A sheet of paper is spread on a table in an office. It is a Survey of India topographical sheet numbered G43S7, and it covers the country between 24° 15’ N and 24° 30’ N, on the border of Rajasthan and Gujarat. Nobody at the table has ever stood on that ground. Yet within an hour they can say a great deal about it. They can say where the land rises and where it flattens, because the brown contour lines crowd together in one corner and thin out across the rest. They can say where people have chosen to live, because settlements are printed in Chinese vermilion and cluster in the lower ground. They can say where crops are grown, because a yellow wash lies over the fields. They can say which rivers carry water all year and which are dry sand for nine months, because the map marks causeways where a bridge was never needed. None of this is written on the sheet in words. It is all carried in lines, colours and symbols, and a reader who knows the code can lift it out. That code is what this chapter teaches.
Q1. How can a map tell you where people are likely to live, when it shows no people at all? Q2. What does the spacing of contour lines tell you about the slope of the land? Q3. Why have so many causeways been built across the rivers in this region? Q4. How can the climate of a place be worked out from a topo-sheet that gives no rainfall figures? Every one of these questions is answered by reading a sheet correctly, and this chapter will show you how.
4.1 Map Reading
Map reading means describing the physical and the cultural features shown on a map, and then working out how those features are related to one another. A topographical map, usually called a topo-sheet, is a detailed map of a small area drawn to a large scale, showing both the shape of the land and everything people have built on it.
Reading such a sheet is really two acts, done in order. First you identify the physical features — relief, drainage and vegetation. Then you interpret: you ask how those physical features have shaped the cultural or man-made features around them. Relief is simply the shape of the land surface, its highs and lows, and on a topo-sheet it is carried by contour lines. A contour is a line joining all the points that stand at the same height above sea level.
The order matters, because it follows the order of events on the ground. The hills, the rivers and the forests were there before the villages, the fields and the roads, and they set the limits within which people made their choices.
What The Sheet Shows
A topo-sheet shows a wide range of natural features. Mountains, plateaus, plains, rivers, streams, broken grounds, unlined wells, cliffs, waterfalls and valleys all appear, and their height and shape are conveyed by contours and the heights printed beside them.
It shows man-made features just as fully, but in a different way. Quarries, houses, temples, mosques, churches, post-offices, police stations, artificial lakes, metalled and unmetalled roads, embankments, tunnels and ports are marked by conventional symbols — agreed signs that stand for a real object, so that a small mark on paper can carry a building or a road.
The difference between the two is worth holding on to. Natural features are the work of processes such as running water, weathering and deposition, and their shape is drawn mainly by contours and by the blue and green of water and forest; man-made features are the work of people, and they are drawn mainly by symbols listed in the index at the bottom of the sheet. What links them is that the first group largely explains the second, and that link is what interpretation is for.
The sequence below sets out the order in which a sheet is read.
4.2 Primary Information Or Marginal Information
Most of the information about a map is not printed inside the map at all. It is given on the margins of the topo-sheet, which is why it is called the marginal information, or the primary information. Before reading a single contour, a careful reader reads the margins.
The margin of a topo-sheet carries the following: (a) The number of the sheet, such as G43S7 or G43S10, gives an idea of which part of India is being depicted by the map. (b) The latitudinal and longitudinal extent is printed along the edges. In a topographical map of 4 degree, four lines of latitude and longitude are drawn, the number of latitudes goes on decreasing with the increase in scale of the topo map, and on a degree map only two lines of latitude are drawn. (c) Eastings and northings are two-figure numbers printed at intervals of 1 km along the north and east edges of every map, and the grid they form enables us to: (i) find the exact location of a place; and (ii) estimate the area of a region. (d) The scale of the map is given below the map, for example 1:5,00,000, and scale is dealt with in detail in Chapter 3. (e) The contour interval is the vertical distance between two consecutive contours on a map, and it depends on the scale of the map, the amount of vertical height involved and the purpose for which the map is to be used. (f) The direction of true north and magnetic north must be shown, because a north–south line has to be indicated on a map; most large-scale maps print two arrows starting from a common point on the margin, one for true north and the other for magnetic north. (g) The legend, or character-sheet, is the list of commonly used conventional signs and symbols given at the bottom of the topo-sheet. (h) The year of survey and publication is indicated at the bottom of the topo-sheet.
Each of these deserves a second look, because each one changes how the rest of the sheet is read.
The Grid Of Eastings And Northings
The vertical lines running up the sheet are eastings, and their numbers increase as you move east. The horizontal lines running across are northings, and their numbers increase as you move north. Because the lines are drawn at intervals of 1 km, every square they enclose is one kilometre by one kilometre on the ground.
That single fact does the work of both uses listed above. A place can be pinned down by naming the square it falls in, and an area can be estimated by counting how many squares it covers, since each full square is a known amount of ground.
What The Scale Fixes
A scale written as 1:5,00,000 is a representative fraction. It means that one unit of length on the map stands for 5,00,000 of the same units on the ground:
\[1 \text{ unit on the map} = 5{,}00{,}000 \text{ units on the ground}\]
Here ‘unit’ can be a centimetre, an inch or anything else, as long as the same unit is used on both sides. The scale also decides how much detail can be shown. A large-scale map covers a small piece of ground in fine detail, which is why the number of lines of latitude drawn on a sheet goes down as the scale goes up — there is simply less ground on the paper.
Two Norths, Not One
The two arrows on the margin do not point the same way, and the difference is real. True north is the direction of the geographic North Pole, the fixed point about which the earth turns, and it is the north used to draw the map. Magnetic north is the direction in which a compass needle settles, which is governed by the earth’s magnetic field and does not sit exactly at the pole. A reader in the field lines the map up with the compass, so the sheet must state how far apart the two directions lie.
The margin also fixes how much trust the sheet has earned. The year of survey and publication tells you when the ground was last looked at, and the legend tells you what every mark on the sheet is agreed to mean.
Fig. 4.A2 The margin gives the sheet number, the extent in latitude and longitude, the grid interval, the scale, the contour interval, the two norths, the legend and the year. Read together, they tell you where you are and how finely the ground has been drawn. What they do not tell you is what has changed on the ground since the year of survey.
