Topographic Maps
Reading Preview
Key Concepts
• How do ~ers ~ewnt
elriatiot!. relief..oo $lopel
• How do you rNd" lopog,~
.....'
• What are 1<>ITle uset of
to909'aphi< INOps?
KeyT~$
• lopogtlp/'lic: m.p
• contour liM
• «>n1our inten<,,1
• ifIdoo~ contour
ra
DIScover Activity
Can a Map Show Relief?
1. Carefully cut the comen off
8 piKfl of "Irdboard so that they
look round«!. Each piece v-"Id
be at 1t!iJS1 1 centimeter vnallel'
lMn the one before.
2. Trim the long sides of the two I.,~t
pit<~ so that the long sides apPNd' wavy.
DotI't art more than 0.5 u~ntimeter Into the
ardbo.rd.
J. Tr«e the
fE) Target Reading Skill
Using I'rior I(roowl.ag. IW...,
you ,eM!, _it., what you know
.bout lopog,~ _
in"
graphic: organizl!l' lib the one
below. Iu you .ead. -ne what
you Ie..-n.
~.gest U1rdboird
pi«e on" s.hftt of
pa~.
4. TriKe the next ~rgen piece inside the tTiKing of the fim.
Don't let any lines cross.
S. TroKe the other alrdboard p1ecfl, from la'grlt 10 ~llest.
imide the other. on the ~me paper.
6. Stade. thecardboard piKes ~ 1M pap« in the Silme order
they were triKed. Compare the nac:k of aordboard piKe'S with
your drawing. How are they alike? How are they diHe<l!nt?
OM
Think It 0Vfl"
Malting Mad." If the U1.dbof,rd piKes are" model of a
~ndform. wn.t 60 the linM on the ~per repr~t1
.......... You Know
1. Some mapo.now_.
"'o."'~ lind pIooin>
,
,.,
.e.
An orienteering mttt is 001 an ordinary ra= Participants
compele 10 5ee how quickly lhcy can find a series o( Iocalions
call«l control points. The control points are Kauered over a
large pan. or Siale (oral. Orienl~rs choose a set number o(
control points. and then visil the points in any orda. In this
sport, your ability 10 read a map and USoe a compass is often
more importanl Ihan how fast you can run. In a major mm,
there may be several hundred orienteers on dozens o( learns.
AI the .start o( an orlmtming meel. you
woukI need 10 consult your map. But the: maps
IUtd in orienteering are differmt from road maps
or maps in an at1as---they're 10pogn.phic: maps.
-flGl..otl14
0rientHring helps people develop
the wll of wng • map And (om~.
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...Mapping Earth's Topography
A topocn.phic: map (bhp uh GaM it) is a map Ihowing the
surfaer fnturU or an area. Topographic ma.p5 UK' 5)'fllbols to
portr.ay the land as if )VU wn'e looking down on it &om ~
Topographic maps pn;wJdt hipty accunlt Lnronnation on the
rkntion, mid", and siopt ol the ground IUrfao:,
Mapmahn UK' contour lines to rrpruml dnatioo,
rditf, and aIopt on topognphk IBIIpI. On a lopographic
map. a contour line connects points
equal dtvatioD. In
the UniCtd Stales, most lopogr.aphic maps F conlour inltt­
~15 in ftel "'Ihtr than mt1tB.
The ~ in dtYation from contour lint 10 cootour lint is
called the contOUT int~ The contour inltl'Val lOr • gi'oal
map is aIw.I)'5 the Amt- FoI" ~pko, the map in Figurt 15 has
• contour inlttval of 200 feet. If)'OU IW1 al ont contour lint
and COWIt up 10 contour lines, )'OU Iv~ reached an tkvation
2.000 ~ aboYe where )'OU Rarttd Usually, tvtry' fifth contour
lint, known as an index contour, is darker and htavitr than the
olhen., Indo tonloun are Iabdcd with the dtvation in round
units, such as 1,600 or 2.000 fcd..hoYt sta ItYd.
or
The"""*-line on a """""". . . .
,"*" _
map
(
1
tiol• .-.d telIief.
("lib_til........r
1Opogo"""
.irIfonMri:wI doe: rtw
m.lp,.o"'*'
_ _1 rhiot tIw photogr."n
Go
nline
active<!!-,\
Fw: Iapugo $"
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Wl!ll CoOe:
'..,
. . .. - ,
"101.
::;;~,,) 'o1Iba1 do -'I the poitItI lonnedH by a _our Iinot
;:;
haw! In c:onw'IOfl1
Qapt... 1
Ci.:n
Reading a Topographic Map
Looking at a lopographic map with many squiggly contour
lines, you may fed as if you arc gazing into a bowl ofspagheui.
BUI with practice, you can learn 10 read a topographic map like
Ihe onc in Figure 16. To read a topognphic map> you must
familiarize )'Ourself with thc map's scale and symbols and
interpret the map's contour lines.
F_16
Topographic Map
The differtnt typti of symbols
on topographic maps pr<Mde
data on elevltion, reHef, ~opt'S,
and human-m~ futur~. This
United Stat~ G~al Surwy
map $hOwS part of Ttn<>esSft.
.
Contour line: deprMSioo@
""""
-- ­--
18 • CO
sc.ale Topographic maps are usually large-scale maps. large­
scale maps show a dose-up view of part of Eanh's surfa<:e.
In the Uniled States. many topographic maps arc at a scale of
t : 24,000, or I ccntimeter equals 0.24 kilometers. At this scale,
a map can show the details of elevation and features such as
rivers and c();,lsIIiIICS. l.arge buildings, airports, and major
highways appear as outlinC5 at the <:orrtct scalc. Symbols are
uSC'd 10 show hoUSd and other small features.
t~ation poin~~tff!~~~~~~~!~~~~~~~
Mapping Elevation Data
The map shows the
data
on
.....nidi the contour line a.-. bawd. Study 1M map
~ the map key. ~ ~ the quetions.
