Chapter 2-Profiles Of Survey Maps 45/D7 and 45/D10PROFILE OF SURVEY MAP 45 D/7DESCRIPTION of the Area covered by Survey Sheet No. 45 D/7 (Gujarat and Rajasthan)District : Banas Kantha and SirohiLocation: Latitude 24 degree 15’ – 240 30’ NorthLongitude 720 15’ - 720 30’ East

This region lies in western India on the borders of Rajasthan and Gujarat at the southern end of the Aravalli Hills, immediately north-east of Sheet 45 D/10.

RELIEF : The area is mainly a plain except for:1. The east central region where the hills rise to almost 500 m.,2. The lower hills of the north-east corner.The slope of the land is from north-east to south-west in the northern half and east to west in the southern portion of the map. (indicated by flow of rivers)DRAINAGE1. The Banas river (not to be confused with the Banas river which is a tributary of the Chambal river to the north) flows into the swampland area of the Little Rann, north-east of the Gulf of Kutch. On this survey sheet it flows westward. It has two main right bank tributaries – Sarod and Arado Nadis and the numerous smaller streams like the one entering the river near Chekla (8192). The only left bank tributary is the Balaram Nadi from the south-east. The Banas river varies in width from 1/4km to over 1 km and has a narrow perennial water course. The dry portion fills in during the rainy seas.2. The Sipu Nadi is a tributary of the Banas river (the confluence) lying to the west of the area shown. It flows from north-east to south-west withits two main tributaries –Varka and Mahadeviyao Nadis joining the left bank. Both rise in the hilly region to the east.

In the region there are numerous other streams that join main rivers. They rise in the higher ground adjacent to the rivers and invariably their courses show large tracts of broken ground indicating soft soil easily eroded by water.

SOILS: Map symbols indicate desert conditions, a large part of the plain area being sandy. Soils are soft as shown by excessive erosion causing broken ground near water courses.

CLIM ATE: There are three climatic seasons:Summer hot and dry March to JuneMonsoon hot and wet July to SeptemberWinter cool and dry October to February

Maximum temperatures in summer are extremely high rising to over 470 C, while minimum temperatures in December/Jan often drops to almost 0 degree C. Because of its location in western India, it receives comparatively less rainfall than other parts of the country. The rainfall which is between 50 to 100 cm annually, falls during the monsoon season. High temperatures cause excessive evaporation. This gives rise to scrub and semi-desert vegetation.

NATURAL VEGETATION : Hill areas – dry deciduous forests of small treesPlains – scrub and throny trees where there is no agriculture.

IRRIGATION: This region is dependent on the periodic rainfall (Monsoon), tanks, wells foragriculture. There is only one canal in the north-east starting from the reservoir (2222) 

OCCUPATIONS: Agriculture, rearing of cattle, sheep, camels and horses.CROPS: Winter (Rabi) – Wheat, Barley, CottonMonsoons (Kharif) – Bajra, Jowar, Maize

COMMUNICATIONS: Except for the main line of the Western Railway and the road that runs across the south-east corner of the map through Chitrasani (8923), there are no other important communications. All 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 nucleated or dispersed in pattern.

PROFILE OF SURVEY MAP 45 D/10

DESCRIPTION of the Area covered by Survey Sheet No. 45 D/10 (Gujarat and Rajasthan)District : Banas Kantha and SirohiLocation: Latitude 24 degree 30’ – 240 45’ North

Longitude 720 30’ - 720 45’ East

This region lies in western India on the borders of Rajasthan and Gujarat at the southern end of the Aravalli Hills, immediately north-east of Sheet 45 D/7.

RELIEF : The sheet is divided into two distinct physical divisions:1. The Aravalli Hills rising to a height of over 1400 meters and occupying the south-east corner. The ranges are more or less parallel and run in a NE to SW directon.2. A large plain covers the remaining portion of the sheet. There are frequent outcrops of rocky ground, some of it rising to over 400 m (i.e. 100 m above the surrounding country side.)

DRAINAGE: In the hill area, the drainage is radial. Abu being the highest point of the area is the centre from which the rivers radiate. In the plains, the upper courses of the rivers are dendritic or fan shaped. The main stream Sipu Nadi rises in the hills north of Abu and flows in a south-west direction. It is periodic and seldom exceeds ½ km in width.

TRIBUTARIES: Right bank : Sukli Nadi, Unda Wala, Dior Nadi,Left bank: Sukli Nadi, unnamed river flowing past Dhavli, Devengan Nadi and Godua Nadi

NOTE:1. There are three Sukli Nadis in the survey sheet.2. Because this regions lies close to the desert areas where the soils tend to break up easily, the water courses are numerous and well defined for they are able to cut channels in the soft sandy soils. They are however periodic and rely on the rainy season for the water supply.

CLIM ATE: There are three climatic seasons:Summer hot and dry March to JuneMonsoon hot and wet July to SeptemberWinter cool and dry October to February

Maximum temperatures in summer are extremely high rising to over 470 C, while minimum temperatures in December/Jan often drops to almost 0 degree C. Because of its location in western India, it receives comparatively less rainfall than other parts of the country. The rainfall which is between 50 to 100 cm annually, falls during the monsoon season. High temperatures cause excessive evaporation. This gives rise to scrub and semi-desert vegetation.

NATURAL VEGETATION : Hill areas – dry deciduous forests of small treesPlains – scrub and throny trees where there is no agriculture.IRRIGATION: This region is dependent on the periodic rainfall (Monsoon), tanks, wells foragriculture. There is only one canal in the north-east starting from the reservoir (2222)OCCUPATIONS: Agriculture, rearing of cattle, sheep, camels and horses.CROPS: Winter (Rabi) – Wheat, Barley, CottonMonsoons (Kharif) – Bajra, Jowar, Maize

COMMUNICATIONS: Abu, in the hill area, is linked eastwards by two main roads, which run south-east to Abu Road and north-east to Oriya. In the south of this region the east-west main road links up at Karaunti (0700) with another main road which runs parallel to the foot-hills and connects a number of settlemtns. Many of the smaller settlements are linked by cart tracks.

SETTLEMENTS: Abu is a large hill resort, an administrative and an educational centre. In the plains, there are numerous settlements of much smaller size of which Sirori (2023) is the most important.

Chapter 3- Interpretation of Topographical MapsSTAGE 1 – TYPES OF MAPS

There are different types of maps. We will focus now on Topographical Maps.1. Topographical mapsIn order to do this, you must be able to:a.Interpret the shape of the ground from a map;b.Definition of relief; andc.Representation of height.

CONTOURS

•A contour is a line on a map joining two points of equal height, and is the standard method of showing relief on a topographical map.Contours are shown at regular vertical intervals. On a 1:50,000 map the interval is 10 m.

INTERPRETATION OF CONTOURS•The shape of the contours indicates the shape of the ground.When contours are further apart, the slope is gentle and when contours are close together the greater the drop.When contours are equal distance apart the slope is uniform:a.Contours are continuous. No matter how far they travel, they always return to where they started. Except for a cliff.b.When spacing of contours down a slope gets close together at the bottom, the slope is convex.c. When spacing is further apart, the slope is concave.

STAGE 3 – PLOTTING GRID REFERENCES•A grid is a rectangular square system of lines superimposed on a map,

within which any point can be located.Maps are normally printed so that north is on top.•North / South lines are called Eastings because the numbers increase as they go East.•East / West lines are called Northings because the numbers increase as they go North.

What are the 3 points in determining height? 1.bench marks;2.trig points; and3.spot height.

What are Eastings and Northings?1.Eastings run – move left to right; and

2.Northings run – bottom to top.What are the two most important things to remember when giving a grid?1.Easting value first; and2.never round up.

What is the purpose of a contour line? Joins points of equal heights.•A topographic map is a type of map characterized by large-scale detail and quantitative representation of relief, usually using contour lines in modern mapping, but historically using a variety of methods. Traditional definitions require a topographic map to show both natural and man-made features .•The Centre for Topographic Information provides this definition of a topographic map:"A topographic map is a detailed and accurate graphic representation of cultural and natural features on the ground."•According to Cartographer's Kraak and Ormeling,"Traditionally, the main division of maps is into topographic and thematic maps. Topographic maps supply a general image of the earth's surface: roads, rivers, buildings, often the nature of the vegetation, the relief and the names of the various mapped objects."•The study or discipline of topography, while interested in relief, is actually a much broader field of study which takes into account all natural and man made features of terrain.