4.3 Relief Features
The relief features on a topo-sheet include highlands — mountains, hills and plateaus — and lowlands. They are told apart by the comparative density of the contour lines. Contours drawn close together mean that a lot of height is being climbed over a short distance, so the slope is steep; contours drawn far apart mean the same height is spread over a long distance, so the slope is gentle.
What a reader looks for depends on which kind of country is on the sheet. (a) In highland areas like hills, note the alignment of the ranges and the steepness of the slopes. Locate the peaks and the hill tops, mark the gaps between two hills, and determine whether a gap is a pass or a saddle; then find the average height of the region, and locate the maximum heights with a grid reference. (b) In highland areas like the plateau, find out the nature of the surface — whether it is a rolling upland or a dissected plateau — and find out the rock-types available. (c) In lowlands, find out the direction and the gradient of the slope. Look for the important rivers, their tributaries and their course, and note the soil-type.
Three of those words need pinning down. A saddle is the low dip along a ridge between two summits, and a pass is such a dip that is low enough and open enough to be used as a route across the highland. Gradient is the rate at which land rises or falls over a given distance, so a steep gradient and crowded contours are the same fact written two ways. A rolling upland has a gently waving surface, while a dissected plateau has been cut into by streams until it is broken up into separate flat-topped blocks.
Drainage Pattern
Drainage pattern refers to the pattern formed by a river and its tributaries as they drain an area. The pattern is not accidental: water takes the easiest line available to it, so the shape it settles into records the topography and the rock structure of the area beneath. This is why the drainage pattern in hills, plateaus and lowlands is different.
Three patterns are read off the sheet. (a) A dendritic pattern, in which tributaries join the main river like the branches of a tree, would indicate soft surface-rock material, because water can cut freely in any direction when the rock offers no resistance. (b) A trellised pattern, in which tributaries join the main stream at sharp angles in a rectangular arrangement, indicates the presence of limestone, where the streams are steered along lines of weakness in the rock. (c) A radial pattern indicates mountains, as it develops around a central elevated point from where streams radiate outwards in all directions.
Vegetation And Climate
Natural vegetation provides an indication of the climate, the soil, the land use and the occupations of an area, because plants grow only where the water, warmth and soil allow them to. Deciduous forests are the most widespread natural vegetation found on hills in India.
The sheet can therefore be read for far more than trees. (a) Absence of vegetation indicates erosion of land, since a stripped surface holds neither soil nor roots. (b) Scattered trees, found on lowland areas, indicate that agriculture is the occupation of the people in these areas, because the trees have been cleared to make room for fields. (c) Scattered scrub land and stony waste indicate desert conditions with poor soil, suitable for rearing goats, sheep, camels and horses rather than for crops. (d) A region of heavy rainfall is shown by ‘Dense forest’, or jungle, written on the map.
Bare Land On The Sheet Rainfall strips an unprotected slope → topsoil is carried away → roots find nothing to hold in → plants fail and the green wash disappears from the sheet → the map now shows land that cannot be cultivated, and the bareness itself feeds further erosion.
Reading The Climate Off The Sheet
Topo-sheets do not provide any direct information about the climate of a place, such as rainfall, temperature and humidity. No sheet prints a rainfall figure. But the climate can be inferred from the latitudinal extent of the area covered by the topo-sheet and from the type of vegetation found there.
Latitude gives the first clue, because places nearer the equator receive the sun’s rays more directly through the year. The climate of a place at 10°N latitude would be warmer than the place at 35°N latitude.
Vegetation type gives the second clue. Rain forests are found in the heavy rainfall areas, where temperature is between 25°C and 27°C and average annual humidity exceeds 77 per cent. The presence of scanty growth of cactus, thorny bushes and grass suggests an arid and semi-arid climate instead.
Q4. How can the climate of a place be worked out from a topo-sheet that gives no rainfall figures?
A. From two things the sheet does print. Its latitude fixes how much heat the place receives, and the vegetation marked on it — dense forest, open scrub, cactus and thorny bush — records how much rain that vegetation has been living on.
The chart below gives the outline of the scheme of interpretation of a topographical map, and it holds together everything this chapter goes on to do.
4.4 Relationship Between Physical Features And Human Activities
Human activities such as land use, occupation, trade routes, trade centres, settlement and the pattern of population are directly controlled by the physical environment. People farm where the soil and water allow it, build where the ground is level enough, and travel where the land lets them pass.
This is what makes a topo-sheet so useful. From the sheet we can state the factors governing a particular activity, without ever having spoken to the people who live there. The physical features are printed, and the human ones sit beside them, so the reasons can be reconstructed.
In the Indian topo-sheets, the settlements are shown in Chinese vermilion colour, a bright orange-red that stands out against the browns and greens of the land. The distribution of settlements is greatly influenced by the relief, but it remains interrelated with other aspects of human geography, such as water supply, transport and the need for defence.
4.4.1 Relief Features And Land Use
Relief features are closely related to land use, because relief decides what can be done with a piece of ground before anybody decides anything at all.
Highland Areas
Highland areas such as mountains, plateaus and river valleys can be determined from the contour pattern alone. If there is a sufficient number of contours, they follow an irregular path and their value varies from 200 to 1000 metres, it is a plateau. In such an area, waterfalls, knolls, ridges, escarpments and undulating slopes can be found.
Those four words describe four shapes. A knoll is a small isolated rounded hill, shown by a tight ring of contours. A ridge is a long narrow strip of high ground with the land falling away on both sides. An escarpment is a steep face that ends a stretch of higher ground, so its contours crowd on one side and spread on the other.
If the contours are larger in number, are closer together and their value exceeds 1000 metres, it represents a mountainous area. It shows steep slopes, V-shaped valleys, gorges, waterfalls and watersheds. A gorge is a deep narrow valley with almost vertical sides, cut by a river working downwards faster than the sides can wear back, and a watershed is the high line of land separating two river basins, from which water runs off in opposite directions.
