BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 28, pp. 735-744 DECEMBER 4, 1917 



PEOBLEMS OF THE INTERPEETATION OF SEDIMENTARY 



ROCKS ' 



BY A. W. GRABAU 



(Presented before the Society December 29, 1916) 



CONTENTS 



Page 



Introduction 735 



The early and more recent investij^ators of sedinientaries 786 



Chemical deposits 739 



Organic deposits 739 



The older sedimentaries 740 



Change of f acies 740 



The older continental deposits 742 



Microscopic study of the sedimentaries 743 



The future of the science of lithogenesis 744 



Introduction- 



In the development of geological thought it was but natural that atten- 

 tion should at first be largely directed to dynamic phenomena and agents 

 and to the structures resulting from their activity, and that geologists 

 should be chiefly occupied with the elucidation of these structures. True. 

 the stratified rocks of the earth's crust have called forth speculation from 

 the very beginning, but mainly on account of their fossil contents. Ques- 

 tions of classification and correlation of the formations based on super- 

 position and on the inclosed organic remains have to a large extent en- 

 grossed the attention of the stratigrapher since the days of Lehman and 

 William Smith. That the characters of the rocks themselves could be of 

 any significance seems to have been realized by few, and these few con- 

 sidered such characters generally only from a special, often only a 

 mineralogical, viewpoint. More recently the phenomena of alteration or 



1 The first of a series of papers composing a "Symposium on the Interpretation of 

 Sedimentary Rocks." 



Manuscript received by tho Secretary of tbe Society .Taniiary 9, lf>17. 



LV — Bnt-L. Geol. Soc. Aim.. Vol. 28, 1910 (735) 



