I. 0. Russell — Glacial Records in the Newark System. 503 



Pleistocene glacial clays. The evidence that glaciers are not 

 necessarily accompanied by an extermination of mollnsks in 

 adjacent waters, is abundant. Besides, the hypothesis that 

 mollusks are absent from the Newark sediments on account of 

 glacial conditions, does not stand alone ; other explanations of 

 the same phenomena with many facts to support them have 

 been advanced. 



I have previously suggested that the great numbers of rep- 

 tiles, some of them of giganticsize, the bones and foot prints of 

 which occur in the Newark rocks, could not have lived in an 

 estuary or lake ' into which glaciers were discharging and on 

 which icebergs floated. Cold-blooded animals at the present 

 time among which we must look for the nearest living allies 

 of the " foot-print animals," are confined to warm regions ; 

 and there is no reason to suppose that this law of nature was 

 reversed during the Newark period. The swarms of reptiles, 

 both great and small, that lived at that time must have required 

 an abundant food supply ; this implies that the shores they 

 haunted were more like those of Florida than those of Green- 

 land at the present time. 



The fossil plants of the Newark are Araucarians, ferns, 

 equiseta and cycads. If these have any bearing on the ques- 

 tion of climate they indicate snb-tropical and not Arctic condi- 

 tions ; although there is no reason why they might not have 

 grown in proximity to glaciers. 



In regard to the marked modifications in the flora and the 

 extermination of the fauna of the Newark period, before the 

 deposition of the next succeeding formation, referred to by 

 Fontaine, we know that such changes have occurred at the 

 close of each important division of geological history and may 

 be accounted for in most cases by the imperfections in the 

 records. Breaks in the life records invariably accompany 

 breaks in stratigraphy. The assumption that these changes at 

 the close of the Newark period were due to glaciation, is mak- 

 ing an exception to a general rule, without facts to support it. 



The Coarse Deposits. 



It has been stated by Hitchcock and Fontaine, that the 

 coarse deposits of the Newark system belong at the top. These 

 statements lead Dana, as already cited, to the conclusion that 

 the Newark period ended in a semi-glacial era. If the coarse 

 deposit were confined to the top of the series, which as I shall 

 show below, they are not, it would scarcely follow that they 

 marked the close of the period, for the reason that deep erosion 

 has unquestionably taken place. 



But the coarse deposits are not confined to the top of the 

 series. Wherever the base of the system is exposed it is almost 



