1810 
president’s address. 
on being pushed to its legitimate consecpience developes an 
absurdity, an impossibility or an extreme improbability, one 
naturally turns back to the premises. And so it becomes worth 
while to examine whether there are any substantial grounds for 
the supposition of contemporaneous glacial action in India, Africa 
and Australia during the Upper Carboniferous (or Oarbonifero- 
Permian) period. 
It will from the foregoing be understood that my use hereafter 
of the word “glacial” does not imply any belief in a general 
glaciation or ice sheet, but only in the existence of glaciers in 
mountain districts, of icebergs floating in marine currents, or of 
river ice swept down in spring floods. 
I do not quite understand why every statement as to Glacial 
periods, or periods of very considerable local glaciation, older than 
the Pleistocene should be received with so much distrust and 
ho.stile cavil as is the case at present with English Geologists. 
For at any term during which the fossiliferous .sedimentary rocks 
were being deposited Glaciers would surely be formed wherever 
the conditions mentioned above were favourable. And these 
conditions depend both upon general astronomical causes, and upon 
Geographical modifications which may be either local or general. In 
the same way, under certain Geographical and Astronomical com- 
bined variations, a moist and equable climate may have prevailed, 
and may again prevail in Arctic and Antarctic regions, though 
not in both at the same time. There seems to me no sufficient 
ground for assuming that even during the remotest period of 
recorded life the internal or I’esidual heat of the globe has had 
any appreciable effect upon the distribution of living forms upon 
its surface. 
Dr. Croll has enumerated (Climate and Time, p. 292 seq.) a great 
number of supposed instances of both Glacial and Interglacial 
periods, beginning with the Cambrian ; and, after making all 
reasonable allowance for bias in the mind of the writer or of his 
authorities, there must surely remain a basis of truth in the concur- 
rent opinion of so many observers. I may add that Mr. Wilkinson 