Deciduous forest or mixed forests might be found here. Most highland areas with steep slopes are unsuitable for agriculture and may be fit only for grazing, because soil cannot settle on a steep face and a plough cannot work it. Sometimes the flat top of plateaus is used for cultivation.
If there is no contour, or if the contours are very few and are spaced wide apart, the area represented is a plain. In such an area, the river valleys are broad and shallow, and the course of the river is meandering and braided. A river meanders when it swings in wide loops across a flat gradient, and it is braided when it splits into many shallow channels around the sand and gravel it has dropped.
Q2. What does the spacing of contour lines tell you about the slope of the land?
A. Contours crowded close together mean a large climb over a short distance, so the slope is steep. Contours far apart mean the same climb spread over a long distance, so the slope is gentle. Where there are almost none, the ground is a plain.
The evidence of land use is shown by various symbols on topographical maps, and these are worth learning by sight.
Table 4.1 Caption: Symbols used on a topographical map and the land use each one points to. | Symbol | Land use | |—|—| | Open Scrub | Sheep and goat rearing. | | Stony waste | Uncultivable land | | Sheet rocks | Uncultivable land | | Rock outcrop | Uncultivable land | | Yellow coloured area | Agriculture | | Tanks, canals, wells and tubewells, etc. | Agriculture | | Green coloured area | Orchard, forest, scrub etc. |
Table 4.1 The left column names what is printed on the sheet; the right column names what people do with that ground. Three separate symbols all mean uncultivable land, so bare rock has more than one look. What the table cannot tell you is how well the land is being used — a yellow wash marks a field, not a harvest, and says nothing about its yield.
Lowland Areas
Lowland areas can be identified from the distant spacing of contours. What they are used for depends on how the water behaves there. (a) Well-drained and undulating lowland areas support mixed farming, since the water neither stands nor runs off too fast. (b) A very flat lowland may be subject to seasonal flooding, and this can be confirmed by noting the presence of broken ground. (c) Broken ground indicates the presence of soft soil, which is heavily eroded and is found along the banks of seasonal rivers or streams; it is formed by alternating dry and wet periods which cause the soil to crack and break. (d) Intensive use of the land for agriculture is indicated by the presence of canals, tanks and tube wells, because a farmer only pays for irrigation where the land is worked hard. (e) The presence of dry streams, dry ponds and dry wells indicates an area of scanty rainfall, or an arid region where cultivation is not possible.
Rivers
A river tells you which part of its journey it is in, and that decides what the land beside it is worth. (a) In its upper course a river flows down steep slopes, so cultivation is not possible. (b) A meandering river would indicate a flat gradient, and the river plain would be suitable for agriculture. (c) The flood plains of rivers are most fertile and indicate intensive agriculture, because every flood leaves a fresh layer of fine material behind. (d) Settlements are generally found on either side of a river, or where irrigation is possible; irrigation is indicated by canals, perennial wells and similar symbols. (e) Many causeways on a map indicate a dry river and desert regions which receive only seasonal rainfall. A causeway is a low crossing laid on the bed itself, which can be driven over while the bed is dry and is simply submerged when water comes down.
Drainage Pattern
Drainage of an area refers to the study of the main rivers and their tributaries, their size, direction of flow, drainage basin, slope of the valley, and other water bodies like lakes, tanks, ponds and reservoirs. A drainage basin is the whole area from which one river system collects its water.
The study of the drainage pattern indicates the following: (a) A dendritic drainage pattern shows soft surface rock material suitable for agriculture. (b) A trellised pattern shows the presence of limestone, indicating the unsuitability of the area for agriculture. (c) A radial pattern of drainage is seen from high land regions where rivers radiate in all directions. (d) A disappearing stream would indicate dry conditions with sandy soil, which is unsuitable for agriculture, since the water sinks before it can be used. (e) The presence of perennial rivers with their tributaries, dams and canals indicates that it is an agricultural area, well-irrigated by rivers. (f) The presence of non-perennial rivers and streams shows that the region gets moderate to low rainfall; in such areas, man-made resources of irrigation like wells, canals and tanks are found. (g) In a limestone area, the streams may suddenly appear or disappear, because water travels underground through the rock for part of its course.
4.4.2 Settlements
A settlement is a group of human dwellings in urban or rural areas. Where these groups are thick, thin or missing altogether is not a matter of chance, and the sheet lets you check it. (a) Thickly settled areas are found: (i) over fertile plains; and (ii) on wide river valleys. (b) Thinly settled areas may be found: (i) over plateaus with poor agricultural land; (ii) in forests; (iii) on terraced mountain slopes; (iv) over flat hill tops; and (v) in deserts with poor vegetation. (c) Absence of settlements, or empty space, may be seen over: (i) marshes and swamps; (ii) inaccessible forest; (iii) steep mountain slopes; (iv) areas of possible flooding; and (v) sandy deserts.
Read down that list and one thread runs through it. People gather where there is level ground, water and workable soil together, thin out where one of the three is missing, and vanish where the ground is dangerous or cannot be reached at all.
Settlements Along A River Factors: fertile flood plain, water for irrigation from canals and perennial wells, level ground of the river plain, gentle gradient. The decisive one: water. Fertile soil is useless without a dependable supply, which is why settlements follow the banks and the canal lines rather than the best soil alone. Move it: give the area a perennial canal away from the river, and the settlements would spread to it.
4.4.2.1 Types Of Settlements
Settlements are also classified by the pattern they make on the ground. (a) In linear settlements, houses are usually stretched out along the local road, river, canal or railway line, so the settlement is long and narrow. Linear settlements are also known as ribbon-patterned settlements. (b) Dispersed or scattered settlements are the pattern of rural settlement in which most of the population lives in farms, houses and cottages scattered over a large area. This type of settlement is generally associated with regions of high land, poor soils and an abundance of available sources of water, and also with large farms and sparse population; these settlements are shown on the survey maps by red squares spread over a wide area. (c) In clustered settlements the houses stand together rather than apart, and these take two forms: (i) In radial settlements, houses are in a star-like cluster around a tank, lake, factory or similar central point. (ii) A nucleated settlement is a form of rural settlement in which farms and other buildings are clustered together, often around some central feature like a church or temple or police chowki.
