426 A YEAR IN BRAZIL. 



to the deposit of glacial drift. M. Liais explains that the action 

 of vegetation, animals, insects, dry and wet seasons, wind, etc., 

 are sufficient to destroy the evidence of stratification in these 

 cases. Professor .Drummond's article on the " Work of the 

 Termites," * in which he claims that these insects carry on in the 

 intertropical regions a similar work to that of the earthworms in 

 the temperate zones, at least affords a comfirmation of M. Liais's 

 view ; and I have alluded to the parti-coloured heaps which they 

 construct, and which forms perhaps the most noticeable feature of 

 the campos. This proves from how many different strata even one 

 nest is made, and the burrowing of these insects, with the cabec,udo 

 ants (Atta cephalotes\ and the armadillos, must necessarily destroy 

 all traces of stratification to a considerable depth. 



" Mr. Belt calculates that the vast amount of water abstracted 

 from the ocean and locked up in mountains of ice around the two 

 poles would lower the general level of the ocean about two thousand 

 feet. This would be equivalent to a general elevation of the land 

 to the same amount, and would thus tend to intensify the cold; and 

 the subsidence of the ocean would produce a tract of lowland of 

 an average width of some hundreds of miles, added to the whole 

 east coast of Central and South America. This tract would no 

 doubt become covered with forests as it was slowly formed, would 

 enjoy a perfectly tropical climate, and would thus afford an 

 ample area for the continued existence and development of the 

 typical South American fauna ; even had the glaciers descended 

 in places so low as what is now the level of the sea." f 



I would suggest that a difference of two thousand feet in the 

 level of the highlands above the sea would not suffice for the 

 production of the supposed glaciers. This presumption of a glacial 

 period in the tropics presents great 'difficulties. First, a vast 

 expanse of collecting ground is necessary at a considerable alti- 

 tude for the neve to consolidate into glaciers at a lower level ; 

 secondly, it requires for a very prolonged period a very low 

 temperature in the intertropical regions, which would presumably 

 mean such an intense cold in what are now the temperate climes 

 that no life could there exist. I cannot see that either of these 



* Good Words, May, 1885. 



t "Geographical Distribution of Animals," vol. i. p. 151, A. R. Wallace. 