Uses

•Topographic maps have multiple uses in the present day: any type of geographic planning or large-scale architecture; earth sciences and many other geographic disciplines; mining and other earth-based endeavours; and recreational uses such as hiking or, in particular, orienteering, which uses highly detailed maps in its standard requirements.

Map conventions•The various features shown on the map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads. These signs are usually explained in the margin of the map, or on a separately published characteristic sheet]•Topographic maps are also commonly called contour maps or topo maps.

In the United States, where the primary national series is organized by a strict 7.5 minute grid, they are often called topo quads or quadrangles.•Topographic maps conventionally show topography, or land contours, by means of contour lines. Contour lines are curves that connect contiguous points of the same altitude (isohypse). In other words, every point on the marked line of 100 m elevation is 100 m above mean sea level.

There are several rules to note when viewing topographic maps:•The rule of V's: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion. •The rule of O's: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called "hachures".•Spacing of contours: close contours indicate a steep slope; distant contours a shallow slope. Two or more contour lines merging indicates a cliff.•Of course, to determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is given at the bottom of the map.•These maps usually show not only the contours, but also any significantstreams or other bodies of water, forest cover, built-up areas or individual buildings (depending on scale), and other features and points of interest.•Today, topographic maps are prepared using photogrammetricinterpretation of aerial photography. Older topographic maps were prepared using traditional surveying instruments.•In most cases, contour intervals are consistent throughout a map. Sometimes dashed contour lines are present; these represent half the noted contour interval.

Understanding Topographical Maps

Understanding of surface depends on the ability to interpret topo maps. They-•Are based on accurate surveys.•Show a variety of landforms with carefully chosen symbols & signs.•Shows natural features like hills, valleys, waterfalls,•Also show man made features like roads, railways, buildings, bridges and canals.TOPOSHEETS ARE:-•Are prepared on a number of sheets since they are large scale maps.

•Each sheet gives the details of a part of the whole area.•When these joined together, they form a map of the whole area. 

INTERPRETATION OF TOPO MAPS AND SURVEY MAPSIT involves ability to follow the symbols portrayed in the map.•Understand the information given in pictorial and written form•Visualize the topography of the original area by interpreting the contour•Spot heights skillfully•Map reading is a practical skill.•Can be developed only by reading topo map very minutely and mentally analyzing the details with the help of conventional signs & symbols given in their conventional colours'•As the conventional symbols cannot cover all the graphical details, each topographical map sheet provides the necessary information in the margin for the users.1.Identification of topographical maps2.Reading the Grid reference3.Scale (R.F.)4.Representation of Relief by contours5.Directions6.Measuring distances and calculating distances7.Drainage8.Man-made and natural features9.Means of transport in relation to relief10.Land use and irrigation11.Settlements12. Inferring occupations13. Importance of colours and tints in topographical survey sheets14. Legend15. Glossary of conventional signs and symbols used in survey maps INFORMATION IN THE MARGINS

i)The number of the topo sheets: Topo sheets numbers can give an idea as

to which part of India is shown on the map. For example, topo sheet numbers 45D/7, 45D/10 and 45 F/3 show parts of Gujarat and Rajashthan.

•Knowing the number of toposheet can give us a clue about the general physical relief of the region and its climate which can be confirmed by

other information given in the map. 

•Eg- since all toposheets are from India, it may be inferred that all the reigons represented by those topo sheets would have a tropical monsoon climate, with seasonal rainfall.•Western Rajasthan – u may expect scanty rainfall- a fact which could be verified by the presence of dry river beds and disappearing streams.

•45D/7 shows a region of northern Guj, closer to the border of Rajasthan•45D/10 lies in the southern part of Rajasthan close to the border of Gujarat region•45F/3 lies in the western Rajasthan, near Jodhpur•53B/7 shows a region in Punjab, close to the border of Haryana.•56D/11 shows a region in north-east Karnataka.•64P/13 shows a region in north-east Orissa. 

ii) Latitudinal and Longitudinal extent: These indicate in whichpart of the Earth the area is located.•On a 4 degree topographical map, at least 4 lines of latitude and longitude can be seen. But as the scale of the topo map increases, the number of latitudes seen on the map decreases.

GRID REFERENCE

•A Grid is a set of lines used to find the exact location of places on a map.•The National Grid Reference is a system of rectangular co-ordinate.•The origin of the grid reference lies at a point in the south-west corner of the map.•Thus any place on the map can be located by starting its distance east or north of the origin of the grid reference.•Topo maps bear the national grid of squares drawn to the scale of 2 cm=1km with each square having a side measuring 1 km.•These are sheets most commonly used for various purposes and are of vital practical importance.•Vertical lines=Eastings since they are numbered from west to East•Horizontal lines = Northings - they are numbered from South to North•Net work of horizontal and vertical lines or the Eastings and Northings , is called the Grid. 

READING THE GRID REFERENCE

i)Origin is the South –West (SW) corner of the map. The reading on the map is always taken with reference to this origin.ii)Eastings are always read to the East of the origin.iii)Northings are always read to the North of the origin.•It is also identified as the Grid Reference

i)The readings are always taken to the right of the Eastings and to the North of the Northings.ii)While giving a grid reference, Eastings are always stated first, followed by Northings

Grid Reference of this picture is 2676

Four Figure Grid Reference:-•In four-figure grid reference, the first two figures are the eastings and the last two are the northings.Six Figure Grid Reference:•For greater accuracy, a third figure may be added to two-figure eastings and northings.i) Obtain the four figure reference by using first two digits of eastings and northings. ii)Then divide each kilometre into ten parts visually, both vertically & horizontally.iii) Mark the division of eastings and the division of the northing corresponding to the location.iv) The crossing point is the location of the reference point. 

SCALE•Refer to Survey Map No. 45D/7•In the map, 1:50,000 is the R.F. of the map, which means that one unit on the map represents 50,000 units on the ground.•For example, 1 cm on the map represents 50,000 cm on the ground.

(Scale of this toposheet is)Scale-2cm:1 km or1:50,000

•R.F. or Representative Fraction is the ratio between the distance on the map and the corresponding distance on the ground in the same unit.•Therefore, R.F. Distance on the map____________________________Distance on the ground

In the above map, R.F. = 1:50,000This map is referred to as 1:50,000map and its scale is 2 cm=1km. 

Representation of Relief on the Map and its Interpretation

•Earth’s surface – uneven – made up of hills, plains, plateaus, lowland which are varying in their elevation or heights from sea level.•The total terrain is also called physical landscape.•It can be represented on the maps through different methods, such as spot heights, contouring, etc.•Surveying is considered a part of science of map making.•Topographical maps are large-scale maps, they show a great deal of details about the relief.•In Topographical survey, actual survey is carried out and different methods are used to represent relief on the map as follows.i)Hachuringii)Hill shadingiii)Form lines

iv)Spot heightsv)Triangulation pointsvi)Bench markscontoursi)Hachuring: are short lines representing directions of a slope.- For steep slopes , they are drawn closer together than for the gentle slopes.- on flat grounds they can not be used at all.DISADVANTAGE: it gives no indication of the actual height and that both high plateau region and low plain are unshadedThe close hachuring of the high mountain regions tends to obscure other details of the map.II) HILL SHADING: A method of representing relief on a map by depicting the shadows that would be cast by high ground if light were shining from a certain direction.It can be defined as the addition of shadows to give the optical illusion of a third dimension, making hills stand out in relief. The shadows can be regarded as those which would be cast on an imaginary relief model of the ground when illuminated by parallel rays of light from a selected direction or directions.In this map, it is assumed to be from north west at an angle of 45 degree with the horizon.This method too gives a general idea of relief of the country by it does not give the actual height and that it is difficult to know whether a piece of land is sloping uphill or downhill.

