PROJECT
www.jaconline.com.au
Draw a cross-section
A cross-section shows the shape of a feature (such as a mountain) viewed from the side, as if cut through with a knife.
Cross-sections are constructed using the contour lines on a topographic map. (You may like to refresh your memory
about topographic maps by reading the information box on page 2 of this worksheet.)
In this worksheet, you will draw two cross-sections from the topographical map of Mt Etna included on page 3. (You
may find it easier to draw these if you first enlarge the map on a photocopier.) On completion, explain in a couple of
paragraphs any similarities and differences in the two cross-sections, and what this tells you about the terrain in each
case. Your cross-sections will be drawn between:
•
•
grid reference 227033 (name it A) and grid reference 252047 (name it B)
grid reference 239054 (name it C) and grid reference 241026 (name it D).
In each case you will start and finish on a contour line. This will mean making a very minor adjustment for your start
and finish points, once you have pinpointed
your grid references.
The following example is provided to remind
you how to draw a cross-section.
Map by MAPgraphics Pty Ltd, Brisbane
Drawing a cross-section
1.
Line up the edge of a piece of plain paper
along the line marked XY.
2.
Make a small vertical mark on your paper
where each contour line meets it. Also
draw small marks below X and Y and label
them X and Y. Near each vertical mark,
write the height of the contour. (Use the
contour interval to help you work this out.)
3.
Line up your marked-up piece of paper
against a graph you have drawn. Your
graph should be exactly the same width
as the length of the line between X and
Y. Line up the X with the vertical axis of
your graph. For each vertical mark on your
piece of paper make a corresponding dot
on your graph (to record the height of the
contour above sea level).
4.
Join the dots to create your cross-section.
The first 18 have been plotted for you
here.
5.
Give your cross-section a title. If you wish,
you could shade the area under the line,
so that the shape of your completed
cross-section is clearer.
© John Wiley & Sons Australia, Ltd 2005
2004-09-x-section.pdf
(Page 1 of 2)
PROJECT
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Topographic maps
Topographic maps show the relief (height and
shape) of the land using contours. They also
show physical features such as forests, rivers
and lakes and human-made features such as
roads, railways and settlements. The key on a
topographic map uses conventional signs to
show the major features.
Contour lines
Contour lines are superimposed on topographic
maps. These are numbered lines that join places
of equal height above sea level on a map.
Contours show the height, shape and location of
hills and mountains in a landscape. The
difference in height between one contour line
and the next is always the same. This is known
as the contour interval.
On any contour map, evenly spaced contours
mean an even slope, close contours mean a
steeper slope and widely spaced contours mean
a gentle slope or flat area. Spot heights are also
given to show the actual height of particular
locations. The highest points of a region are
usually shown with spot heights.
Grids on a topographic map
A square grid is superimposed on topographic
maps. These grids are numbered with two-digit
numbers on the map’s margins. Lines that run
up and down the map (north/south) are called
eastings, because the numbers increase as you
move east. The lines running across the map
(east/west) are called northings because the
numbers increase as you move north. Easting
and northing numbers can be put together to
form a four-figure grid reference — the easting
is always given first (e.g. 2304).
Four- and six-figure grid references
This six-figure grid reference of point X is
23
6
From the eastings
04
6
From the northings
The four-figure area reference will tell you the
That is: 236046
grid square in which a feature will be found. To
pinpoint a more precise location of a feature, a
six-figure grid reference is required. To work out the six-figure grid reference of a particular point on a map, you need to imagine that
the distance between two eastings and two northings can be divided into 10 equal segments (tenths). These imaginary lines divide the
spaces between one easting and the next into 10 equal columns, and the spaces between one northing and the next into 10 equal rows
By way of example, an extract from the Mount Etna topographic map has been included above. You will note that the point to be
identified (X) lies in the grid formed by eastings 23 and 24 and northings 04 and 05. Estimate on which imaginary lines between these
two eastings and two northings this point is located. This will give you the third and sixth numbers respectively for your six-figure
grid reference (e.g. 236046).
Reference:
SOSE Alive 3, pp. 108–9 ▪SOSE Alive Geography 2, pp. 12–13
© John Wiley & Sons Australia, Ltd 2005
2004-09-x-section.pdf
(Page 2 of 2)
22
23
24
25
26
154
RANDAZZO
822
Passopisciaro
Monte Calciniera
809
Linguaglossa
973
05
Maletto
1273
1010
967
583
1316
A
2847
Monte Etna
2934
04
3323
Nunziata
0
2942
200
00
25
B
GIARRE
0
2640
2182
742
Mascali
Monte Scorsone
1603
300
Monte Minardo
1304
1734
00
1482
1284
Monte Piniteddu
1398
Santa Venerina
03
1000
852
1039
BIANCAVILLA
Stazzo
San Tecla
262
Santa Maria
779
Nicolosi
Pedara
Trecastagni
ACIREALE
Aci Sene
Antonio
Aci Platani
500
BELPASSO
02
200
445
PATERNO
San Pietro
Clarenza
22
Palermo
Messina
Mt Etna 3323 m
Sicily
23
Contour interval 100 metres
Gravina di
Catania
500
1398
15 kilometres
02
Aci Trezza
MEDITERRANEAN
Aci Castello SEA
CATANIA
CATANIA
Scale 1:250 000
10
San
Giovanni 380
24
Siracusa
5
Mascalucia
MISTERBIANCO
325
0
RIPOSTO
ADRANO
382
04
Zafferana
Etnea
15
03
05
Monte Crisimo
1345
Monte Pizzillo
2414
1773
BRONTE
1632
1632
25
Small built-up area or buildings
Index contour line with height in metres
Contour line
Spot height in metres
Medium or dense forest
Lava flow
Map by MAPgraphics Pty Ltd, Brisbane
N
26
Highway or Freeway
Major road
Minor road
Tracks
Railway
Built-up area