262 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 19 38 



structures of the earth's crust, in problems of sedimentation, ancient 

 shorelines, and continental history. In this connection, David White's 

 carbon ratio theory deserves particular mention. The essence of it is 

 that organic substances in sedimentary rocks share in the ordinary 

 metamorphic changes induced by compaction and folding of the 

 deposits. Oils and coals of different ranks are produced and modified 

 by these changes at relatively low temperatures and by a sort of 

 cracking process, whereby the more volatile hydrocarbons are liberated 

 while the fixed carbon remains, thus increasing the ratio of the "fixed" 

 to the volatile carbon. As these metamorphic effects become more 

 intense, the cracking process reaches a "dead fine" beyond which no 

 oil or gas pools may be expected. This theory explains many facts 

 regarding the mode of occurrence of petroleum and some of the differ- 

 ences in its character from place to place. By indicating areas where 

 the search for oil would be unprofitable, it has saved producers 

 millions of dollars. 



The relationship of geology to the life and interests of a community 

 is nowhere more definitely recognized and more strongly appreciated 

 than among the people living in the oil-producing parts of the country. 

 Even a brief sojourn in such a community suffices to show that the 

 common man has a keen understanding of such geologic terms as 

 anticline, structure, dip, and strike, and of the part these features 

 may play in finding oil. 



GEOLOGY IN THE CONSTRUCTIONAL INDUSTRIES 



In recent years the imagination of the public has been stirred by 

 plans involving engineering construction projects on an unprecedented 

 scale. Some of these projects are already in progress and popular 

 attention has been directed to such centers as Norris, Tenn. ; Gunters- 

 ville, Ala.; Boulder Dam, Ariz.-Nev. ; Bonneville Dam, Oreg.-Wash.; 

 Grand Coulee Dam, Wash., and Fort Peck, Mont., where construc- 

 tion of large river-control projects is already well advanced. 



The geologic conditions at each of these sites presented problems 

 or even hazards that had to be solved and met by special engineering 

 devices before success for the constructional end of the project could 

 be assured. At one site, for example, the difficulties centered in the 

 relative porosity and cavernous character of the limestones on which 

 the dam was to be seated. At another, ground movement, through 

 landslides, introduced serious hazards. At still another, the occur- 

 rence of large supplies of hot water denoting disturbed structural 

 conditions at the proposed dam site had to be taken into account. 

 The engineers in charge, mindful of previous disasters where work of 

 this sort had been done without sufficient regard to attending geo- 

 logic conditions, called upon geologists for help. As the sites selected 