THE DRAINAGE•The term drainage basin describes an area drained collectively by the network of a river along with its tributaries and sub-tributaries of various dimensions.•An area drained by a single river is called its Catchment Area.•A drainage system as seen in the topographical sheets usually develops a

pattern which is related to the general structure of its basin.

3 distinct patterns can be recognized 

1)Dendritic:

Dendritic drainage patterns are most common. They develop on a land surface where the underlying rock is of u

niform resistance to erosion. •Dendritic drainage systems are the most common form of drainage system. The term dendritic comes from the Greekword "dendron", meaning tree, due to the resemblance of the system to a tree.•In a dendritic system there is one main river (like the trunk of a tree), which was joined and formed by many smallertributary rivers. They develop where the river channel follows the slope of the terrain.•Dendritic systems form in V-shaped valleys; as a result, the rock types must be impervious and non-porous

2. TRELLIS 

Rectangular drainage patterns develop where linear zones of weakness, such as joints or faults cause the streams to cut down along the weak areas in the rock.

•Trellis systems form in areas of alternating geology, particularly chalk and clay. The main river (the consequent) flows straight down hill.•Subsequent streams develop perpendicular to the consequent along softer rock and erode it away, forming vales.•The consequent river then cuts through the escarpments of harder rock.•Obsequent streams flow down thedip slope of the escarpments to join the subsequent streams. 

3. RADIAL

•Radial drainage patterns develop surrounding areas of high topography where elevation drops from a central high area to surrounding low areas.

SIGNIFICANCE OF COLOURS IN TOPOSHEETSOn toposheets colours are used to show certain features. Each colour used on a map has significance.1. BLACK – All names, river banks, broken ground, dry streams, surveyed trees, heights and their numbering, railway lines, telephone and telegraph lines, lines of latitude and longitude.2. BLUE – Water features or water bodies that contain water.3. GREEN – All wooded and forested areas, orchards, scattered trees and scrubs.Note:- Prominent surveyed trees are shown in black. Surveyed trees have numbers on their trunks. They serve as landmarks and are not allowed to be cut.4. YELLOW – All cultivated areas are shown with a yellow wash.5. WHITE PATCHES – Uncultivable land6. BROWN – Contour lines, their numbering, form lines, and sand features such as sand hills and dunes.7. RED – Grid lines (eastings and northhings) and their numbering, roads, cart tracks, settlements, huts and buildings.

SETTLEMENTS1. On a topo map, all settlements are shown by symbols in RED colour.2. The size of the symbol and size and style of letters used give an idea of the size of the settlement.3. In the case of large cities, major roads are marked and named.4. Deserted village cities, temporarily occupied huts are also shown.

5. Places of worship, forts, water towers, burial grounds, police stations, post office, dak bungalow, circuit houses, etc. are indicated by suitable symbols.NOTE – Site is the land on which the settlement (village or town) is built.Dense settlements : Fertile plains and wide river valleys.· Sparse Settlements : forests, deserts, mountain slopes, plateaus and hill tops with poor vegetation·Absence of Settlements: Swamps, marsh land, sandy deserts, thick impenetrable forests, flood-prone areas, steep mountain slopes.

OCCUPATION AND MAP FEATURESAGRICULTURE – Level land with yellow wash; many wellsLUMBERING: ForestsCATTLE REARING – Pastures, meadows, grasslands, presence of road in highland region (sheep)FISHING – Plenty of riversMINING –Stony wastes, quaries, limestone bedsTRADE – Dense settlements near roadINDUSTRY – Large settlements near roads and railways, presence of raw materials, (like making, cement industry near limestone beds)TOURISM – hotels and innsAPPROXIMATE OR RELATIVE HEIGHT-is height is not taken from sea level but with respect to the surrounding area. It may be the height of a dam, bridge, sand dune or it can be the depth of a well, tank, hill or river canal, for example , 3r, 5r, 8r, etc.EXAMPLE:3r - the relative depth of perennial lined well in 3 metres●5r – the relative height of dry tank is 5 metres NOTE: CHECK THE SYMBOL – if it is tank, dam, bridge, embankment, etc then write the answer this way - the relative height of .............................. is ................meters.

Chapter 1 - Fundamentals of Maps

Fundamentals of Maps

THE SPHERICAL earth is best represented bya three-dimensional model of the earth, called a globe. All parts of the earth can be shown on it in their true shape, area and location along with correct cardinal directions and distances. But it cannot be made large enough to include detailed surface features. Hence, maps are much more useful tool than globes. A map is a two-dimensional diagrammatic representation of the whole or part of the earth and its surface features both natural and cultural at a given scale on a flat surface. However, all that is shown on the map is not drawn to scale. Only distances and areas are drawn to scale. We are familiar with the maps of the earth surface. But it is possible to draw maps of other planets and even the sky when pertinent data becomes available to us. We already have crude maps of the Mars and the Moon. A map gives a picture of one or several of the elements of the earth’s surface and being creation of humans, it gives only those details, which its maker intends to give. Instead of showing the details in their true or visible shape and size, it uses symbols that may or may not have similarities with the shape and size of objects represented. Maps have unique advantage of showing objects or patterns that may be intangible or invisible.For example, it may show political boundaries or rainfall pattern or crop distribution, which may not be marked on the ground. Thus, maps are basically symbolic drawing of visible as well as conceived locational and distributional patterns of whole or a part of the earth, the sky or any other heavenly body.

There are various ways by which the earth can be mapped:(a) by freehand sketches and diagrams;(b) by actual survey with the help of instruments like chain and tape, plane table, prismatic compass and theodolite etc.;(c) by photographs (ground photographs/aerial photographs);(d) by satellite and radar charts.With the availability of high-speed computers and Global Positioning System(GPS), digital mapping has emerged as an important tool of mapping.

The amount of information given in a map depends on:• Scale;• Projection;• Conventional signs and symbols;• Skill of the cartographer;• Method of map making; and• Requirement of the user.

Types of MapsMaps are of different types. Each map is unique in its design, content and construction and hence, a type by itself. Maps are broadly classified on two bases: scale and purpose or content .Based on the scale, there are two broad categories of maps:• Large Scale; and• Small Scale.

Large Scale : These maps represent small area of the earth on a large size of paper/cloth/plastic sheet with greater details. Examples of some of the large scale maps are:

(i) Cadastral Maps: The term cadastral is derived from French word cadastre’ meaning register of territorial property.The Cadastral maps are drawn to register the ownership of landed property by demarcating the boundaries of fields, buildings, etc. They are especially prepared by governments to realise land revenue and property taxes. The village maps of our country may be cited as an example of large scale maps. These maps are drawn on a verylarge scale, varying from 16 cm to a km to 32 cm to a km so as to fill in all possible details. The city maps may also be included in this category.

(ii) Topographical Maps: These maps are also prepared on a fairly large scale. They are based on precise surveys conducted by the Survey of India, Dehradun. They show general surface features in detail both natural and cultural. Principal topographic features depicted on these maps are relief, drainage, swamps and lakes, forests, villages, towns, means of transport and communication like roads and railways, and canals. Indian toposheets are generally prepared on the scale of 1:50,000.

Small Scale : These maps represent large areas on a small sheet of paper. They have fewer details. Examples of small scale maps are Atlas and Wall maps. The maps included in this book are also small scale maps. They give only a general picture of the area represented.

(i) Wall Maps: These maps are generally drawn boldly so that they can be seen from a distance. They are used in classrooms and cater to a larger audience. These maps broadly show very large areas like world as a whole, hemispheres, continents, and countries, states and districts. The scale is smaller than that of topographical maps but larger than atlas maps.(ii) Chorographical or Atlas Maps: The Atlas maps are drawn on a very small scale and give a highly generalised picture of the natural and cultural aspects such as the physical, climatic and economic conditions of different regions of the earth. Only a few atlases are prepared on a 1:1,000,000 scale like the ‘Times Atlas of the World’. The Registrar General of India brings out Census Atlas from time to time. National Atlas and Thematic Mapping Organisation (NATMO) is a well-known important organisation in our country that publishes all kinds of maps for various purposes depicting different parts of the country. Thematic maps are usually prepared on small scale highlighting specific themes such as relief, temperature, and political divisions. According to purpose or theme, maps could be broadly categorised as follow :

(a) Physical or Natural Maps(i) Orographic or relief maps represent features like mountains, plains, plateaus, drainage patterns, etc.(ii) Bathymetric maps show the depth of the oceans and seas. They are also known as charts.(iii) Geological maps represent rocks that form the crust of the earth, and their mode of occurrence and disposition.(iv) Climate maps show average condition of temperature, pressure wind and

precipitation of the world or part of it over a long period of time.(v) Natural vegetation maps show natural flora of an area or region.(vi) Soil map exhibits various types of soils covering the area.(vii) Weather maps denote the average condition of temperature, pressure, wind and precipitation over a short period, which may range from a day to a season.(viii) Astronomical maps show the position of stars and planets in the sky.

