chapter_1 map reading

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Chapter 1

Map

Reading


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What is a topographic map ?

Large-scale map representing selected aspects of the

earths surface

Shows both physical and human features

Components of a topographic map

Title

Grid lines

Names of places

Scale Direction

Contours

Legend and symbols

Chapter 1: Map Reading


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Some basic components of a topographic map

Title

Place

name

Grid lines

Scale

Contour Symbols


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Grid lines

astings ! "ertical lines that run from south to north

Northings ! hori#ontal lines that run from west to east

Grid lines are numbered to pro"ide the coordinates of

specific features on a map

Grid reference

Set of digits formed using the grid "alues of eastings

and northings

Defines a location on a map The more digits in a grid reference$ the more precise

the location$ e%g% a si&-figure grid reference gi"es a

more accurate location than a four-figure grid reference



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our!figure grid reference

'dentifies a specific grid s(uare

)irst two digits * +alue of the easting on the left of the

s(uare

Second two digits * +alue of the northing at the bottom

of the s(uare

"#

"1

"$%& %% %'

(

)*ample:

The four-figure grid

reference for ,oint is

%&"$%



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Si*!figure grid reference

'dentifies a specific point in a grid s(uare

.ow/

1. Determine the four-figure grid

reference

2. Divide the space between the two

eastings of the grid square into ten

equal intervals

3. Count how many tenths the point is

from the left to right add this

number after the first two digits of the

four-figure grid reference

. !epeat "tep 2 for the northings of thegrid square

#. Count how many tenths the point is

from the bottom up add this number

to the end of the grid reference

)*ample:

The si&-figure grid

reference for ,oint

is %&&"$&

(

"#

"1

"$%& %% %'



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Scale

Shows what a certain distance on the map represents

on the land in the real world

Three ways to indicate scale on a map/

1. $ine scale

! %g%

2. %ord statement

! %g% 01cm on the map e(uals 234m on the ground5

3. !epresentative fraction

! %g% 61/73$333 means that one unit on the map represents

73$333 units on the ground in the real world

+$ # ,m



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1. &lace a strip of paper on theline between the two points

2. 'ar( the two points on theedge of the paper strip

3. &lace the mar(ed edge of thepaper strip on the line scale

. !ead the distance between

the two points

Reading the straight!line distance bet-een t-o points



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1. &lace one end of a string at one end of the path to be measured

)point *C+,

2. sing the string trace the curved path

3. 'ar( the end of the path on the string )point *D+,

. &lace the string on the line scale

#. !ead the distance off the scale

Reading the length of a cur.ed path



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/irection

Two ways to describe the direction of a place

1. Using compass points

! Cardinal points of the compass/ north$ south$ east$ west

! 'ntercardinal points/ northeast$ southeast$ southwest$

northwest

2. Using bearings

! Direction of a place is

e&pressed as an angle 8in

degrees9 cloc4wise from

the base direction 839

! :ase direction could be

grid north$ magnetic north

or true north



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Grid north

Direction of the "ertical grid lines 8called eastings9 on a

map

Magnetic north

Direction of the magnetic

north pole

True north

Direction of the geographicnorth pole



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0and ele.ation

1. Contours

! Lines on the map ;oining places with the same height! The number on a contour line indicates the height that the line

represents

2. Spot heights! ,oints on the map showing

the heights of hills

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2% :enchmar4s

! =ar4ed points of 4nown ele"ation which ser"e as reference

points from which the height of other places may beestablished

>% Trigonometrical stations

! ,oints mar4ed by metal discs mounted on stable foundations

such as concrete pillars

! ?sually located on top of mountains or hills

! =ay be used as benchmar4s for measuring ele"ation

+3"2

+2$



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Recognising relief features

The shape of contour lines and the spacing between

them show us the shape$ height and slope of relieffeatures


4 plateau 4 mountain 5ndulating relief


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4 gentle slope 4 stepped slope 4 steep slope


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Ri.er features

Topographic maps can gi"e us some information on the

ri"er features of an area1. River source

! ,oint where a ri"er originates

2. River mouth

! ,oint where a ri"er ends3. River course

! ,ath followed by a ri"er

! ,erennial course flows throughout the year

! 'ndefinite or seasonal course flows only during certain

seasons

4. Watershed

! :oundary between two drainage basins



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5. Drainage pattern

! ,attern formed by the ri"ers in a particular drainage basin


Trellis pattern/endritic pattern

Centripetal pattern Radial pattern


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Cross!sections

Drawing cross-sections will help you identify relief

features

.ow/

1% Draw a line 8@9 across the map where the cross-section is to

be drawn%



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>% ,lace the mar4ed edge of the paper

strip 8from Step


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Gradient

Tells us how steep a slope is

To calculate gradient/

/ertical distance/ertical distance0radient 0radient

oriontal distanceoriontal distance

gradient of 1/

chapter_1 map reading

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