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The sketch represents a river valley that, lies between twt» 
[ills. In the foreground is the sea, with a bay that is partly 
iclosed by a hooked sand bar. On each side of the valley is 
terrace into which small streams have cut narrow gullies, 
fhe hill on the right has a rounded summit and gently slop¬ 
ing spurs separated by ravines. The spurs are truncated 
their lower ends by a sea cliff. The hill at the left Lerminati 
abruptly at the valley in a steep scarp, from which it slop 
gradually away and forms an inclined table-land that is tra,' 
eised by a few shallow gullies. On the map each of tb< 
features is represented, directly beneath its* position in tl 
sketch, by contour lines. 
•The contour interval, or the vertical distance in feet betwee| 
one contour and the next, is stated at the bottom of each ma; 
This interval differs according to the topography of the ai 
mapped: in a flat country it may be as small as 1 foot; in 
mountainous region it may be as great as 250 feet. < -eitai 
contour Lines, every fourth or fifth one, are made heavier tha 
the others and are accompanied by figures showing altitiul 
The heights of many points—such as road corners, summit, 
surfaces of lakes, and bench marks—are also given ou the ma 
in figures, w hieh show altitudes to the nearest foot only. Mof 
exact altitudes—those of bench marks—as well as the geodet 
coordinates of triangulation stations, are published in bullet ii 
issued by the Geological Survey. 
lettering and the works of man are shown in black. Bourn 
h as those of a State, county, city, land grant, towij 
ship, or reservation, are shown by continuous or broken linj 
of different kinds and weights. . Good motor or public roai 
arc shown by fine double lines, poor motor or private roads l:| 
dashed double lilies, trails by dashed single lines. 
Each quadrangle is designated by the name of a city, tow: 
or prominent natural feature within it, and on the margins < 
... ted the nan d joining quadmng 
widen maps have been published. Over 5,oOO quadrangles 
the United States have been surveyed, and maps of thei 
similar to the one ou the other side of this sheet have bee 
published. • 
The topographic map is the base on which, the geology ai 
mineral resources of a quadrangle are represented, and til 
maps showing these features are bound together with a descri 
tive text to form a folio of the Geologic Atlas of the Uni 
Suites. More than 220 folios have been published. 
Index maps of each State and of Alaska and Hawaii showi 
the areas covered by topographic maps and geologic folios pul 
lished by the United States Geological Survey may be obtain 
free. Copies of the standard topographic map- may be obtain 
for 10 cents each ; some special maps are sold, at different price 
A discount, of 40 per cent is allowed on an order for ma 
amounting to $5 or more at the retail price. The geolog 
folios are sold for 25 cents or more each, the price depen din 
on the size of the folio. A circular describing the folios wi 
■ 
Applications for maps or folios should be accompanied bl 
cash, draft, or monev order (not postage stamps) and should 1 1 
addressed to I 
the director, 
Untied, States Geological Survey, 
Washington, D. d 
September, 1928. 