(b) Cultural MapsThese maps show the man-made features or human aspects.(i) Economic maps show distribution of important minerals, agricultural andindustrial products, and lines of transport and communication. They help inassessing economic development and potential of the area covered by the map.(ii) Political maps show boundaries between different countries and states within countries.(iii) Historical maps show the past events and facts.(iv) Social maps depict elements like language, caste, ethnic groups and religion.(v) Land utilisation maps exhibit the character of land use.

(c) Military MapsMaps used by Defence Services are called Military maps.(i) General maps on a scale of 1:1,000,000 or more depict only the broad topographical features. They are used by the Defence Services for general planning purposes.(ii) Maps having scales ranging from 1:1,000,000 to 1:500,000 are oftenclassified as strategic maps. These maps are used for planning concentratedmilitary action.(iii) Maps with a scale of 1:500,000 or less are called tactical maps. They serve as guides to small units like battalions and patrol units prior to and during movements anywhere near the front line.(iv) Photomap is an air photograph with strategic and tactical data superimposed on it.

All maps have some common elements. Location and distribution of various features and phenomena are depicted using distance, direction, and conventional signs and symbols.

Scale

Scale is the relationship between the distance on a map and the real distance on the earth’s surface. It may be expressed as a representative fraction (ratio), a line scale or a statement scale. It is an important element of a map because it gives relative picture of the ground reality. As you have read earlier, maps are generally classified into large scale and small scale. However, there is no universally accepted standard for classifying maps according to scale. What one considers to be large, may appear to be small or medium for others. The same person may consider a map to be of large scale for one purpose but of small scale for another purpose. As a result of this each specialised group of map users sets up its own standards for classification.As a matter of convention, maps having a scale 1:50,000 upto are classified as large scale maps, those falling between 1:50,000 and 1:1,000,000 as medium scale maps and those having scales above 1:1,000,000 are treated as small scale maps. The million sheets of the Survey of India and the National

Atlas of India are considered to be medium scale maps.

Methods of Expressing Scales 

The scales can be expressed in three ways:

1. Statement: The scale may be indicated in the form of a written statement. For example 1cm on the map represents 1 km on the ground. The scale is written as 1 cm to 1 km. This means that 1 cm on the map corresponds to 1 km on the ground. Although it is simple to express in words, it is difficult for those who are not familiar with the unit of measurement used. Besides, the scale will not be the same when the original map is reduced or enlarged. As such, this method is not very useful.

2. Representative Fraction (R.F.): It is also called as numerical scale. It is expressed as a ratio of map distance and ground distance. For example 1:1,000,000 means one unit of distance on the map corresponds to 1,000,000 units of distance on the ground. The advantage of R.F. is that it can be used universally irrespective of the local unit of measurement of distance. The mapcan be reduced or enlarged without changing the R.F.

3. Linear Scale or Graphical Scale: This scale is expressed as a horizontal or straight line. The base is calibrated to express visual equivalents of representative fraction or verbal scale. The bases are divided into a number of equal parts and are marked to show what these divisions represent on actual ground. The scale has the advantage that it remains true even after reduction or enlargement of the map. However, it is useful only to those who are familiar with the particular unit of measurement.

Distances on the map are smaller than the corresponding distances on actual ground. Scale is the means which enables us to reduce the whole or a part of the earth to a size which is not only convenient and handy but also logical and scientific. A general definition of scale is that it is a ratio between the distance on a map and the corresponding distance on the earth. For example if two points located 10 km apart are shown 1 cm apart on a map, then the scale of the map would be 1 cm to 10 km. It may also be converted into R.F as given below.Suppose, 1 cm = 10 KM

MAP DISTANCE_______________

GROUND DISTANCE

=

1 cm_____10 km

=1 cm____________10 X 10,000 cm

= 1: 1,000,000

(Note: 1 km has 100,000 cm.)

Methods of Measuring Linear Distance

Linear distance on maps are of two types:

(i) Straight lines like roads, railway line, and canals;(ii) Curved or Zigzag lines, showing streams, coastline etc.

(a) When the line is straight, the distance can be measured with the help of a divider.Open a pair of dividers and place one of its legs at one end of the straight distance and the other leg on the other end on the map. Then lift the divider and place it on the calibrated bar scale to get the distance on the ground

(b) When the route is zigzag, place one end of a thread at the starting point and carry the thread along the line. After completing the distance stretch the thread and measure the length. It will give approximate distance.It can also be measured with the help of a plain divider, as explained earlier, but the measurement will be less accurate. It can also be done with the help of a strip of paper.

(c) Rotameter is an instrument having a route measuring wheel. Distance between two points is measured by allowing the wheel of the rotameter to move along the route.

Direction

Direction has been defined as an imaginary straight line on the map or the ground showing the angular position of various maps with respect to a common base direction. The line pointing to the north is regarded as the zero direction or base direction line.A map must have the base directions represented on it to enable the user to locate different features with respect to each other. North, south, east and west are the four major directions. These are also called cardinal points. In between cardinal points one may have several intermediate directions.

A rough estimation of direction of the true north can be obtained by the Means of an ordinary watch. In the northern hemisphere if the watch is held in the horizontal position and turned until its hour hand points to the sun, the line that bisects the angle made by the hour hand with the line joining 12’O clock through the centre of the watch will point to the south. A similarexercise in the southern hemisphere will indicate the true north. This is also a crude method dependent upon the sun .

LegendsEvery map contains a legend or a key. It lists the features and the signs or symbols used in the map for showing these features. As you know various types of features or phenomena are represented on maps. They relate to both land and sea and are shown with the help of conventional signs and symbols. The signs and symbols include lines, icons, alphabets, shadings and colours. As a convention, specific colours show certain area features.

Review Questions1. Answer the following questions:(i) What is a map? What are its advantages?(ii) What is a scale? What purpose does it serve on a map?(iii) What are the small scale maps? Give two examples of small scale maps.(iv) What is a cadastral map?(v) What are cardinal points?2. Write short notes on:(i) Wall maps (ii) Linear Scale (iii) Base direction line.3. In how many ways the earth can be mapped and what factors determine the amount of information given in a map? Discuss.4. Describe various types of maps and their uses.5. What are the different ways of expressing scale? Explain the merits and limitations of each method giving suitable examples.

Land use Colour

Cultivated area YellowForests Dark greenGrasslands Light greenBuilt up area BrownWater features Blue

(Ponds, oceans, lakes, seas, rivers)You will know about conventional signs in detail in the chapter on study of topographic maps.

Chapter 4 - Interpretation of Topographical Maps (Part 2)

Man-made and Natural Features•Toposheets shows various details of an area- natural and man made features by means of conventional signs(legends), contours and pictorial diagrams in conventional colours.•Natural features – rivers, streams, sand features, trees, broken grounds, natural ponds, unlined wells, jungles, depresions (Dep), islands (in the exposed river beds), physical features like hills, waterfalls, spurs, river valleys and cliffs, shown by contours and their heights.•MAN made features – surveyed trees, queries, permanent huts, causeways, mines, metalled and unmetalled roads, pack tracts, cart tracts, artificial lakes with embankments, boundaries (national and international), post offices, police chowkies and inspection bungalows.

