Dr. Croll's Theory of Glacial and Warm Periods. 107 



covered with any amount of vegetation worth mentioning, 

 and, moreover, the sides of the mountains on the shore 

 itself frequently present perpendicular sections, which every- 

 where expose their bare surfaces to the investigator. The 

 knowledge of a mountain's geognostic character, at which 

 one in more southerly countries can only arrive after long 

 and laborious researches, removal of soil and the like, 

 is here gained almost at the first glance ; we have never 

 seen in Spitzbergen, or in Greenland, in these sections 

 often many miles in length, and including, one may say, all 

 formations, from the Silurian to the tertiary, any boulders 

 even as large as a child's head. No strata containing 

 boulders are to be found in the Polar tracts previously to 

 the middle of the tertiary period. 



" Since, then, both an examination of the geognostic 

 condition, and an investigation of the past flora and fauna 

 of the polar lands, show no signs of a glacial era having 

 existed in those parts before the termination of the miocene 

 period, we are fully justified in rejecting, on the evidence of 

 a clear observation, the hypothesis founded on purely 

 theoretical speculations, which assumes the many times 

 repeated alternation of warm and glacial climates, between 

 the present time and the earliest geological ages" (id. 531-2). 

 The convergence of evidence is irresistible, therefore, in 

 regard to the absence of substantial evidence of alternating 

 climates in the older deposits, and the best proof of this is 

 the way in which the advocates of this theory virtually 

 neglect the vast field of inquiry which lies open to them in 

 the whole range of sedimentary strata from the cambrian 

 to the end of the tertiary period, and converge their artillery 

 upon the testimony of the so-called glacial beds themselves) 

 the latest chapter only in geological history. 



In regard to the evidence of so-called glacial beds, I wish 

 to say most emphatically that it is most unsafe and most 

 dubious. We have not yet found a key by which we can give a 



