22 ILLINOIS ACADEMY OF SCIENCE 



work done by Evans, Hayden and Meek in the Bad Lands of 

 the Missouri, had whetted the desires of numerous investi- 

 gators. Willing workers were abundant during the fourth 

 decade, 1870-79, and Congress not difficult to persuade into 

 granting the necessary funds. Hence expedition after expedi- 

 tion was organized and sent out, some purely military, some 

 military and geographic, with geology only incidental, and 

 others for the avowed purpose of geological research. 



Under such conditions was inaugurated the work which 

 culminated, in 1879, in the organization of the present U. S. 

 Geological Survey, which, for breadth of scope and financial 

 resources, is without counterpart in the world's history of sci- 

 ence. 



The more important of the expeditions above referred to 

 were Hayden's Geological Surveys of the Territories; King's 

 Geological Survey of the Fortieth Parallel ; Powell's Surveys 

 of the Grand Canyon of the Colorado and adjacent regions; 

 and Wheeler's Geographical Surveys West of the One-hun- 

 dredth Meridian. 



It is possible only to mention the organizations of these four 

 decades and it is necessary to omit the results of the work, 

 except to say that the knowledge of the mineral resources of the 

 States and territories was extended rapidly and made a mat- 

 ter of public record by the frontier explorations. Much of 

 the work of the early 50's was wonderfully well done. 



LATER INVESTIGATIONS 



Topographic mapping is of great value as a basis for study 

 of mineral resources. WTiile at least three states have made 

 such surveys systematically, the U.S. Geological Survey has 

 executed nearly all topographical surveys now available to the 

 public. The total surveyed to date equals 40 per cent of the 

 country. In this work about twenty states co-operate and fur- 

 nish half of the necessary funds. Practically $600,000 was 

 spent for public topographic surveys in the United States dur- 

 ing the fiscal year 1913. More than 22,500 sq. mi. (one half 

 of Illinois) was actually surveyed. The total surveyed to date 

 equals 40 per cent of the country. 



General geological surveys of specific areas have been the 

 approved type for public and corporation work, and maps, 

 (Figure 3) and reports based on states, counties, quadrangles, 

 or other units have aimed to portray the kinds and relations 

 of all the exposed formations and to present the facts relating 



