THE UNITED STATES GEOLOGICAL SURVEY. 497 



and mapping of the gold, silver, and coal-bearing rocks of Colo- 

 rado, Utah, Wyoming, Idaho, and Montana, and, if feasible, to 

 begin work in Arizona and New Mexico. In this connection de- 

 tailed studies will be made of such typical mining districts as will 

 throw light upon and aid in the development of similar districts 

 elsewhere. 8. The Pacific slope: The mapping and study of the 

 gold belt of California has been greatly advanced, but a number 

 of years will be required to complete it, and this will be one of the 

 essential features of the work in this region. Areal work will 

 also be continued in southeastern Oregon ; and it is planned to 

 begin the mapping of the coal areas of Washington, and the study 

 of the coal resources of the Pacific slope. 9. The interior south- 

 west and the region of the Great Plains, from the Rio Grande to 

 the British boundary. In this broad area special attention will 

 be given to areal mapping, and also to the mineral resources in 

 coal, iron, lignite, cement clay, building stones, the occurrence of 

 artesian water, etc. 



The resources of the interior Mississippi basin are more gener- 

 ally known, and the w?rk there will be of a special character, or 

 in co-operation with State surveys. 



The investigation of the water resources of the arid and semi- 

 arid regions and of the country at large will be systematically 

 carried forward until the available water supply from every arte- 

 sian source and from every stream in the United States is accu- 

 rately known, both for irrigation and power. This project, if car- 

 ried out, will cover a number of years, and it will doubtless repay 

 the outlay in the assistance it will give to the development and 

 prosperity of all sections of the country. 



If the proposed amendment relating to the geology of highways 

 is adopted by Congress, material entering into road construction 

 will be obtained by field parties of the survey and also through 

 State surveys, road commissioners, and individuals ; and tests will 

 be made to enable all who are engaged or interested in the con- 

 struction of highways to make an intelligent selection of materials 

 to be used. It has been said that the status of a nation's civiliza- 

 tion may be estimated by its facilities of communication within 

 its own borders. Believing this to be true, the policy of the Geo- 

 logical Survey will be to assist in perfecting all roads by address- 

 ing itself to the jDurely geologic question of choice of materials 

 entering into their construction. 



The investigation of the phenomena of the great ice invasion 

 of the north will be continued until all of its important features 

 have been studied and interpreted, and the formations resulting 

 from its influence, direct and indirect, have been determined and 

 mapped. 



It is also proposed to co-operate with individuals and State 



VOL. XL VI. 36 