Some of the factors which encourage nucleated or compact sites include the need for defence, the availability of water supply at particular locations, and the development of modern means of transport. Each of these pulls houses towards one point, while poor soil and scattered water sources push them apart — which is why a dispersed pattern and a clustered pattern can occur within a few kilometres of each other.
4.4.3 Occupations
Occupations have to be inferred from topo-sheets, as there are no symbols to show the occupations of people. Nobody’s job is printed anywhere. Sometimes certain names like ‘farms’ and ‘orchards’ provide some evidence of these occupations, and the rest has to be read from what the land carries.
Table 4.2 Caption: Occupations and the evidence on a topo-sheet from which each one is inferred. | Occupations | Evidences | |—|—| | (a) Forestry | Forest or Green Patch | | (b) Agriculture | Yellow Patch or orchards | | (c) Cattle-grazing or sheep rearing | Meadows or Scrub | | (d) Quarrying and mining | Mines and Quarries | | (e) Trade | Settlement near main roads, ports, rivers, etc. | | (f) Industrial Development | Factories and mines | | (g) Entertainment and Cultural development | Golf Courses, Parks, Rifle Ranges, etc. | | (h) Fishery | Coast, lakes, rivers, etc. |
Thus, the occupation of the people of an area can be inferred from the following: (i) topography of land; (ii) size of settlement; (iii) presence of quarries and mines; and (iv) communication network indicating trade; (v) water bodies.
Notice that every one of these is an inference, not a reading. The sheet shows a green patch; forestry is what we conclude from it. Two readers can look at the same scrub and disagree about whether goats are kept there, and neither can be settled from the paper alone.
4.4.4 Means Of Transport And Communication
Generally, every settlement is connected by a mode of transport like a foot path, cart-track, camel track, roadways, railways, waterways and airways. A topo-sheet depicts railways, including broad gauge and metre gauge, the two widths of track on which trains run. The roads are shown by means of symbols of cart-tracks, pack-tracks, metalled roads, unmetalled roads and footpaths with a bridge.
The differences between these roads are differences of surface, and therefore of what can travel on them and when.
Metalled roads are shown by solid parallel lines of colours ranging from red to orange and yellow, the colours showing relative importance. They are man-made hard-surfaced roads built with materials like concrete, asphalt or coal tar. Their presence is an indication of a developed area, because a hard surface is expensive and is laid only where enough traffic justifies it.
Unmetalled roads, shown by two parallel red dotted lines, represent ‘kutcha’ roads, which are made of soil or earth, and not a hard man-made surface like cement or tar as in the case of metalled roads. They carry traffic in the dry season and soften when it rains.
Cart tracks, often depicted as a continuous red line, indicate rough, unpaved roads or paths suitable for animal-drawn carts. Pack tracks, shown by broken lines or a series of dashes, usually in red colour, are rough unpaved paths in rural areas used by people or pack animals.
Footpaths are cleared passages for pedestrians, usually in forests and fields. They are indicated typically by a dashed or dotted line of green colour, and they are identified by considering the surrounding terrain, as they are usually found in valleys or through forests and fields.
Besides transportation, means of communication such as the post office and telephone lines are also shown on topo-sheets. A close network of means of transportation and communication represents economic prosperity of the area, because links of this kind are built and maintained where there is traffic, trade and money to sustain them.
4.5 Analysis Of Topo-Sheet No. G43S7
Everything in this chapter so far has been method. From here it is applied to one real sheet, and the sheet is read the way an examiner will expect it to be read — area first, then location, then relief, drainage, climate, vegetation, settlement, transport and finally the work people do.
4.5.1 Area
The area shown on the topo-sheet G43S7 lies in the western part of India, on the border of Rajasthan and Gujarat.
Because the grid lines on the sheet are drawn 1 km apart, the ground covered by any part of the sheet can be measured simply by counting squares.
WC 4.1 The situation: The area enclosed within the Eastings 25 to 35 and the Northings 91 to 95 on the extract of sheet G43S7 used in this chapter’s map work. The working: The total number of grid squares in the area enclosed is 40. The area of one grid square is \(1 \text{ km} \times 1 \text{ km} = 1 \text{ sq. km}\), where each side is the 1 km spacing between two grid lines. Therefore the area of 40 grid squares is \(40 \times 1 = 40 \text{ sq. km}\).
The number itself is easy; what matters is what it licenses. Once you know that a block of the sheet stands for 40 sq. km of real ground, you can say whether the two settlements inside it are neighbours or half a day apart, and whether the forest shaded there is a patch or a tract. Counting squares is how a map stops being a picture and becomes a measurement.
4.5.2 District
The sheet covers parts of two districts in two states: Banaskantha, in northern Gujarat, and Sirohi, in southern Rajasthan.
4.5.3 Location
Latitude — 24° 15’ N to 24° 30’ N Longitude — 72° 15’ E to 72° 30’ E
The sheet therefore covers a quarter of a degree of latitude and a quarter of a degree of longitude, which is a small window on the earth’s surface — and that is exactly why so much detail can be shown inside it.
4.5.4 Physical Features
Banaskantha district has a diverse landscape. There is hilly upland in the north-east with intermontane valleys, which are valleys lying between mountain ranges; the piedmont zone runs all along the periphery of the hilly area; and a gently sloping vast plain lies on the west and south west of the Banas river, with occasional undulations formed by sand dunes and mounds in the west. The western extension of this plain merges into the marshy area of the Rann of Kutch, the great salt marsh on Gujarat’s western edge.
Based on the relief, three distinct regions can be found on the topo-sheet.
Map 4.A2 The three shaded belts are relief regions, not districts, and they run roughly north-east to south-west — the same line the rivers take. The arrows give direction of flow, so height falls the same way. What the map cannot show is the height of any single point, or where the boundary between two belts actually lies on the ground; the change there is gradual, not a line.
4.5.4.1 The Eastern Rocky Highland
The Eastern Rocky Highland is a mountainous region having high relief and rugged topography. The hills in this region form the south-western extension of the Aravalli mountain chain and have a north-east to south-west extension, which is the direction in which all the rivers flow. Relief and drainage are therefore locked together here: the rivers run the way the hills lie, because that is the way the land falls.
