• Dr. Croll's Theory of Glacial and Warm Periods. 109 



served also that there is no evidence in North America of an 

 interglacial period in the sense of the one supposed to have 

 existed in Europe" {id.). 



Mr. Searles Wood, junior, an explorer of great ex- 

 perience says, that with the exception of one warm interval 

 marked by beds containing cyrena fiuminalis, he has "not 

 been able to discover any indication of those alternations of 

 warm and cold climate which form an indispensable part of 

 the eccentricity theories of Adhemar, Croll, Murphy and 

 others." "In the case of North America there has also been 

 a failure altogether, on the part of the geologists of that 

 country, to detect evidence of more than one alteration of 

 climate during the glacial period." {Geol. Mag. "Decade II." 

 X. 294). 



The evidence of life is still more unsatisfactory. Professor 

 James Geikie, in his address at Newcastle, recurred to views, 

 which I thought were extinct, about the deposits containing 

 reindeer and other boreal animals being of a different age to 

 those containing austral forms. How can this be, when all 

 over France, Germany, and South Britain we not only find 

 reindeer bones mixed with those of the hyaena ; but as 

 Professor Dawkins has shewn, gnawed by hyaenas, when 

 we meet with the leaves of the arctic willow mixed 

 with those of the canary laurel and the fig, to mention 

 only two facts out of a great many which may be 

 found collected in a book which I have published, entitled 

 "The Mammoth and the Flood." There is no evidence 

 known to me which can be derived either from the animal 

 or the plant remains in the drift deposits which would 

 justify recourse to a theory of alternating climates, and the 

 cases which have been cited are, it seems to me, entirely 

 irrelevant. No doubt mammoth's teeth and remains of 

 other animals, his contemporaries, have sometimes been 

 found over and sometimes under boulder clay. This fact, 

 no doubt, needs explanation, and can, I believe, be com- 



