WHAT THE U. S. GEOLOCICAL SURVEY HAS 

 DONE IN TWENTY-FIVE YEARS 



IN commemoration of the twenty- 

 fifth anniversary of the formation 

 of the U. S. Geological Survey, 

 the Survey has published a small vol- 

 ume giving an account of the origin, 

 development, and present organization 

 of the Survey, with short summaries 

 of its various operations during the 

 first quarter century of its existence. 

 Among the more important results 

 achieved by the organization are the 

 following : 



A complete topographic map 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 26 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 copper-plate engrav- 

 ings. The topographic maps of the 

 Geological Survey have greatly expe- 

 dited investigations by cities of their 

 water supply, and have been of the 

 highest value to railway companies and 

 state highway bureaus in designing and 

 planning their projects. The improve- 

 ment of highways in New York, Mary- 

 land, Massachusetts, and other states 

 has been greatly facilitated and the cost 

 of the state work materially reduced by 

 these maps. The elaborate and valua- 

 ble reports recently completed on the 

 future water supply of the city 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. 



Many of the broader problems whose 

 solution must necessarily precede the 

 final geologic mapping of the country 

 have been solved. The geologic map- 

 ping of the surface formations has been 

 extended over about 171,000 square 

 miles, and 106 geologic folios have been 



published, while nearly an equal num- 

 ber 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. Each 

 foiio thus presents a practically com- 

 plete history of the topography, geol- 

 ogy, and mineral resources of the area 

 described. 



Coincident with the geologic work, 

 important experiments and investiga- 

 tions into the physical characteristics of 

 rocks in various processes of formation, 

 and of volcanic and geyser action, have 

 been conducted in the physical labora- 

 tory, and many important conclusions 

 have been reached. The chemical labo- 

 ratory and the petrographic laboratory 

 have been engaged in solving, chem- 

 ically and microscopically, the more 

 important problems connected with rock 

 composition and structure, while the 

 paleoutologic section has aided in solv- 

 ing stratigraphic and structural prob- 

 lems by the classification and identifi- 

 cation of the fossil remains of plants and 

 animals. 



The engraving and printing division 

 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- 

 graphed on stone the colors, ranging in 

 number from 10 to nearl} 7 30, necessary 

 for distinguishing in each of about 100 

 geologic folios the various formations 

 and outcrops. It has printed several 

 editions of most of the topographic 

 maps and at least one edition of the 

 geologic folios, besides revising both as 

 occasion therefor has arisen, and en- 

 graving and printing miscellaneous state 

 and United States maps. 



The hydrographic branch, including 

 the reclamation service, has recorded 

 during the last 15 years the maximum, 

 minimum, and mean discharges of all 

 the more important rivers, and for 