The sheet shows the following in this region: (a) The hills in the north-eastern region rise up to 600 m, and the two hills mentioned on the topo-sheets are Jasor hill and Jawar hill. (b) Jasor hill is the second highest peak in Gujarat, is covered with thick forests, chiefly with bamboos, and is also known as Satpado as it contains seven ranges. (c) The eastern part of the Vadgam taluka is also hilly, and near Atal there is a hill of Pansval. (d) The hill slopes have many cliffs, which appear on the sheet where contours run together almost into a single line. (e) The hilly area is dissected by many streams which join the Banas river in the south and the Khariya nadi in the north. (f) At several places on the lower hill slopes, rock outcrops are found, where bare rock reaches the surface with no soil over it.
4.5.4.2 Lowlands
All along the periphery of the hilly area, there occurs a piedmont zone, that is, an area formed by debris deposited by shifting streams. Streams leaving the hills lose their steep gradient suddenly, cannot carry their load any further, and drop it in a spreading apron at the foot of the slope. In areas having an arid climate, such landforms are called bajada.
The sheet shows the following about this belt: (a) This area is located at elevations between 170 to 220 metre and slopes gently from east to west. (b) This area is dissected by rivers and has gullies or ravines along the river banks, which are the deep channels cut into soft soil by running water. (c) It is not completely flat, as it has an undulating surface, represented by small enclosed contours pointing to low hills, and these plains are dotted with mounds of stabilised sand dunes. (d) This area is endowed with extensive groundwater aquifers with ample water supply, which have been developed as a major source for irrigation. An aquifer is a layer of rock or sand below the surface that holds water and gives it up to a well.
4.5.4.3 The Western Saline Area
The third region is the driest of the three. (a) It lies to the west of the Balaram nadi and south of the Banas river. (b) The relative height of the sand hills varies from 9 to 14 m, as can be noticed from 9r, 10r, 12r, 14r and 15r marked on the topo-sheet. Relative height is the height of a feature above the ground immediately around it, not above sea level, and the small figures marked with an ‘r’ on the sheet give exactly that.
4.5.5 Drainage Pattern
The main rivers on this sheet are the Banas river, the Balaram nadi and the Khariya nadi. The word nadi is the local term for a river or stream, and nala for a smaller one.
The sheet shows the following about the drainage: (a) The Banas river flows into the swampland area of the Little Rann, north-east of the Gulf of Kutch, and it flows from north-east to south-west. (b) The Banas river has two right bank tributaries — the Sarod and Arado nadis — and a left bank tributary, the Balaram nadi. (c) The Banas river has a broad bed with its width varying from 1/4 km to over 1 km, but it has a narrow perennial water course, and its dry part fills during the rainy season. (d) The Sipu nadi is a tributary of the Banas river, which flows from north-east to south-west; the Varka nadi is a tributary of the Sipu nadi, which rises in the hilly region to the east and joins the Sipu nadi on its left bank; and the Hanva Nala is a tributary of the Varka nadi, has less sediment and is completely dry. (e) There are numerous streams besides the main rivers, which rise in the higher ground adjacent to the main rivers, and their courses show large tracts of broken ground, indicating soft soil easily eroded by water; most of these streams are seasonal and depend on the rains for water supply. (f) The sandy nature of the river beds indicates that a large volume of flow occurs in the rainy season, since only a strong flow could have carried and dropped that much sand.
A bed a kilometre wide with a thread of water in it is a record of two different rivers in the same channel — the small one that runs most of the year, and the large one that arrives with the monsoon and made the bed that size.
4.5.6 Climate And Vegetation
4.5.6.1 Climate
The climate of Banaskantha district is of the continental type. Places well inland lose the sea’s moderating effect, so their summers are hotter and their winters colder than a coastal place at the same latitude. In the hot summer season, the heat is fierce and the temperature rises up to 47°C, and it becomes more intense in the northern, north-western and western part.
The sheet’s area has the following climatic characteristics: (a) There are three climatic seasons — summer, hot and dry from March to June; monsoon, hot and wet from July to September; and winter, cool and dry from October to February. (b) The maximum temperature in summer is 47°C and the minimum temperature in winter is 0°C. (c) Since this region is located in the western part of India, it receives comparatively less rainfall than other parts of the country. (d) The annual rainfall is between 50 to 100 cm during the monsoon season. (e) Due to high temperature, excessive evaporation occurs, which gives rise to scrub and semi-desert vegetation.
A range from 47°C to 0°C in a single year is the signature of a continental climate, and it is also why the streams behave as they do — almost all the year’s water arrives in three months and the rest of the year takes it back by evaporation.
4.5.6.2 Vegetation
The vegetation of the area follows the rainfall closely. (a) The hilly region in the north is covered with mixed jungle, referred to in the topo-sheet as ‘Open Mixed Jungle’ and ‘Dense Mixed Jungle’, and the green colour indicates that the area has been categorised as forest. (b) The vegetation in these forests comprises short trees of the dry deciduous type and tall grasses, both of which can survive a long dry season. (c) In the hilly region, where the forests have been cleared, ‘Open Scrub’ is marked on the topo-sheet, indicating that the area receives only moderate rainfall.
4.5.7 Settlements
The pattern of settlement on this sheet can be explained almost entirely by water and level ground. (a) Almost all the settlements are located in the lowlands drained by rivers, because these areas have level ground and alluvial soil deposited by the rivers. (b) The hilly region and the sand hills have scattered settlements, because of the unfavourable topography and the lack of cultivated lands. (c) Except for Chitrasani, which is a rail and road centre, the other settlements are scattered in the lowland area and are either nucleated or dispersed in pattern, and many settlements are clustered around a temple.
Q1. How can a map tell you where people are likely to live, when it shows no people at all?
A. By showing what people need. On this sheet the settlements sit where the ground is level, the soil is alluvial and rivers supply water — and thin out on hills and sand, where none of the three is available.
