Oh. XIII.] 



AFI 



2 9 9 



me 



we are that a change of 



land in high latitudes than at present, 

 were in excess, we are more certain that the change alluded 

 to would intensify the cold than 

 excentricity would have the same effect ; for the last-men- 

 tioned conclusion depends upon the soundness of the hypo- 

 thesis that, in spite of the annual supply of solar heat being 



summer 



come the increased winter's cold whenever the latter gives 

 rise to a much greater snow-fall. 



If the sketch which we have given in the tenth and 

 eleventh chapters of the former states of climate revealed 

 to us by palseontological research be an approximation to 

 the truth, it will at once be seen that glacial periods have 

 not been perpetually recurring in the northern temperate 

 zone, as they ought to have done were a large excentricity 

 alone sufficient, apart from the cooperation of all other causes, 

 to intensify the cold of high latitudes. It was shown that 

 the flora and fauna do not exhibit signs of violent revolutions 



from hot to cold and from 



On the con- 



ms 



om 



opposed to the intercalation of glacial epochs corresponding 

 in importance to that of Post-pliocene date. 



During the 



Carboniferous Period there must have been a long suspen- 



tem 



of cold such as we now experience. An equable climate 

 must have endured for a lapse of centuries, sufficient to 

 allow several great cycles of excentricity to be gone through. 

 But we do not find in strata of that age 15,000 feet thick 

 in Nova Scotia any proofs of such intercalated glacial epochs. 

 The peculiar vegetation of the coal was persistent throughout 



greater 



sediment 



was buried on the spot where it had grown."* 



The absence of recurrent periods of cold is perfectly 



explicable, if I am right in 



concluding that 



they can 



only be brought about by an abnormal quantity of land 

 in high latitudes ; for under ordinary geographical conditions 





! 



* 



_ 



* See Elements of Geology by the Author, p. 482. 



