CLIMATE AND TERRESTRIAL DEPOSITS 621 



First. Marine conglomerates and sandstones, due to marine planation and 

 transportation, enabled to reach wide horizontal extent over shallow seas 

 through crustal movements shifting the zone of wave and current action. 



Second. Tectonic, conglomerates and sandstones, due to subaerial erosion, 

 owing to a steepening of the river slopes, either from mountain making, crustal 

 warping, or subsidence of the ocean level. 



Third. Climatic conglomerates and sandstones, due to climatic change, with- 

 out necessarily any new and accompanying crustal movement, producing a 

 shifting of the region of accumulation of gravel or sand and a resulting con- 

 trast in coarseness, in color, and in chemical composition with the underlying 

 and overlying formations. It is by means of the associated features that 

 climatic conglomerates are to be distinguished from those of tectonic origin. 

 For these two to be sharply separable in nature, the climate must remain stable 

 during an epoch of crustal movement and, vice versa, earth movements must 

 be supposed quiescent during a time of climatic change. As tectonic and cli- 

 matic movements may be intermixed, there may often be a dual cause of con- 

 glomeratic formations. 



The establishing of a class of climatic conglomerates involves the conception 

 of the shifting location of deposits (in space) during an epoch of crustal quiet 

 as being of the same geologic importance as the varying pulses of erosion 

 (tlirougli time) due to tectonic movements. 



In conclusion, it is seen that by means of conglomerate or sandstone forma- 

 tions the important changes are recorded in each of the three fundamental 

 environments of the lands, namely, the relations to the surrounding seas, the 

 topography which forms their surfaces, and the climates which envelop them. 



ORIGIN AND SIGNIFICANCE OF THE MAVCH CHUNK SHALE 

 BY JOSEPH BARKELL 



This paper is printed as pages 449—476 of this volume. 

 The two foregoing papers were discussed by D. White, B. Willis, I*'. 

 Huntington, A. W. Grabau, W. M. Davis, and the author. 



The next paper was 



RIVER SEDIMENT AS A FACTOR IN APPLIED GEOLOGY 

 BY W J MC GEE 



The last paper of the afternoon in this section was 



ORIGIN OF OCEAN BASINS IN THE LIGHT OF THE NEW SEISMOLOGY 

 BY WILLIAM HERBERT HOBBS 



This paper forms pages 233-250 of this volume. 



The second section met with George P. Merrill in the chair and H. M. 

 Ami acting as secretary. 



IJII — Bull. Geol. Soc. Air., Vol. 18. lOOC. 



