840 PRESIDENTS ADDRESS. 



subsidence, with tlie result tliat, to my thinking, the phenomena 

 <are capable of much more satisfactory explanation on a solid globe 

 than on an encrusted fluid one." 



Changes of Climate. 



The changes of climate, which occurred in the Carboniferous 

 period, if the phenomena are rightly interpreted, are much more 

 extraordinary than those of the Pleistocene when the so-called 

 Glacial period or periods set in, for the latter appear to have 

 been chiefly due to a general cooling of the poles and a con- 

 sequent enlargement of the ice caps. The latter phenomena are 

 visible both in the northern and southern hemispheres, whereas 

 the glacial action which appears to be traceable in the Carbon- 

 iferous period extended over Southern India, South Africa, 

 Australia and South America only. At this time Dr. W. T. 

 Blandford (Part 2, Vol. xxix. of the Records of the Geological 

 Society of India) says that these countries formed a continent, 

 judging from the peculiar flora which characterises them. In 

 each case a boulder bed " undoubtedlj'' glacial in origin" has been 

 found associated with them. Dr. Feistmantel states that the 

 Lepidendron flora was swept away at the ushering in of the new 

 conditions and gave way to the Glossopteris and Gangamopteris 

 flora. He shows that a shifting of the pole would not account 

 for the new conditions, as on the opposite side of the earth the 

 vegetation remained unaffected, and the difiiculty of imagining so 

 large an area of the earth's surface influenced by the advance of 

 the polar cap is all the gi-eater seeing that since the writing of Dr. 

 Feistraantel's report South America has been added to the territory. 

 Dr. Blandford points out how this area must have been cut off from 

 the rest of the world by sea, so that once the vegetation had 

 changed it was preserved from immigration of the old flora; but 

 how did it become changed? could it have been by cold, seeing 

 that the other side of the earth was unaffected? The phenomena 

 of stranded boulders, groovings and scratchings are extraordinarily 

 like what glaciation produces, but can they only be accounted for 

 by ice? Assuming the glacial phenomena to have existed in 