Means of Transport in Relation to Relief•Transport always depend on the type of relief and drainage•Eg. Very high altitudes, mountaineous areas-only roads and no railway tracks- difficult to build at such heights•On the map-roads are shown by means of symbols of cart tracks, pack tracts, metalled roads, unmetalled roads, footpaths with a bridge.•Main towns- well connected by metalled roads show economic devp of the area-is the indication of trade being carried on.•Hence town shows well developed.•Causeways are raised platforms across a dry stream.•During dry season when the stream dries up, people make a habit of crossing it.•Thus, a footway is formed.•Presence of many causeways shows that the area gets seasonal or scanty rainfall.

http://3.bp.blogspot.com/_zwaRuUhzrcM/SZb5xXBdiAI/AAAAAAAAAts/Xrm2F4W7kBY/s1600-h/Picture22.jpg

DIRECTIONS•Directions- important tool while reading topo map.•Directions are important for physical as well as urban features.•Physical features- directions of rivers, streams,•Urban cities from one another

DIRECTION-TO RIVER AND RIVER BANKS•Need to know which direction river flows.

•REMEMBER THESE STEPS:1.First look at the spot heights to determine the slope of the land2.To know which side/bank of the river a place is situated, one has to locate the source of the river. Having located the direction of the river, imagine yourself standing at the source of the river facing the main river facing the main river. Now to your right is right bank and to your left is the left bank.

Calculation of Area

•Area= Length x Breadth•In topo maps, each grid (square) 2cm X 2cm or 1 km to 1 km as per the scale 2 cm=1 km•Therefore , area of each square is4 sq cm (on the map)= 1 sq km (on the ground)In metres, this can be expressed asArea of each square (i.e. 4 sq cm) = 1000 X 1000or 1,000,000 sq m.

To calculate the area by grid square method:

If there are some incomplete squares, area can be calcualted as follows:-Note the number of completed squares-Squares covered half are taken as ½-Squares covering less than half area are taken as 1/3-Squares covering more than half of the area are taken as 2/3-All these estimated squares are added together and the sum is multiplied by the scale of the area given out above to obtain the desired area.

LAND USE

•IN topomap location of veg is closely related to relief.

•In the highlands, vegetation is shown –green colour along with contours in brown showing

elevation.•To show density of wooded area, different terms used:•Dense forest, open-mixed forest, open jungle, fairly-mixed jungle, dense-mixed jungle, mixed jungle, Reserved Forest (RF), Protected Forest (PF), fairly mixed jungle with bamboo, dense mixed jungle with bamboo.•The exterior boundaries of areas of Reserved or Protected forest are shown by green ribands .

THE PLAINS:-•Plains-mainly agriculture- cultivable land is shown in yellow colour

•White patch in plain shows bad land or rocky, uncultivable land.•In such land, following features are found-•Open scrub – scrub land where mostly sheep and goat rearing is practiced•Stony waste – the land which is mostly covered with rock boulders and stones and cultivation is not possible.

SHEET ROCKS:-•Sheet rocks – a region mostly covered with a sheet of rock.

•Rock outcrop – In such region subsoil is exposed and cultivation is not possible.•Broken ground – developed because of absence of natural vegetation on both the banks of the river. It is common in the desert area and in the areas of gully erosion.This is formed due to floods which occur during rainy season. Because of floods, the top soil is washed away developing into bad land which has loose soil and is uncultivable.

LOW LANDS:-•Plains which are situated at lower level are mostly characterized by a meandering river.•A disappearing stream shows a desert or limestone area•Presence of canal, wells, tube wells and tanks indicate use of land for agriculture by means of irrigation•A meandering river shows a flat area•Perennial lined wells indicate a higher water table and are shown by blue dots.

•Presence of dry streams, dry ponds, exposed river beds and broken land shown in black indicate an area with scanty rainfall or seasonal rainfall or a desert region.•Settlements are generally found on either side of river-wherever irrigation by canals or perennial lined wells is available

MEANS OF IRRIGATION

•Irrigation largely depends on relief and land use pattern of area (blue)•Hilly region- no cultivation is possible, hence there is no need for irrigation•On the flat lands which are coloured yellow, one can see blue, round spots which represent perennial lined wells. – therefore one can say that the main source of irrigation in such areas are wells and the occupation of people is farming.•Other means of irrigation are canals, ponds, artifical lakes withj embankments and river in case it is perennial.•Presence of dry streams and dry ponds with uncultivable lands shown in white indicates that the

rainfall in the area is scanty.•Presence of artificial man-made lake with embankment shows that water is being stored in off season and is used for irrigation through canals.

OCCUPATIONS

•Occupations have to be inferred from toposheets as there are no symbols to show the occupations of people.•Sometimes, certain names like ‘farms’, ‘orchards’ provide some evidence of these occupations.•The following list gives you some information about occupation of the people from a topo-sheet.

OCCUPATIONS EVIDENCESForestry, lumbering Forest or Green PatchAgriculture Yellow Patch or orchards with many wellsCattle-grazing or sheep rearing Meadows or Scrub, grasslands, meadows, pasturesQuarrying and mining Mines and Quarries, lime stone bedsTrade Settlement near main roads, ports, rivers, etc – densesettlementEntertainment & Cultural devpmnt Gold Courses, Parks, Rifle Ranges, etcIndustry Factory, mines, large settlements near roads andrailways, presence of raw materials (lime making andcement industry near limestone beds)Fishery Coast,l akes, rivers, etcTourism Hotels and Inns

•Thus, the occupation of the people of an area can be inferred from the following :•Topography of land•Size of settlement•Presence of quarry and mines•Communication network indicating trade

REMEMEMBER FEW POINTS:HACHURING: Hachuring are short lines representing directions of a slope. For steep slopes they are drawn closer together than for the gentle slopes. However on flat ground, they cannot be used.SPOT HEIGHTS: Spot heights are used to provide more information about land surfaces between the contours. These are represented by a number

preceded by a dot. for example ●340

TRIANGULATION POINTS: When the spot heights are accurately

surveyed , the dot is enclosed within a triangle and are called the triangulation points.

Interpreting Toposheets

Hello,See the features of this toposheet. Divide the toposheet into 4 quarters. Study the each quarter. For example North west corner (A), North East Corner (B), South West Corner(c) and South East Corner (D). For example what features do you see in the A Corner???First of all, you see river Sipu, a few nucleated settlements, yellow wash, open scrub, little bit of green forest on top of A corner, we can see some spot heights too. Can you see a cart track (red line)? We can also see perennial wells (blue). Did you spot stony waste (8596)? In the same way, go through the B corner and C corner and D corner. Make a mental picture of the toposheet with prominent symbols. After having a quick glance of thetoposheet, read the questions that are asked. You have 15 minutes to read the question paper. First read the other questions and then come to the toposheet which requires more time to read. Keep a pencil ready to mark few features.For the bigger view of the toposheet, click on top of the picture. Can you see R.F.? You can see at the bottom right. R.F. is 1:50,000. I have already explained to you how to write R.F. in the earlier lesson.

can you see the scale? You can see almost near the R.F. The scale is 2cm to 1 km. It means 2cm on the map is equal to the 1km on the ground. Good, i suppose u understood.

What's the contour interval of the toposheet? Check the contour interval near the scale. Contour interval of this toposheet is 20 metres.(usually it is 20 metres)

What else can you see? Ok, let's do the direction which i have explained to you earlier. Find out what is the directionof Rajkot lie from Gangudra? First of all, Rajkot is in grid square 8995 and gangudra is in grid square 8793. Imagine you are in Gangudra and you want to go to Rajkot from Gangudra? First of all, you hv to go up which is north and then you have to turn right, which is east direction.Therefore the comapass direction is north-east from Gangudra. Do you follow?

Where do you find the lowest part in the toposheet? The south west corner is the lowest part in the map. because two rivers flow towards south west whichis an indication of the slope. check the spot heights in the map. they are decreasing towards south west. Identify some spotheights in the map.

See the settlements on the map: What type of settlement do you find? Ofcourse, nuclear/compact/clustered. If you didnt understand, read the text book on settlements and come back to the blog.

What kind of rainfal this area gets? check the rivers-we can see broad sandy bed exposed, a thin water channel, (in blue) several cart tracks, and a pack track. This shows that the area gets seasonal rainfall.

