Iti diiidweBmG' dfotvwudt 
* ® rGcencrtuA 
r 
Dam Dam witli lock 
t anal lock i .S, towns!. 
poertt (UivXret-im ) S^CtiOOl 1 
ancl locatdfl 
BM X ^ 
1 cr*r : ff. 
l?32 
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ntfur** H'ithoisi- l*Ua?-iruj ) 
■ — ■ - i — * - ~ —— - 
ftiTJttuiff* n.rhpdon 
r **ry^Mr vjusftf / 
RELIEF 
(printed in brown ) 
F ; da ires 
{*hx»ving hjfijght aboie 
ni-euti a«'X Zevw£ lastn 1 
m *nlo ILy Ajrrwmtirut 8 
Goartorarc 
(Contour* ihmdng 
d#**d \i ay "H 
priatoti' in- b2ue / 
i ■ •• I : ' ^ssioj 
oontaBr-s 
VTasii 
Glim 
/‘o/' aTvmm* cxrwfnitT'*) 
Mixu? dumps 
rrenaa 
Bridges Dr^ovbiidges Feirv 
( porn* urjfr&'&Xfn J 
Foard 
*, 09 ? Small park op T;.aangulciDoii i . S.mineral Bcnxndax^l 
I 
traverse rnt >ntrmeiTt 
-*>-LH 
P xmel Mine tonnel I.i^Ltthoose 
f 8 halting direxstianj firbearoil 
MiVATER 
'printed in blue) 
- L$S 
Lightsliip *. Idfr* s.-cveq| 
- 
Aqueducts or 
waierpipes 
Aqoeduct 
tunnels 
I ,alte or 
porn! 
I 
I 
J 
1 btMS&S 1 
Salt xnarsh fresh marsh Grassv pond Tidal flats 
e United States (geological Survey is making a stain 
graphic atlas of the United States. This work has bfljj 
ess since 1882, and its results consist of published ina] 
than 40 per cent of the country, exclusive of ou$3. 
asions. ’■ 
is topographic atlas is published in the form or maj 
sheets measuring about 16i by 20 inches. Under tue 
•al plan adopted the country is divided into quadrangles 
ded by parallels of latitude and meridians ot longitude, 
e quadrangles are mapped on different scales, the scale 
ted for any quadrangle depending on its nature and its 
iture d ev elopto cn t. and consequently though the 
x^vprrsstnxtjs au rmagmnn j miu -v** i - r 
part of which is at the same altitude above sea level. Such a 
line could be drawn at any altitude, but in mappiug only the 
contours at certain regular intervals ot altitude are shown. 
The line of the seaeoast, itself is a contour, the datum or zero 
of altitude being mean sea level. The 20-toot contour, foi 
gradually away and forms an inclined table-land that 
versed by a few shallow gullies. On the map each ot 
iatures is represented, directly beneath its position i 
:etch, by contour lines. - 
The contour interval, or the vertical distance in feet bel 
ie contour and the Dext, is stated at the bottom ot eachj 
'his interval differs according to the topography of th< 
mapped; in a hat country it may be as small as 1 foot! 
mountainous region it may be as great as *2.‘>0 feet. U 
contour lines, every fourth or fifth one. are made heavier! 
the others and are accompanied by figures showing ain 
The heights of many points—such as road corners, sun 
surfaces of lakes, and bench marks—are also given on th[ 
/ 
