The United States Geological Survey is making a standard 
pographie atlas of the United States. This work has been.jn 
ogress since 1882 , and its l vs ulus consist, of published maps 0 f 
, than 40 per cent of the country, exclusive of outlying 
ore 
i 
This topographic atlas is published in the form of maps on 
gets measuring about 16J by 20 inches. Under the general 
n adopted the country is divided into quadrangles bounded 
parallels of latitude and meridians of longitude. These 
imlrangles are mapped on different scales, the scale selected 
, each map being that which is best adapted to general use in 
■ e development of the country, mid consequently, though the 
Imdard maps are of nearly uniform size, they represent m 
‘ different sizes. < )n the lower margin of each map are printed 
ophic scales showing distances in feet, meters, and mile?. In 
Idition, the scale of the map is shown by a fraction expressing 
fixed ratio between linear measurements on the. map and cor- 
jponding distances on the ground. For cxumpW-the scale 
means that 1 unit on the map (such as 1 inch, 1 foot, or 1 
l e ter) represents §2,500 Similar units on the eafffll's surface. 
Although some areas are surveyed and some maps are colli¬ 
ded and published on special scales for special purposes, the 
mdarj topographic surveys for the United States proper and 
le resulting maps have for many years been divided into three 
[pee, differentiated as follows: 
1. Surveys of areas in which there are problems of great 
iblic importance—relating, for example, to mineral develop¬ 
ment, irrigation, or declamation of swamp areas—are made with 
dficieui accuracy to be mod iu the publication ~ni' map? on ; 
:ale of ^ (1 inch=: one-half mile), with a mtour interval of 
5, or 10 feet* jk 
2. Surveys of areas in which there are problems of average 
iblic importance, such as most of the basin of the Mississippi 
[id its tributaries, are mode with sufficient accuracy to be nsejd 
l the publication of maps on a scale of c> ,^ ( (1 ineh = nearly 
mile), with a contour interval of 10 to 25 feet, 
3. Surveys of areas in which the problems are of minor 
ublie importance, such as much of the mountain or desert 
?gion of Arizona or New Mexico, are made with sufficient 
ecu racy to be used in the publication of maps on a scale oi* 
~ (1 inch=nearly 2 miles), with a contour interval of 25 to 
00 feet. 
A topographic survey of Alaska has been in progress since 
808, and nearly 37 per gent of irs area has now been mapped, 
.bout 10 per cent of the Territory has been covered by recon*- 
[aissance map? on a scale of or about 10 miles to an 
ich. Most of the remaining area surveyed in Alaska lia? 
[een mapped on a scale of . but about 4,000 square mile 
ec.aw* 
[a? been mapped on a scale of 
About half of the Hawaiian Islands has been surveyed, ant 
e resulting maps are published on a scale of 
The features shown on these maps may be arranged in dire 
oups—(1) water, including seas, lakes, rivers, canals, swampp 
nd.other bodies of water; (2) relief, including mountain? 
, valleys, and other features of the land surface; (3) cultur 
works of man), such as towns, cities, roads, railroads, an< 
r _ 
boundaries. The conventional signs used to represen' 
features are shown and explained below. Variations apjj 
some earlier maps, and additional features are represent* 
some special maps. 
All the water features are represented iu blue, the sj 
streams and canals by single blue lines and the larger tftreoin^ 
tbe lakes, and the sea 1 1 
mittent streams—those' whose beds are dry for a large part of 
the vear— fire shown by Imps of blue dots and < Lushes. 
Relief is shown by contour lines in brown, which on some 
maps are supplemented by shading showing the effect of light 
thrown from the northwest across the area represented, for the 
purpose of giving the appearance of relief and thus aiding in 
the interpretation of the contour lines. A contour line repre¬ 
sents an imaginary line on the ground (a contour) every part 
of which is at the same altitude above sea level. Such a line 
could be drawn at any altitude, but in practice only the con¬ 
tra ris at certtaiu regular intervals of altitude are shown, The 
line of tlie^eacoast itself is a contour, the datum or zero of alti¬ 
tude being mean sea level. The 20-foot contour would be the 
shore line if the sea should rise 20 feet. Contour lines show 
the shape of the lulls, mountains, and valleys, as well as their 
altitude. Successive contour lines that am far apart on the 
map indicate a gentle slope; lines that are close together indi- 
«!i.te a ste ep slope; and line? that ru tog ether indicate a cliff. 
form 
\ 
■ 
L I iff. The hi 
iptiy at the valley in a steep scarp, from which it s 
•adually away and forms an inclined table-land that is 
ersed by a few shallow gullies. On the map each of 
features is represented, directly beneath its position io| 
sketch, by contour lines. 
The contour interval, or the vertical distance in feet bet! 
one contour and the next. Is stated at the bottom of each 
This interval differs according to the topography of the 
mapped: in aflat country it maybe as small as 1 foot; 
mountainous region it may be as great as 250 feet. Ce 
contour Hues, every fourth or fifth one, are made heavier 
the others and are accompanied hy figures showing alti 
The heights of many points—such as road corners, sun 
surfaces of lakes, and bench marks—are also given on the 
in figures, which show altitudes t:o the nearest foot only, 
exact altitudes—those of bench marks—as well as the get 
coordinates of triangulation stations, are published in bul 
issued by the Geological Survey. 
lettering and the works of man are shown in black. B( 
*- 
aries, such as those of a State, county, city, land grant, tj 
ship, or reservation, are shown bv continuous or broken 
of different kinds and weights. Metaled roads are show 
double lines, one of which is accentuated. Other public 
are shown by tine double lines, private and poor roat 
■SBhed double liues, trails by dashed single lines. 
Each quadrangle is designated by the name of a city, 
prominent natural feature within it, and on the marj 
map are printed the names* of adjoining quadra 
h maps have been published. Over 3,000 quadrant 
_re been surveyed, and maps of 
Lk ,* •lathe other side of this sheet have 
is the base on which the geologl 
_ quadrangle are represented, anj 
>s showing these features are hound together with a dtj 
text to form a folio of the Geologic Atlas of the II 
tes. More than 200 folios have been published, 
ndex maps of each State and of Alaska aud Hawaii ?ln| 
? areas covered by topographic maps and geologic folios 
hed by the United States Geological Survey may be obt 
i uce. Copies of the standard topographic maps may be obi 
I for 10 cents each; some special maps are sold at different 
l A discount of 40 pet cent is allowed on an order for 
\ amounting to $5 or more at the retail price. The gel 
folios are sold for 25 cents or more each, the price depel 
gn the- size of die folio. A circular describing the fohVj 
3 sent on request. 
Applications for maps or folios should be accompani 
util, draft, or money order (not postage 'tamps) and shoj 
Jdreesed to 
THE DIRECTOR, 
United States Geological Surm 
Washington, 
January, 1924. 
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