Now let us see the occupation. Study the toposheet closely. I had told you about the occupations. Go through it again. Let us study the occupation of Bhadli (Jhat) - grid square 8596. What do you notice there? click the toposheet and check. its is A CORNER. There is a river, perennial wells (Blue dots), yellow patch(which means agriculture) and stony waste. Can you see them? From this we know that the occupation of the people of that area is cultivation and stone cutting or extraction of limestone. This is indicated by the presence of agricultural land ( in yellow colour), perennial wells and the presence of lime kilns.

It is a clustered settlement too.

Can you see the irrigation facilities or source of water? We can see the river which has narrow blue line which means it is perennial even though the river is seasonal. Then we also can see the perennial wells. So two perennial source of water is the River waters and well irrigation.

Let's study man made features - we can see few temples in the toposheets and permanent huts. I couldn't see any post office. As I have told you, my eyes are not very sharp. In the exam, they will ask one or two man-made features. So the man-made features are temples and permanent huts.

Now let's study the natural features - We can see rivers, trees, islands in the middle of the river, jungles, mines, pack tracks, cart tracks, lined wells, etc. You can see all these in this map. So, you select any two. The natural feature is river and forest. Sometime they will give a grid square and ask to you to mention one man-made feature and one natural feature. Go and locate that grid square and follow the points that I have told you.

Let us see the drainage pattern on the map. See the area around the town Gangudra.(Grid square 8793) See the drainage pattern around the area-dont see only in the grid square 8793. Go beyond that. The river or drainage pattern is Rectangular or Trellised. Can you see the shape of the river? Thin lines that join the main river. Read the text book regarding the drainage pattern (if you have not understood) There are three drainage patterns - Dendritic(Tree like or veins of a leaf) Trellis/Rectangle and Radial.

Let us study the river bed of Sipu- In what two ways does the river bed of Sipu convey that it flows through a region of seasonal rainfall? We did go through that earlier. Study the river. It has a broad sandy riverbed which is exposed. If you dont understand the sandy river bed, go to the text book and looks for the symbos of sandy bed. You will see it in my blog too. It also has a thin water channel in the middle of the river. We also see many cart and pack tracks passing the river. Therefore, the river doesn't have much water in the summer season and so the river dries up. Do you follow me? Since the river is dry, you see the sandy beds and cart and pack tracks passing the river. So the people can cross the river during summer. Therefore it is a seasonal river.(it means the river gets water only in the rainy season).

What are the conventional sighs near north east part of the toposheet near open mixed jungle? - check corner B - We find broken ground there. So what is broken land? Broken land gives rise to Bad land topography. These are generally found along the banks of a river. Broken ground is caused due to erosion during rain when the river is in flood. It usually heappens in the area where there is no vegetation/plants.

Some time a question comes on the comparision of two settlements. Now let us study the village Jigol (grid square 8590) and other villages. Jigol is better off than other settlements. It has good transport system in comparision with other villages. We can see many cart tracks leading into the village. Plus it has many lined wells for irrigation purposes.

In which quarter of the map extract do you find the lowest area to be? Divide the whole toposheet into 4 corners. We have done that in the beginning. Look for the spot heights in the toposheet. if you study the heights, you will find south west qurater of the map are decreasing

towards the south west. See also the river flowing. They flow towards the south west. So the south-west corner of the map exatract is the lowest region.

Hope you know how to find grid squares - 4 figure or 6 figure/digit grid reference. Find four digit grid square is easy but the problem begins when you have to find 6-digit grid reference. When you are asked to locate the 6-digit reference, rememeber these points. First find the square. Ok, let us locate a place using 6-figure grid reference of a temple in the north east of Odhava. Ok, let us see the 4-figure grid reference. It is in the grid square 8992. This is four figure grid reference. now we need 6-figure grid reference. After locating 4-figure grid reference, divide that square into 4 equal parts. First take a ruler and place it on the horizontal line of that grid square(. get the mid point. Then place the ruler on the vertical line and find the mid point and join these mid points. then u get the mid point of easting and northings. then u locate the spot in the grid square and if the spot is beoynd the mid point, then it wil be above 5. You can find the exact 6 figure grid reference by dividing grid squares into 10 blocks. Hold the scale vertical and horizontal on that grid square and join them. Now u get 10 X 10 equal squares. NOw you see where is the spot and give the grid reference.894925

Interpreting Toposheets -2

Let us look at this toposheet. Double click on this toposheet. You will see the enlarged topomap. Let us look at the Northern part of the toposheeet- see various features. Can you see QC,- What is it?According to the international system of location of a place the whole world has been divided into various squares. It starts frm the place where the equator and prime meridian meet and is named UA. Under the same fashion the whole world has been divided.......................... Thus the square is named QC.QC means that there is end of numbering of northing or easting i.e 0-99 on a toposheet it is written after every 100km. Here it is the end of northings.

Look at the town Panthawada- It has a police station (PS), Post Office (PO), well connected roads. a temple, perennial wells, etc.

Now let us to to the north-east of the map. What do you see over there? -OPEN SCRUB- What does it mean? It indicates desert or semidesert condition. The occupation in this area would be sheep or goat rearing.You will also see Lime Kiln- It is a furnace for baking limestone.Its presence shows the trade possibilities and the people working in it.

Let us study 6 figure grid reference. Look at the triangulated height of 224. Let us first find out four figure grid reference. Let us see the eastings first. We locate it in easting 82. Let us see the northings. It is in northing 94. So four figure grid reference of the triangulated height is 8294. Now how do you find four figure grid refernce. We have already found out the four figure grid refernce. (8294) Let us divide that square (8294) into 10 equal squares as it is I have done in the toposheet. Look at it closely. For every 2 cms, you mark one square. So you will have 10 equal squares. For 6 figure grid reference, first 3 figures

are of eastings and the second part of the 6 figure reference is of northings. We have already know easting is 82. Let us now find out the third figure from those small squares. Its in first square. So first three figures are 821 and the second part is 941. So six figure grid reference is 821941 or 822941. Did you get it? I hope so anyway.

Can you see the broken ground? (I have marked in the toposheet) What is a broken ground? They are generally found along the banks of a river. Broken ground is caused by erosion during rain when the river is in flood. It usually happens in the area devoid of vegetation.

Revision -Important Toposheet definitions

IMPORTANT DEFINITIONSDEFINITIONS FROM TOPO MAPS

REPRESENTATIVE FRACTION (RF): It is the ratio between the distances on the map to its corresponding distance on actual ground. The RF on this map is 1:50,000. 

2. SCALE : Scale is the ratio between the distance of any two points on the map and the actual distance of the same points on the ground.The scale of the given map extract is 2 cm: 1 km or 1:50,000.

3. CONTOUR: Contours are imaginary lines drawn on maps, joining all places with the same height above sea level. 

4. CONTOUR INTERVAL: The interval between two consecutive contours is called contour interval (*it is a constant 20 mts in your toposheets.) 

5. INDEX CONTOUR: Contour lines are thickened at regular intervals to make it easier to read contours. For example at every 100 mts the contour line is made darker. The darker lines are called Index Contours. 

540 6. TRIANGULATED HEIGHT: It is the height of a place which has been calculated using trigonometry, represented by a small triangle e.g. -

7. SPOT HEIGHT: The height of random places between contours shown with a dot. Eg - .425 

8. BENCH MARK - Height of a place actually marked on a stone pillar, rock or shown on a building as a permanent reference. It is written as BM 200 m. 

9. RELATIVE HEIGHT: Relative height is the height of a feature with reference to the height of the surrounding land and NOT to sea level.It is represented by the height with a small ‘r’ eg –12r. 

10. ROCK OUTCROP: It is a portion of rock jutting above the surface of the earth. 

11. SHEET ROCK: Large areas of rock where the overlying soil layers have been eroded and removed due to mechanical weathering. 

9 STONY WASTE : A large area usually in arid/semi arid regions where the finer sand/soil has blown away leaving a surface covered with boulders, stones and pebbles. 

10. BROKEN GROUND: A relief feature found mostly in dry regions around rivers and streams. It is land around river, which is totallyweathered (exfoliated) due to alternate cooling and heating. 

