CHAPTER X. 



THE PHYSICAL CAUSE OF MILD POLAR CLIMATES. — 



Continued. 



Climate of the Tertiary period, in so far as affected by Eccentricity. 

 — Evidence of Alternations of Climate. — Were there Glacial 

 Epochs during the Tertiary period ? — Evidence of Glaciation 

 during the Tertiary period. 



Climate of the Tertiary period, in so far as affected 

 by Eccentricity. — If the foregoing conclusions are 

 correct, it is not difficult to infer what would be the 

 probable character of the climate of the Tertiary 

 period, in so far as that climate was affected by- 

 eccentricity. As is truly remarked by Mr. Wallace, 

 the eccentricity during the past three million years 

 has been almost always much higher than it is now. 

 It will consequently follow that very considerable 

 portions of the Tertiary age would consist of alternate 

 comparatively cold and exceedingly warm and equable 

 periods. These may be said to correspond to the cold 

 and warm periods of the Glacial Epoch ; but, of course, 

 they could in no sense be called glacial and interglacial 

 periods ; for the cold of the cold periods would not be 

 such as to produce permanent ice, while the heat and 

 equability of the warm periods would far exceed that 

 of the interglacial periods. 



Evidence of Alternations of Climate, — That such 

 oscillations occurred during the Tertiary period 

 seems to be borne out by the facts of geology and 



