520 SHAW: SEDIMENTATION 



sary that comprehensive systematic studies of modem sed- 

 imentation be undertaken from this interpretative standpoint. 

 Such men as Lyell and De la Beche made a good beginning, but 

 the present problems of earth history were beyond their horizon, 

 and the older studies of sedimentation were, furthermore, gen- 

 eral in character and descriptive of the thing in itself rather than 

 of its significance. The idea of the necessity for criteria for the 

 discrimination of various climatic and physiographic controls in 

 the making of ancient sediments was until recently a point of 

 view not conceived." 



Blackwelder says that because of his interest in the earth's 

 physical history and his experience with sedimentary rocks he 

 has been "especially impressed with the advantages to be gained 

 from painstaking study of the consolidated formations" and in 

 particular their lateral variations. He suggests "the exhaustive 

 study of individual types or type groups of sediments in both 

 modern and lithified state." 



Kindle is especially interested in lake and sea bottom deposits, 

 in ripple marks, in migration of shores and transportation of 

 Uttoral deposits, etc. Steiger and Wells present an outline of 

 needed and practicable chemical and physico-chemical work. 

 Others have contributed valuable suggestions. 



SUMMARY 



Although to progress in the understanding of sediments is 

 somewhat difficult the need is real. Much can be accomplished 

 through coordination, through getting geologists of all lines to 

 give some attention to the subject, and through carefully con- 

 sidered and well executed special plans. Apparently the trend of 

 thought at the present time is in harmony with the needs. Some 

 assistance has already been rendered and more is planned by 

 speciaUsts in other lines. Physicists, chemists, biologists, and 

 others are ready to study marine deposition, the bottom loads 

 of rivers, cementation, dolomitization, problems connected with 

 the origin and accumulation of petroleum, and the geophysics 

 and geochemistry of the great sedimentary basins. Physiog- 

 raphers and climatologists will make their contributions. 