4.5.8 Transport And Communication
Movement across this area is shaped by the same seasonal rivers. (a) Since the rivers are non-perennial and contain water only during the rainy season, a number of causeways have been built across the rivers and streams. (b) Most of the settlements have electricity, as is evident from the power lines drawn on the sheet.
Q3. Why have so many causeways been built across the rivers in this region?
A. Because the rivers here are non-perennial and hold water only in the rainy season. A causeway laid on the dry bed carries traffic for most of the year at a fraction of a bridge’s cost, and is simply left submerged for the few weeks the river runs.
Distances along these routes are measured off the sheet with its scale, and the measurement can then be turned into travelling time.
WC 4.2 The situation: A walk along the aqueduct on sheet G43S7, from the point whose six-figure grid reference is 261920 to the point whose six-figure grid reference is 274929, at a walking speed of 2 km/hr. An aqueduct is a channel built to carry water across a river or a low stretch of ground. The working: Map distance = 3.2 cm. Since the scale is 2 cm = 1 km, the actual distance is \(\dfrac{3.2}{2} = 1.6 \text{ km}\). Time taken \(= \dfrac{\text{distance}}{\text{speed}} = \dfrac{1.6 \text{ km}}{2 \text{ km/hr}} = 0.8 \text{ hrs}\), which is \(0.8 \times 60 = 48 \text{ minutes}\).
Notice what the two grid references did here. They fixed two points on the ground to within a hundred metres, and everything after that was arithmetic. This is the whole value of the grid and the scale together: a ruler laid on paper becomes a statement about how long a person will be walking in the sun.
4.5.9 Occupation Of The People
No occupation is printed on the sheet, so each of these is an inference drawn from what is printed. (a) Most of the people are likely to be engaged in agriculture, as many areas have yellow wash, which indicates cultivable land. (b) Rearing of sheep and goats may be prevalent in the hilly areas, where the ground carries scrub rather than crops. (c) People living in the villages adjoining the forest may be engaged in collecting forest products and firewood.
Thus, the main occupation of the people appears to be rain-fed agriculture, along with rearing of animals and gathering of forest produce. Rain-fed means the crop depends on the monsoon rather than on assured irrigation, which ties the year’s work to the same three wet months that fill the river beds.
4.6 Analysis Of Topo-Sheet No. G43S10
The second sheet lies immediately north of the first, and reading the two together shows how quickly the country changes. The same method is applied in the same order.
4.6.1 Area
This region lies in western India on the borders of Rajasthan and Gujarat, at the southern end of the Aravalli hills.
4.6.2 District
Sirohi and Banaskantha.
4.6.3 Location
Latitude — 24° 30’ North to 24° 45’ North Longitude — 72° 30’ East to 72° 45’ East
Compare these limits with those of sheet G43S7. This sheet begins where the other one ends in the north, so the two together cover half a degree of latitude of continuous ground.
4.6.4 Physical Features
This region is characterised by undulating topography in the west and hilly country in the northern, central and eastern parts of the district. Therefore, based on the relief features, two distinct regions can be found on the topo-sheet.
4.6.4.1 Hilly Region
The Abu-Sirohi range divides the district into two parts. Mt. Abu, at 1219 m, is an irregular plateau which is surrounded by several projecting peaks and ridges — so the highest ground here is not a single peak but a raised, uneven table with summits standing above it.
In the south-east corner of the topo-sheet lie the Aravalli hills, parallel ranges rising to a height of over 1400 m, and the Aravalli hills run from north-east to south-west. Two things follow from that alignment: the ranges lie parallel to one another, and the rivers that leave them are steered along the same north-east to south-west line.
4.6.4.2 Plains
The remaining portion of the topo-sheet is occupied by a vast semi-desert plain, marked by isolated hillocks and a chain of hills forming the eastern fringe of the Thar desert. These hillocks are the worn-down remains of higher ground, left standing while the land around them was lowered.
4.6.5 Drainage Pattern
4.6.5.1 Main River
The sheet shows the following about its rivers: (a) The Sipu nadi rises in the hills north of Abu and flows in a south-west direction. (b) The right bank tributaries of the Sipu nadi are the Sukli nadi, Undawala and Dior nadi. (c) The left bank tributaries of the Sipu nadi are the Devengan nadi, the Gogua nadi and another unnamed river flowing past Dolpura. (d) Two other rivers mentioned on the topo-sheet in the extreme southern part are the Jhambua Nadi and the Gomti Nadi, and there is another river named Tarepara Nadi in the Reserved Forest area, which is forest land protected by law. (e) The pattern of drainage in the hilly region is radial, and from Abu, the highest point of the region, the rivers radiate in all directions; in the plain region, the upper courses of rivers form a dendritic pattern. (f) There are no natural lakes in the district, and there are two artificial lakes named Nakhi Talao and Alwar Talao in Mt. Abu. Talao is the local word for a lake or tank.
4.6.6 Climate And Vegetation
The climate of this sheet’s area is described as follows: (a) The area has three climatic seasons — summer, hot and dry, from March to June; monsoon, hot and wet, from July to September; and winter, cool and dry, from October to February. (b) The maximum temperature in the summer season remains high, with the temperature rising up to 47°C, whereas the minimum temperature in December and January drops to 0°C. (c) The rainfall varies between 50 to 100 cm during the monsoon season. (d) The rainfall is high in the central part of the district around the hills, and decreases northwards and southwards from here.
The last point is worth holding on to, because the rainfall map of this small area is not uniform. The wettest ground is the highest ground, and the further you move from the hills in either direction, the less rain falls.
4.6.6.1 Vegetation
In the hilly region, dry deciduous forests with short trees are found. In the plain region, scrub and thorny bushes are found, where no agriculture is practised. The two belts of vegetation therefore follow the two belts of rainfall exactly, which is the general rule of this chapter working on a single sheet.
4.6.7 Settlements
The settlement pattern here has one exception that dominates the sheet. (a) Most of the settlements have either a nucleated or a dispersed settlement pattern. (b) Mt. Abu is a hill station situated at a high altitude which provides a pleasant climate. A hill station is a settlement developed at height for its cooler air, and the coolness comes from altitude alone — temperature falls as you climb, so a place high on the range is cooler than the plain a few kilometres away.
