BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 31, PP. 411-418 NcVtMBER 30, 1920 



PHYSICAL AND GEOGEAPHIC CRITEEIA IN THE STUDY 

 OF SEDIMENTARY DEPOSITS ^ 



BY E. W. SHAW 



{Read before the Society Decemher 31, 1919) 



CONTENTS 



Page 



Extent of the field 411 



Objects of research 412 



Concerted efforts 412 



Classes of investigation 413 



Mechanical analyses and their diagrammatic representation 414 



Reference collection 415 



Need of classification and nomenclature 416 



Areal surveys 416 



Laboratories and equipment 417 



Some of the problems 418 



Extent of the Field 



Apparently by common consent the present symposium covers the study 

 of the formation of sedimentary deposits from the immediate or even 

 remote origin of the component materials to the destruction of the de- 

 posit — that is, not only sedimentation, or the process of deposing sedi- 

 ment, but also the nature of the ancestral rocks and the complex processes 

 of weathering, plucking, transportation (direct, interrupted, repeated, 

 and reversed), deposition (usually repeated), diagenesis, and all the other 

 processes in the entire cycle of transformation from igneous or meta- 

 morphic rocks to metamorpliic or even igneous rocks. It includes the 

 multitude of physical processes, agents, and results involved in the for- 

 mation of a clastic deposit; and most sedimentary rocks are to some de- 

 gree clastic. The field thus overlaps that of erosion, particularly with 

 regard to transportation. 



Manuscript received by the Secretary of the Society February 14, 1920. 

 Tublished by permission of tl)e Director of the U. S. Geological Survey. 

 This paper is one of a series composing a symposium on sedimentation. 



(411) 



