SHAW: SEDIMENTATION 519 



who have either made valuable observations in connection with 

 other work or who have dropped their other work for a time while 

 they undertook a special study of sediments. 



Especially noteworthy advances in the study of present-day 

 sediments have been made during the last decade or two. Mur- 

 ray and others have collected much information concerning the 

 great ocean deeps. Thoulet gave us a detailed map showing 

 the areal distribution of sediment over a portion of the sea floor. 

 Engels experimenting with an artificial stream analyzed pro- 

 cesses of alluviation. Gilbert deduced, from a series of experi- 

 ments, certain fundamental laws concerning fluviatile transporta- 

 tion of sand and gravel. 



Barrell gave us a philosophical discussion of the conditions 

 and processes involved in the accumulation of Uttoral deposits. 

 Kindle has observed and recorded diagnostic features of various 

 kinds of deposits. Udden has presented the results of many 

 years of study of the mechanical constitution and peculiarities 

 of the main classes of sediments. Goldman has given us the 

 results of his investigations of sources of certain sediments and 

 the diagenesis of others. 



Recently T. W. Vaughan has put into operation a plan for 

 coordinating the energies of those principally interested in sed- 

 iments, and in response to his request they have submitted 

 memoranda which have been transmitted to the National Re- 

 search Council. The main feeling behind the movement is ex- 

 pressed in Vaughan 's memorandum in the following words: 

 "As the factors entering into both the origin and deposition of 

 sediments are so diverse and so widely distributed it is imprac- 

 ticable for any one man, any small group of men, or any organiza- 

 tion whose activities are really limited to cover the field." 



Some quotations from the replies will be of interest. Barrell, 

 obviously impelled mainly by his interest in earth history, says 

 by way of introduction to his ''Project J or a study oj sedimenta- 

 tion,'' dated January, 191 9: 



"If the interpretation of the climatic and physiographic his- 

 tory of the earth, as based on the nature of the sedimentary 

 rocks, is to progress along Hues now opened up, it is neces- 