There are a number of tourist attractions at Mt. Abu, like Hanumanji ka Mandir, Sadka Devi Ka Mandir, Adhar (Arbuda) Devi ka Mandir, Raghunathji Mandir, Dilwara Jain Temples and Gautam Maharishi Mandir. Besides these, it has Jai Vilas Palace and the two artificial lakes, Nakhi Talao and Alwar Talao.
A Hill Station At Abu Factors: high altitude of 1219 m, pleasant climate, temples and palace, two artificial lakes, metalled road access. The decisive one: altitude, which is what makes the climate pleasant; everything else was built afterwards, for visitors the climate brought. Move it: lower the same site to the plain and it becomes another semi-desert settlement, temples and all.
The buildings and places at Abu are numbered on the topo-sheet rather than named on it, and this legend supplies the names.
Table 4.3 Caption: The legend of numbered references to Abu, to be used with topo-sheet G43S10. | No. | Reference | No. | Reference | |—|—|—|—| | 1. | Goagaon | 11. | Būndi Cottage | | 2. | Bīkāner House | 12. | Jaisalmer House | | 3. | Pālanpur House | 13. | Youth Hostel (Girls’) | | 4. | Rājputāna Club | 14. | Public Library | | 5. | Nun Rock | 15. | Trevor Oval | | 6. | Municipal Office | 16. | Youth Hostel (Boys’) | | 7. | Gora Chhapra | 17. | Kesar Bhawan | | 8. | Kāla Chhapra | 18. | Māchgaon | | 9. | Kumhārwāda | 19. | Sarūp Bhawan | | 10. | Toad Rock | 20. | Bharatpur House |
Table 4.3 Each number in the left column is printed on the sheet at Abu; the legend turns it into a name. Read down it and the mix is plain — a municipal office, a library, hostels, guest houses and named rocks, which is the mix of an administrative and tourist town. What it cannot tell you is where any of them stands, or which are still in use.
4.6.8 Transport And Communication
The area is well connected, and the sheet says so in several ways. (a) Metalled roads constitute the main mode of transport in this region. (b) National Highway 168 traverses the states of Rajasthan and Gujarat, and it covers a distance of 144 km between Thorad and Sirohi. (c) There are a number of causeways on the rivers and streams. (d) Anadra is an important settlement which has many facilities like a Police Chauki, Dispensary, Rest House and metalled road. (e) Dantrai, Pamera, Wahan, Bhatana, Dattani, Sirori, Sanwara, Revdar and Malgaon have a Post Office.
Distances along these roads are taken off the sheet in the same way as before.
WC 4.3 The situation: The distance along the metalled road from Hanumanji ka Mandir until it merges with another metalled road, measured on the extract of sheet G43S10 used in this chapter’s map work. The working: Map distance is 4.2 cm. Since the scale is 2 cm = 1 km, the actual distance is \(\dfrac{4.2}{2} = 2.1 \text{ km}\).
Two centimetres of paper is one kilometre of road, and every road distance on the sheet is found this way, whichever route is being followed. Note that this is distance along the road, not the direct distance between the two points — a road that bends around a hill will always measure longer than the straight line, and it is the road distance that decides how far a person actually travels.
4.6.9 Occupation Of The People
Once again the occupations are inferred, and the sheet supports several at once. (a) The main occupation of the people in the plains appears to be agriculture, as depicted by the yellow wash, which represents cultivable land. (b) The people in this region depend on the periodic rainfall for irrigation; besides this, there are tanks, wells and a canal in the north-east beginning from the reservoir in the grid square 2222. (c) The green colour in the hilly region indicates the presence of forests, with fairly dense mixed jungle and open mixed jungle present, and people here may be occupied in animal rearing, especially goat and sheep. (d) Some people may be employed in Post Offices, Police Chowkis, Hospitals and Rest Houses, while some others may be working in brick kilns, where clay is moulded and fired into bricks. (e) Besides these, the people living in settlements connected with National Highway 168 may be employed in roadside dhabas, petrol pumps and as motor mechanics.
The last point is the most interesting one on the sheet, because it is an occupation created by a line drawn across the map. A highway carries traffic that has to stop somewhere for fuel, food and repairs, and the settlements it passes through pick up work that has nothing to do with their soil or their rainfall.
4.7 Summary
- Map reading means describing the physical and cultural features shown on a map and working out how they are related. It is done in two steps — identify the physical features first, then interpret their effect on the man-made ones.
- A topographical map shows two families of features.
- Natural features such as mountains, plateaus, plains, rivers, streams, broken grounds, unlined wells, cliffs, waterfalls and valleys, carried mainly by contours and their heights.
- Man-made features such as quarries, houses, temples, post-offices, police stations, artificial lakes, roads, embankments, tunnels and ports, carried by conventional symbols.
- The information needed to read the sheet is printed on its margins, and is called the marginal or primary information.
- The sheet number tells which part of India is shown.
- The latitudinal and longitudinal extent is drawn along the edges, and the number of latitude lines falls as the scale rises.
- Eastings and northings are two-figure numbers at intervals of 1 km, and their grid lets us find an exact location and estimate an area.
- The scale, given below the map, fixes how much ground each unit of paper stands for.
- The contour interval is the vertical distance between two consecutive contours, and depends on the scale, the height involved and the purpose of the map.
- Two arrows from a common point give the direction of true north and magnetic north.
- The legend lists the conventional signs and symbols.
- The year of survey and publication is printed at the bottom.
- Relief is read from the comparative density of contour lines — crowded contours mean a steep slope, widely spaced contours a gentle one, and almost none a plain.
- Contours following an irregular path with values from 200 to 1000 metres indicate a plateau, with waterfalls, knolls, ridges, escarpments and undulating slopes.
- Contours closer together with values above 1000 metres indicate a mountainous area, with steep slopes, V-shaped valleys, gorges, waterfalls and watersheds.
- Steep highland is generally unsuitable for agriculture and fit only for grazing, though the flat tops of plateaus are sometimes cultivated.
- The drainage pattern records the rock and topography beneath it.
