T. C. Charriberlin— Diversity of the Glacial Period. 199 



that the interval is emphasized by notable vegetable accumu- 

 lations, and supported by the strong analogy of the Great Basin 

 phenomena, the whole combination takes on a strength which 

 seems to me altogether irresistible. 



While the evidence from plant and animal remains found 

 in the interglacial beds in America has not yet reached a full- 

 ness and definiteness which render it altogether decisive regard- 

 ing the climate of the interglacial intervals, though it indicates 

 something less than a glacial climate, the evidence of this class 

 in Europe, a summary of which is given by Dr. Geikie in the 

 paper already referred to, appears to me entirely decisive, 

 unless the integrity of the observations can be overthrown. 

 The demonstration of a climate in Northern Europe, compar- 

 able to the present, seems to carry with it the necessary con- 

 clusion that glacial conditions were essentially as remote then 

 as now. It seems to me idle to cite the fact that temperate 

 faunas and floras now exist in the vicinity of glaciers within 

 the temperate zone, for these are mere local phenomena and 

 do not stand related to the general climate of the region, as the 

 great ice sheets of glacial times must have done. The fossil 

 evidence of the acknowledged glacial epoch shows Arctic con- 

 ditions. On the same basis of reasoning, a temperate fauna 

 and flora show the absence of glacial conditions. 



When, therefore, to the strong cumulative physical evidence 

 in America and the similar physical evidence in Europe, there 

 is added the array of organic evidence that has now grown 

 large, it seems to me the case approaches demonstration, so far 

 as the general fact of a great interval or intervals is concerned. 

 To fail to accept this, at least as a working classificatory basis, 

 is to do violence to the highest interests of science. 



The history of this question I apprehend, will be very analo- 

 gous to that of paleontological research. In the earlier stage, 

 investigators were satisfied with very general delineation and 

 rude groupings of forms. But, with the progress of the sci- 

 ence, more and more critical scrutiny of likenesses and differ- 

 ences was found requisite, and closer and closer specific and 

 varietal distinctions were drawn. This tendency at length 

 became excessive and the multiplicity of divisions was pushed 

 beyond the actual phenomena. The enlargement of collec- 

 tions then began to bring together many species by inter-gra- 

 dations, and the elimination of false species resulted. But yet 

 certain species stand clearly differentiated from all other species 

 and unquestionably will continue to stand. The gaps between 

 them can only be filled by tracing them far back in geological 

 time. So I think it may be with the divisional effort in the 

 glacial field. We are very likely to push differentiation to 

 excess in the stage we are now approaching, and to recognize 



