14 THE UNITED STATES GEOLOGICAL SURVEY. [bull.227. 
GENERAL RESULTS ACHIEVED BY THE SURVEY. 
Among the more important results achieved by the organization are 
the following: 
A complete topographic map (see pp. 55-71) of 929,850 square miles 
of the area of the United States, which, including Alaska, amounts to 
3,622,933 square miles. In other words, the Survey has finished the 
mapping, on more or less detailed scales, of 20 per cent of the area of 
the country, including Alaska, and 31 per cent excluding Alaska. 
This map is published in the form of 1,327 separate atlas sheets, 
printed in three colors from copperplate engravings. The topographic 
maps of the Geological Survey have greatly expedited investigations 
by cities of their water supply, and have been of the highest value to 
railway companies and State highway bureaus in designing and plan- 
ning their projects. The improvement of highways in New York, 
Maryland, Massachusetts, and other States has been greatly facilitated 
and the cost of the State work materialh 7 reduced by these maps. 
The elaborate and valuable reports recently completed on the future 
water supply of the cit}^ of New York and on the New York State 
Barge Canal have been rendered conclusive in large measure only 
through the agency of the existing topographic maps. 
Man}^ of the broader problems whose solution must necessarily pre- 
cede the final geologic mapping of the country have been solved. 
The geologic mapping of the surface formations has been extended 
over about 171,000 square miles, and 106 geologic folios have been 
published, while nearly an equal number are in various stages of 
preparation. These folios consist of descriptive text, a topographic 
sheet, geologic sheets for areal and economic geology, structure 
sections, columnar sections, etc. (see pp. 99-100). Each folio thus 
presents a practical^ complete history of the topography, geology, and 
mineral resources of the area described. 
Coincident with the geologic work, important experiments and 
investigations into the physical characteristics of rocks in various 
processes of formation, and of volcanic and geyser action, have been 
conducted in the physical laboratory (see pp. 53-55), and man} r 
important conclusions have been reached. The chemical laboratory 
(see pp. 50-53) and the petrographic laboratory (see p. 27) have been 
engaged in solving, chemically and microscopically , the more impor- 
tant problems connected with rock composition and structure, while the 
paleontologic section (see p. 27) has aided in solving stratigraphic and 
structural problems by the classification and identification of the fossil 
remains of plants and animals. 
The engraving and printing division (see pp. 113-117) has engraved 
1,421 series of copper plates for as many topographic atlas sheets, 
each series consisting of three plates, one for each color. It has litho- 