11. FIRELINE: A cleared pathway in a forest to prevent the spread of forest fires.

12. MIXED FOREST: A forest with more than two varieties of trees growing in close proximity to each other. 

13. OPEN JUNGLE: A forest where trees are widely scattered. 

14. DENSE JUNGLE. : A forest where trees grow very close to each other. 

15. OPEN SCRUB: Scrub is a vegetation found in regions with less than100 cms of rainfall. Therefore it indicates a dry region. 

16. BRACKISH: It is a well, which has water with very high salt content – generally unfit for drinking purposes. 

17. CAUSEWAY: It is a raised road over a small water body. (Usually a road used only in the non rainy months.} 

18. CUTTING: A portion of land, which has been cut in order to make land available for transport routes. (it is indicative of a rocky region) 

19. EMBANKMENT: They are raised rock or soil filled constructions on which roads/railway tracks are built. Also made near tanks and rivers to prevent flooding.20. FORM LINES: Form lines are contour lines, but show only approximate heights above sea level as they are used to indicate the elevations of the area which are not accessible for proper survey. Hence they are drawn as broken lines and are called 'form lines'.21. Q.C. Q.D., OC, OD,PQ, ETC : These are alphabetical codes used to represent the biggest grid sq. of 10,000 square kms.The Govt of India has adopted metric system for all measurements. All the ordnace survey maps issued by the Survey of India were drawn to the scale 2 cm = 1 km. In this system , the surveyed territory is divided into 100km X 100 km squares, and each square is denoted by English alphabets. for

example, OC, OD, PQ, PG, etc . This system of map drawing is known as National Grid Reference.22. LAYER TINTING: (colouring)While spot heights show the height of the land, they only do so at certain points. To provide an overall image which conveyed height, a technique called layer tinting was developed. Layer tinting uses different colours (or shades) to represent different heights. It is a mapping convention for darker colours to signify greater height. When using layer tinting, green is often used for low land, yellow for higher land and brown for the highest land.Layer tinting is most commonly found on physical maps. While layer tinting is useful, it does not show the detailed shape of the land.23. DEP: It is a depression often found in sandy areas where the wind, having blown away the sand, leaves a hollow or a depression.24. HACHURING: Early cartographers attempted to show surface features on maps by using the technique of hachuring. Hachures use short lines of varying thickness to show the shape and slope of the land. In accordance with this technique, the steeper the slope is, the thicker the lines are which represent it. While hachuring was initially innovative for its time, it gradually began to be replaced since the actual height of the land was not depicted.25. LIME KILN OR BRICK KILN: These are open furnaces where limestone is purified or bricks are baked for construction purpose.26. HILL SHADING: Hill shading resembles a light and shadow effect. Valleys and the sides of mountains appear as though they are cast in shadow. This is a visually striking method, which is ideal for providing an overall view of the relief of an area. Hill shading, however, does not show height which means that it is no more accurate than hachuring.

Some Common Questions Based On Toposheets

If you get these questions, look for these points in the toposheets and can write these answers:

1.Mention ay two features seen in the map extract which indicate the region has seasonal rainfall.Seasonal streams/ Broken ground/open scrub/seasonal tank/cart track motorable in dry season/narrow perennial channel in the dry bed of the river(after looking for these features, select any two features that you find on the topo sheet and write this way)

Ans: Open scrub and seasonal streams are two features in the map that indicate the region has seasonal rainfall. Rivers, steams and ponds/tanks are dry in nature.Barren land shown in white colour also indicate tht the region has seasonal rainfall.2.Mention any three features seen in the map extract which attract holiday makers.(look for various tourist destinations like temple, water falls, lakes, park, sunset points, etc and then write answers)

3. Which is the chief form of irrigation shown in the map extract? Give somE evidences to justify your answer.(look for perennial wells first, then the rivers, lakes, tanks, etc and give answer. For example, if you find the presence of many blue circles in the map, then you can write your answer this way.)Ans: The chief form of irrigation is perennial well-irrigation. Presence of blue circles scattered all over the map .

4. Give one reason to explain why the steams in grid square ......... do not join a river.(look for sandy soil , rainfall, etc)Ans; Reasons for streams not meeting the main river due to:-* presence of sandy soil which is porous* poor rainfall* high rate of evaporation. (any two ) 5. State two reasons for the absence of human habitation in some region of the map extract.( check for any features that is not suitable for human habitation – like dense forest, open shrubs, steep hills, deserts, lack of roads, etc)Ans: The region is densely forested, many streams with very steep hills. Expensive to build roads. 

6. What is the small white patch in the river?Ans: Barren island 

7. What will be the main occupation of the people be in i. highlands ii. Lowlands?i. highlands – collection of forest productsii. Lowlands - agriculture

8. Why are there no metalled roads in the mapped area?( reasons may be many- look for dense jungles, or barren land, steep hills, or many streams – and then answer according to the features,)Ans: The area has dense jungles, steep hills and no important settlement- steams and barren land discourage the building of metalled roads.

9. Give evidence to prove poor rainfall in the region.(look for features like sand dunes disappearing steams, scrub vegetation, broken grounds, etc. If you find these features, then you write the answer this way)Ans. The region has poor rainfall due to the•Presence of sand dunes•Presence of undefined and disappearing streams•Presence of scrub vegetation•Presence of broken grounds 10. Give two reasons for the presence of only footpaths in the green wash.The reasons for the presence of foot-paths are:* seep and rugged terrain makes construction of roads difficult.* temples are the only destinations in the forested mountain region and hence foot-paths are created by the pilgrims.* footpaths may be created by people who depend on forest produce. 

11. Why do so many contour lines so close together in the extract indicate about the topography?(look for steep hills, or a temple in the jungle and if u find these.................)Ans: Very steep (indicated by close contours) and hilly (indicated by many contours) land. 

12. How can we draw a climatic inference from a toposheet?

(there may be a question - what type of climate do you find in the particular area - look for these features and then write the answers accordingly -First of all, we should try to know which area of the toposheet belongs to. This gives us a faint idea about the part of the country and the type of climate prevailing there. Further, scanty amount of rainfall can be judged by seeing dry rivers, dry tanks, sand dunes and scrubs and scanty vegetation. Similarly dense forests indicate tropical monsoon climate.)

(If you find dry rivers, or dry tanks or sannd dunes, scrubs, scanty vegetation, then your answer wil be)

The area experiences scanty rainfall or poor rainfall with dry weather.

(if you find dense forests, then your answer will be)

The area experinces Tropical Monsoon climate.

Questions on occupation

13. What is the occupation of the people of a particular region from an extract of the survey map or toposheet?

(When you get a question on the occupation of the people , look for these features. Directly from a toposheet, we cannot know about the occupation of the residents. We can amplify the occupation by inferences provided on the toposheet. Therefore one must know the colours and what it indicates. For example, all of you know that yellow colour indicates agricultural land and hence agriculutre can be major occupation. Green colour shows forested or wooded area and this indicates that people follow in lumbering, furniture making, carpentry and bamboo work, etc. Presence of big towns, industrial area, railway

station, etc., indicates that people must be employed in urban services. Rest houses in hilly areas show devp of tourism. symbols of mines, may suggest that some people are employed in mining activities. if you find grassy area, then it indicates sheep or cattle rearing. Settlement along roadside indicates devp of trade and commerce. If you locate wells, tanks, canals, etc., show the cultivation of cash or cereal crops. parks, lawns, historical monuments indicate occupations like tourism, recreation, cultural devp, etc. So, my dear students, when you get a question on the occupation of the people, look for these features and write the answer accordingly. for example if you find grassy area or open shrubs, then the occupation will be sheep and cattle rearing. I hope you got me. )

14. What occupations do the people follow in Highland areas?Ans: High land regions with steep slopes have the following features: 

most of the slopes are unsuitable for agriculture. Pastures on the slopes may be fit for grazing. forestry may be a predominant economic activity in this region. flat area over plateaus may be used for cultivation.

