THE GEOLOGICAL HISTORY OF NEW YORK STATE 11g 
accompanied by figures stating elevation above sea level. The 
heights of many definite points, such as road corners, railroad sta- 
tions, railroad crossings, summits, water surfaces, triangulation 
stations, and bench marks, are also given. The figures in each 
case are placed close to the point to which they apply, and express 
the elevation to the nearest foot only. ... All water features are 
shown in blue, the smaller streams and canals in full blue lines, 
and the larger streams, lakes, and the sea by blue water lining. . . . 
The works of man are shown in black, in which coloring all letter- 
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Fic. 40 Ideal sketch and corresponding contour map (U. S. 
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ing also is printed. . . . Houses are shown by small black squares 
which in the densely built portions of cities and towns merge into 
blocks. Roads are shown by fine double lines, trails by single 
dotted lines, and railroads by full black lines with cross lines. 
Other cultural features are represented by conventions which are 
easily understood. The sheets composing the topographic atlas are 
designated by the name of a principal town or of some prominent 
natural feature within the quadrangle and the names of the adjoin- 
ing published sheets are printed on the margins. They are sold 
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9 