- A dendritic pattern indicates soft surface rock, suitable for agriculture.
- A trellised pattern indicates limestone, and unsuitability for agriculture.
- A radial pattern indicates high land, with rivers running outwards from a central point.
- Disappearing streams indicate sandy soil or limestone, where water sinks below the surface.
- Vegetation is read as evidence of climate, soil, land use and occupation, since topo-sheets give no direct information about rainfall, temperature or humidity.
- Climate is inferred from the latitudinal extent of the sheet and from the vegetation printed on it.
- Dense forest indicates heavy rainfall, open scrub moderate rainfall, and cactus and thorny bushes an arid or semi-arid climate.
- Human activities such as land use, occupation, trade and settlement are directly controlled by the physical environment, so the sheet allows the factors behind an activity to be stated. Settlements in Indian topo-sheets are printed in Chinese vermilion colour.
- Land use is read from symbols and from the water available.
- A yellow wash, tanks, canals, wells and tubewells indicate agriculture; open scrub indicates sheep and goat rearing; stony waste, sheet rocks and rock outcrops indicate uncultivable land; a green wash indicates orchard, forest or scrub.
- Broken ground indicates soft, heavily eroded soil along seasonal streams, formed by alternating dry and wet periods.
- Flood plains are the most fertile ground and indicate intensive agriculture, while many causeways indicate dry rivers and only seasonal rainfall.
- Settlements are grouped by where they occur and by the pattern they make.
- Thickly settled areas are found on fertile plains and wide river valleys; thinly settled areas on poor plateaus, forests, terraced slopes, hill tops and deserts; settlement is absent over marshes, inaccessible forest, steep slopes, flood-prone land and sandy deserts.
- Linear settlements stretch along a road, river, canal or railway line, and are also called ribbon-patterned settlements.
- Dispersed settlements scatter farms and cottages over a wide area, and appear as red squares spread widely on survey maps.
- Clustered settlements are of two kinds — radial, in a star around a tank, lake or factory, and nucleated, packed around a central feature such as a temple or police chowki.
- Occupations have to be inferred, since no symbol shows them, and the evidence comes from the topography, the size of settlement, the presence of quarries and mines, the communication network and the water bodies.
- Means of transport are distinguished by their symbols and their surfaces — metalled roads as solid parallel coloured lines, unmetalled ‘kutcha’ roads as two parallel red dotted lines, cart tracks as a continuous red line, pack tracks as red dashes, and footpaths as a green dashed line. A close network of transport and communication represents economic prosperity.
- Topo-sheet G43S7 covers the border of Rajasthan and Gujarat between 24° 15’ N and 24° 30’ N, in Banaskantha and Sirohi districts.
- It has three relief regions — the Eastern Rocky Highland rising to 600 m, the piedmont lowlands at 170 to 220 metre, and the western saline area of sand hills.
- Its rivers, the Banas, Balaram and Khariya, flow north-east to south-west, are largely seasonal, and are crossed by causeways.
- Its climate is continental, from 47°C in summer to 0°C in winter, with 50 to 100 cm of rain in the monsoon, and its main occupation is rain-fed agriculture with animal rearing and forest gathering.
- Topo-sheet G43S10 covers the ground immediately north, between 24° 30’ N and 24° 45’ N, at the southern end of the Aravalli hills.
- It has two relief regions — the hilly region of the Abu-Sirohi range with Mt. Abu at 1219 m and the Aravallis above 1400 m, and a semi-desert plain on the eastern fringe of the Thar desert.
- Its drainage is radial around Abu and dendritic on the plain, and its only lakes are artificial.
- Mt. Abu is a hill station whose pleasant climate comes from its altitude, and National Highway 168 brings occupations that the land itself would not support.
What This Chapter Cannot Tell You
A topo-sheet is a record of one survey on one date, and the year printed at the bottom is the limit of its truth. Roads are widened, wells run dry, forests are cleared and settlements grow, and none of that reaches the paper until the ground is surveyed again.
The sheet also stops at the edge of what can be drawn. It shows a field but not its yield, a settlement but not how many people live in it, a scrub patch but not whether goats are actually kept there. Every statement in this chapter about occupation is an inference from a symbol, and a reasonable inference can still be wrong.
Finally, scale conceals. At 1:50,000 a whole village fits into a small block of vermilion, and everything inside that block — which households have water, which lanes flood, who owns the land — is smoothed away. To learn any of that, someone has to go and look. ## 4.8 Check Your Concepts
- Table 4.2 lists the evidence from which each occupation is inferred. State the evidence you would look for on a topo-sheet to conclude that people are engaged in:
- forestry
- trade Then explain why finding that evidence still does not prove that the occupation is being followed.
- On sheet G43S7, almost all the settlements lie in the lowlands drained by rivers, while the hilly region and the sand hills carry only scattered settlements. Set out, step by step, the chain of physical reasons that produces this pattern, beginning with relief.
- Mt. Abu stands at 1219 m on sheet G43S10 and has developed as a hill station with temples, a palace and two artificial lakes. Which single factor is doing the real work in placing it there, and what would have to change for the same settlement to be an ordinary one?
- The year of survey and publication is printed on the margin of every topo-sheet. Explain why a reader must check it before using the sheet to describe an area today, and name two details on these sheets that could have changed since the survey.
- How can the climate of a place be inferred from the topo-sheet?
- What are the factors that affect settlements in an area?
4.9 Case-Based Questions
- Match the following physical features with the numbers marked on the extract of the topo-sheet:
- Dry river bed
- Saddle
- Steep slope
- Pass
- Gap
- Gully
- Knoll
- Hill
- Study the extract of the Survey of India Map Sheet No. G43S10, Map 3, and answer the following [Eastings 47-57, Northings 13-23]: what is the area in square km of the region enclosed within Eastings 52 to 55 and Northings 14 and 17?
- Study the same extract, Map 3, and give a reason for each of the following:
- broken ground along the banks of Sipu river.
- fairly dense scrub vegetation in the south-east part of the given map extract.
- Study the same extract, Map 3, and state what difference you notice in the drainage patterns between the streams in grid square 5315 and the streams in grid square 5119.