feature with respect to the surrounding and not from sea level. A system of r is used to denote relative heights and relative depths. For example, a relative height of 8r represents an approximate height (in metres) between the top and bottom of a steep slope. A r in blue near a lined perennial well signifies its relative depth. Waterfall is formed when water tumbles down from a height. It is denoted by the word ‘Falls’ followed by a height. The word Falls 15 m in the map shown in Fig. 58 means the height of the waterfall is 15 m. Grade 10 (Geography) Mrs. Savita Kukreti Topo Maps