United States Geological Survey is making a standaib 
[graphic atlas of the United States. This work has been fn 
ess since 1882, and its results consist of published mapajo! 
than 42 per cent of the country, exclusive of outlying 
topographic atlas is published in the form of maps -oc 
s measuring about 16£ by 20 inches. Under the gen are 
adopted the country is divided into quadrangles boun<fst 
jarallela of latitude and meridians of longitude. Tkfew 
Irangles are mapped on different scales, the scale seleqet 
ach map being that which is best adapted to general use it 
levelopment of the country, and consequently, though tin 
kard map of nearly uniform size, they r ea 
[fferen es. On the 1< tet 
hie scales showing distances in feet, meters, and miles. *1 
tion, the scale of the map is shown by a fraction expreasifa 
:ed ratio between linear measurements on the map and dor 
pnding distances on the ground. For example, the -Oil 
means that 1 unit on the map (such as 1 inch, 1 foot, <B? 
Lr) represents 62,500 similar units on the earth’s surfaced 
Ithough some areas are surveyed and some maps are com 
[land published on special; scales - for special purposes, H 
Idard topographic surveys for the United States proper H 
resulting m; have for many years u divided into thB 
s; differentiated as follows i 
Surveys of areas in which there are problems of gr 
lie importance—relating, for example, to mineral devel< 
t, irrigation, or reclamation of swamp areas—are made wi 
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separated, by ravines. The spurs are truncal 
lCfir lower ends by a sea cliff. Tlie bill at the left term 
>ru|>tly at the valley in a steep scarp, from which it 
raduall away and forms an inclined table-land that is 
b r a few shallow gullies. On the map each of 
Janice* is represented, directly beneath ite position j 
vetxjb. by contour lines. MOE] p , 
* contour interval, or the vertical distance in feet be 
ie contour and the next, is stated at the bottom c each 
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bis interval differs according to the topography of the 
tapped:-in aflat country it maybe as small as 1 foot: 
tountaiuous region it may be as great as 250 feet. O 
on tom lines, every fourth or fifth one, are made heavier 
ie others and are accompanied by figures showing alt 
'he heights of many points—such as road comers, sun 
lufe. of lakes, and bench marks—are also riven cm tip 
) Jfcuree. which show altitudes to the nearest toot only, 
fair thudes—--those of bench marks—-as well, as the g I 
,i ,r ulation s' e publish 
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csifed by the Geological Survey. Vj ■ , . 
Lettei ing and the works of man are shown in odaefc P> 
rum such as those of a State, county, city, land grant, 
hip or reservation, are shown by contiguous or broken 
f' different kinds and weights. Good motor or put lie 
e shown by fine double lines, poor motor or private roa« 
led double lines, trails by dashed single lines, 
lach quadrangle is designated by the name oi a city, 
^prominent natural feature within it, and on the marc 
* A It » 9 1 