1. llHding Milps What is the contour in'",,011
on this ""'P1
2. RNding Milp' Wh" color .rt the Iowflt
points on ttle map? What f a . of elevations
do thnt points r~r~nl?
3. R• .cling Maps What color IIrt the highest
points on the map?
4. Applying COnupb What is the elevation of
the contour line labeled A7
5. Infllrring Is the ,neil between B ilr'Id C II ridge
0' II valley? How can you tell?
6. lnterprellog ON ~ibe how elN'tion
~.~';;~~~
.
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1~~'~"':"9"':~,:Iong:~""::"=·~i1:f':~:po:;":'~o~oo:""':·":'~c~l~!~~~~~'~-~~~d
.'~_or_
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Symbols Mapmakers
U~
... 1300-1_
... 121JO--l 2W
.. _'200_
a great variety of symbols on
topographic maps. If you were drawing
II
map, what symbols
­
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ee-.._.>OD_
..
would you use to represent a forest, II campground, an
orchard, a swamp. or a school! Look at Figure 16 to 5« the
symbols that arc often used for these and other featun:>.
Interpreting Contour Lines To find the elevation of a fea·
ture, begin at the labeled index contour, which is a hnvier line
than regular contour lines. Then, count the number ofcontour
lines up or down to the feature.
Reading con!Our lines is the: first stcp toward "Kcing~ an
area's topography. look at the: topographic map in Figure: 16.
l~ closely spaced contour lines indicate steep slopes. The
widely spaced contour lines indicate: gentle slopes or relatively
nat arc:u. A COnlour line: that forms a dosed loop with no otha
contour lines inside: it indicates a hilltop. A closed loop with
dashes ins.ide: indicates a dqJrmion, or hollow in the ground.
The shape of contour lines also hdp to show ridges and val­
leys. V-shaped contour lines pointing downhill indicate a ridge
line. V-shaped contour lines pointing uphill indkalC: a valley. A
stream in the vailc:y nows toward 1M open end of lhe V.
-=
~
•.
1:' ) How
_ hiltops Mel ~ ~ted
Ufoin;(Of'ItourliMs?
~=
e
"'h.IIl" Actiuity
Interpreting Data
Study tM topograph~m;,p
in figu~ 16. wtlf're are tM
ne.pet t.Iope on tM m;,p
found? How can you tell?
What. is the difflMence in
e\@yation betwHfl the rMr
and the top of aine Knob?
I.
00Apt..-,
G • 29
Uses of Topographic Maps
Topographic maps have many uses in sdenCC' and
~ngin~ring, business, gOlnnmml,
..... "
Using TOfl'09'aphic Map5
Topographk ..... p' proYiM the ~tI
~ r y for the planning 01 highways.
bridges. and othet lar~ (0MttUCti0n
project-.
Section
Supposoe that you a~ an cnginc= planning II routt for II
highway over II mountain pass.. Your design for I~ high­
way needs to soh~ SCVff'al problem5- To design a we
highWlI)', you need II routr that avoids the stccpcst
slopes. To protect the alTa's watn supply, the highway
must Slay II certain distance from rivers and lakes. You
also wanl 10 find II routt thaI avoids houses and other
buildings.. How would you solve these problems and
find the best roUlt for lhe highwar. Yoo would probably
begin by studying topographic maps.
BusintsSeS usc lopographk map$ 10 help dKide
where to build new stores, housing, or factories. Local
governments usc them to decide where to build new
schools and other public buildings. Topographic maps
have recreatioml uses, 100. If you wert planning II bicy­
cle trip, you could usc II topographic map to see where
your trip would be flat or hilly.
4 Assessment
'@Target Reading Skill Using Prior Knowledge
~Kw )'Ourgr<ipnk orpniznand ~ it ~
on wh.11 )'Ou justlnrrn:d in 1M 5«tion.
Reviewing Key Concepts
1. a. Defining What iJ, a lopographK map?
b. EJlplaining How do u.>pographk maps
~l'Dmt ckv;ltion;,md relict?
(. C.kut.ting If the conll:)ur ;nln"v.J.l On a
lopographk map i$ SO met~ how much
difftrmcc: in tkvation do 12 COfltour lines
rtprt5t1lt?
2. a. Rtoit:wi"9 What do you IK'C'd 10 know
about. topographic map in order to rnd it?
b. CorTIpIlrlng MId Contratlng Comp;lrt the
way ~ctp "'opc.'$ art rtprCS<'n~on a topog­
raphic map with lht way gallle $Iopc.'$ art
~l'Dmltd.
(. Inferring Read;ng a map,)'Ou see V-shaped
contour lines thaI poinl uphill. Whal bod
featuR' would)'O\l find in this ilrtar
lO. G
and everyday life.
1. a. Usting WhataI"C four main uses of
topognphk maps?
b. ~ Solving Suppose: thaI )'Our
community n«ds alargc. ltat ~;te for a
IKW athlnk field. How wuld you me a
lopognophk map of )'Our ami 10 idenlify
possible sites?
Writing in Science
~
Dk1ldll a • Write a descriptiW
pIlr~raph of a simple route fmm oM point
on the INIp in f9- 16 to .. 1OtI_ point.
Your !*"agrlph w.ould provide thI stII1>ng
p<Hnt. but not the end point. InducIe cMWh
sud'l1S dlrtal'Ke, (()l'IIplSS direction. and
topogl.phy IkJng the 1'OUle. stw. you­
paoragraph with ~ 10 see jf!hey c.-.
foIb1w your dit'ectioM.