15. How can you judge the suitablity of land for agriculture from toposheets? give a good reason.

a meandering river on the toposheet will indicate a lower or nil gradient. Thus, such a plain area would be suitable for cultivation. Dendritic or tree-like drainage pattern would confirm soft surface suitable for agriculure wheras trellised drainage pattern suggests chalk country, which is not much suited for cultivation. Sand features, e.g. barkhans and disappearing streams would indicate the dry conditions with the high temperature. These conditions are unsuitable for agriculture.

presence of broken ground would confirm seasonal flooding. Silt deposition by rivers is a good sign for agriculture. network of canals, dams, tanks and tubewells will indicate intensive use of land for agriculture. so look for these features on the toposheet and write accordingly.

For example, which are the main occupations of the people in this area? give reasons in support of your answer.

( if you see yellow wash, perennial wells, green colour,kilns on the toposheet, your answer will be like this.)

Ans: Farming and forestry seem to be the two occupations in this area because a large part of the map has yellow wash which symbolizes cultivated area. A large number of perennial wells present in the area also support this inference. Some part of the map shows presence of open jungles.......(mention, south, or north, west or east) which is indicated by green colur which suggests forestry as an important occupation there. presence of kilns shows that lime and brick making is also an occpation of some people.

POINTS TO REMEMEBR REGARDING OCCUPATIONS:

If you find KILN , then the occupation will be drying and baking bricks, pottery, limestone, etc. So you write the answer this way: The occupation is drying and baking bricks, pottery, etc due to the presence of Kiln in the area. if you find STONE QUARRY, then the occupation is quarring. If you find irrigation from wells, canals or tanks, farming is the occupation. if you find yellow wash, agriculture is the occupation of the area. if you dont find any source of irrigation, it means farming is likely to be dependent on rainfall only. mining is the occupation if you find settlements near mines or quarries.

if you find settlements along the banks of the river, then fishing is an occupation of that area. if settlement is near the forest(green colour), then the people are dependent on forest products like fruits, nuts, or leaves. there may be primitive agriculture. so when you write the answer, write this way: people are dependent on forest produce or foresty and may practice primitive agriculure. if you find large settlements, esp near the metalled roads, the occupation can also be industries, trade, services. in case they are headquarters of districts, taluqs, employment can also be in administrative sector because of the presence of large number of offices and organisations.

so please go through the toposheet properly since one question will be definite on occupation.

16. What is the brown line in grid square ............. called? What does the figure written aong this line indicate?(if it is a brown line , then it is a contour. Second part of the question - imagine you see figure 280 m ... then it means 280 m above sea level.)Ans: The brown line that we find in grid square is Contour line. The line 280 m joins places 280 m above sea-level on the map.

17. What are the brown lines seen in such abundance? What do they indicate?(same answer as question 16)ans: They are contour lines. They indicate lines joining places having the same height above sea-level. Closeness of the contours indicates mountainous topography.

17. What is a causeway? Why are there so many causeways in the map?Ans: Causeways are land raised across streams for use as metalled road or paths. The numerous streams crossing the metalled road are likely to flood them. 

18. Explain the term Depression in the map.

Ans: Depression is a shallow lowland in a sandy region often created by deflation of wind.

19. Name the geographical feature represented by white patches in the middle of the river.

Ans: The geographical feature in the middle of the river represented by white patches is an island or rocks or stores.

20. What do the following represent in the map? i. Black broken lines ii. Black curved lines.

i. Black broken lines indicate disappearing stream and black curved lines indicate broken ground.

21. Name 4 methods by which relief is shown on the map.* Contour lines * Layer Colouring/tinting * Spot height * Hill shading.

22. What is layer-tinting/colouring?It is a method, where a colour scheme is used to show relief on the map.

23. What is cartography?

Cartography is an art and science of drawing maps, diagrams and charts.

POINTS TO REMEMBER:

RELATIVE HEIGHT OR APPROXIMATE HEIGHT: REMEMBER:-This height is not taken from the sea level but with respect to the surrounding area. It may be height of a dam, bridge, sand dune, or it can be depth of a well, tank, hill, or river canal, for example 2r, 3r, 5r, 6r, etc.

Example:

●3r the relative depth of the perennial lined well is 3 metres.(if 3r is written near the symbol of perennial well. don't write height but the depth)

5r the relative height of dry tank is 5 metres ( if 5r is written near the dry tank symbol)

16r therelative height of sand dune is 16 metres. (if 16r is written near the symbol of sand

dunes)

8r the relative height of river bank is 8 metres (if 8r is written near the river bank)

PLEASE NOTE: you must write the word RELATIVE HEIGHT/DEPTH of .................................

COLOURS:

7 COLOURS are used on toposheets:

i. BLACK: Names, lines of latitudes and longitudes, broken grounds, river banks, dry rivers, surveyed trees, heights and their numbering, railway mines, telephone, telepgraph lines

ii. RED: Grid lines (eastings and northings) , their numbering, roads, cart tracks, settlements, huts and other buildings.

iii. GREEN: Forested and wooded areas, scrubs, scattered trees, orchards

iv. BLUE: Water bodies containing water like wells, rivers, etc

v. YELLOW: cultivated areas

vi. BROWN: Contour lines, their numbering, form lines, all sand features like sand dunes, sand hills, stony waste

vii. WHITE PATCHES: uncultivated and barren lands

DIRECTIONS

Directions are important for physical as well as urban features. the physical features involve the directions of rivers, streams, and the urban cities from one another.

When a question is asked regarding the banks of the river or direction of the river, the following steps should be observed.

first of all, look at the spot heights to determine the slope of the land. As you know, spot heighs are marked this way ●265 ●289 see which spot heights are higher and where it is lower, and then you will know which way or direction it slopes. the slope of the land may be from north east to south west. and if you see a river , then it flows from north-east to south-west. to know on which side or bank of the river a place is situated (a place may be a temple, settlement, town, etc)one has to locate the source of the river. Having located the direction of the river, imagine yourself standing at the source of the river f acing the main river. to your right is right bank and to your left is left bank. SO SIMPLE, BOSS!!!

when a question is askend on directions with reference to urban cites/settlements, remember these points.

some times the questions are asked on the direction of a city or settlement with a reference to the other. First of all, pay attention to the words 'FROM' a place and 'TO' a place. Imagine yourself standing on the 'FROM' PLACE and look at the TO PLACE. Use the direction arrow and write the direction.

FEW IMPORTANT TERMS:

A. Layer Tinting: Layer tinting is a method of showing relief by color. A different color is used for each band of elevation. Each shade of color, or band, represents a definite elevation range. A legend is printed on the map margin to indicate the elevation range represented by each color. However, this method does not allow the map user to determine the exact elevation of a specific point—only the range.

b. Form Lines. Form lines are not measured from any datum plane. Form lines have no standard elevation and give only a general idea of relief. Form lines are represented on a map as dashed lines and are never labeled with representative elevations.

c. Shaded Relief. Relief shading indicates relief by a shadow effect achieved by tone and color that results in the darkening of one side of terrain features, such as hills and ridges. The darker the shading, the steeper the slope. Shaded relief is sometimes used in conjunction with contour lines to emphasize these features.

d. Hachures. Hachures are short, broken lines used to show relief. Hachures are sometimes used with contour lines. They do not represent exact elevations, but are mainly used to show large, rocky outcrop areas. Hachures are used extensively on small-scale maps to show mountain ranges, plateaus, and mountain peaks.

e. Contour Lines. Contour lines are the most common method of showing relief and elevation on a standard topographic map. A contour line represents an imaginary line on the ground, above or below sea level. All points on the contour line are at the same elevation. The elevation represented by contour lines is the vertical distance above or below sea level.

(1) Index. Starting at zero elevation or mean sea level, every fifth contour line is a heavier line. These are known as index contour lines. Normally, each index contour line is numbered at some point. This number is the elevation of that line.(2) Intermediate. The contour lines falling between the index contour lines are called intermediate contour lines. These lines are finer and do not have their elevations given. There are normally four intermediate contour lines between index contour lines.(3) Supplementary. These contour lines resemble dashes. They show changes in elevation of at least one-half the contour interval. These lines are normally found where there is very little change in elevation, such as on fairly level terrain.