Joseph Barrell. 261 



lead to the conclusion that "Climate is a factor com- 

 parable to _ disturbances of the crust or movements of 

 the shore-line in determining the nature and the varia- 

 tions in the stratified rocks of continental or offshore 

 origin, thus playing a part of large, though but little 

 appreciated, importance in the making of the strati- 

 graphical record.' ' 



Along with many other things, Barrell finds that 

 "While the varying powers of erosion and transporta- 

 tion are delicate stratigraphic indicators of climatic 

 fluctuations, the chemical and organic control accom- 

 panying the deposition are the more secure indicators 

 of the average climatic conditions/' 



Finally, what was the origin, environment, and sig- 

 nificance of the conglomerate and sandstone formations 

 intercalated between others of different nature? His 

 answer is that these coarse materials have three origins : 

 First, marine conglomerates and sandstones; second, 

 tectonic conglomerates and sandstones ; third, climatic 

 conglomerates and sandstones. 



"Changes in volume of ocean waters, earth move- 

 ments, and atmospheric activities are the three mixed 

 and fundamental causes by which the three classes of 

 deposits become possible, but the records which they 

 embody are largely distinct and independent. By 

 separating conglomerates and sandstones into these 

 three classes, the sedimentary rocks, therefore, present 

 a threefold record, the marine conglomerates giving that 

 of the variable relations of land and sea; the tectonic 

 conglomerates, the record of variable vertical uplifts; 

 the climatic conglomerates, the record of variable tem- 

 perature and rainfall. ' ' 



Barrell next took up for study "Some Distinctions 

 between Marine and Terrestrial Conglomerates/ ' the 

 gist of which he presented before the Geological Society 

 of America in 1908. Of this study there is printed only 

 a half-page abstract, but back of it lies over 200 pages 

 of manuscript completely rewritten in August, 1910, 

 and entitled "Marine and Terrestrial Conglomerates." 

 It is hoped that this paper may be printed before the 

 close of 1920. In the abstract he states that "The truly 

 terrestrial forces produce vastly more gravel, spread it 

 far more widely, and provide more opportunities for 

 deposition than do the forces of the littoral zone." 



Am. Jour. Sci.— Fourth Series, Vol. XLVIII, No. 286.— October, 1919. 

 19 



