Dr. CroWs Theory of Glacial and Warm Periods. 95 



phenomena in the northern hemisphere are obvious enough. 

 They need no microscope to discover them. They literally 

 present themselves in every cubic yard of soil. Everywhere 

 where they occur, boulders, or glacial clays and sands, or er- 

 ratics, or arctic shells, are to be found, while mammillated rocks 

 and scratches, etc., etc., are found everywhere on high ground. 

 Nothing is more patent and nothing more obvious. This 

 being so, it is clear that if the cause is a similar and recurrent 

 one in either hemisphere, as urged by Croll, and those who 

 maintain Croll's position, we must be able to support it, not 

 only from one hemisphere but from the other. We cannot 

 doubt that the very same cause, operating on the southern 

 hemisphere, must have had the same or similar results to that 

 operating on the northern one. We oughttofindinthesouthern 

 hemisphere, therefore, a state of things corresponding to that 

 which is such a marked feature of the northern hemisphere, 

 namely, a vast development of glacial phenomena, such as 

 polished and rounded rock surfaces, striae, erratics, and drift, 

 not limited to a few valleys once occupied by large glaciers, but 

 spread over an enormous area, and needing no microscope to 

 discover them. Where are we to look for anything like this 

 in the southern hemisphere, and especially in that part of 

 the southern hemisphere which forms the antipodes to the 

 North Atlantic district? We undoubtedly have at this 

 moment with no excessive eccentricity a remarkable develop- 

 ment of cold at the South Pole. With greatly increased 

 eccentricity, if Dr. Croll's arguments are good, this ought to 

 have been greatly increased, and especially ought it to have 

 been so in the southern hemisphere, where there is so much 

 water, and, consequently, so much evaporation. But where 

 are we to look for it ? In South America we no doubt have 

 something resembling what we can find in boreal America : 

 boulders, erratics, and scratched rocks, which have been 

 described by Darwin, Agassiz, and others. But what of 

 New Zealand, our antipodes, Australia, and South Africa ? 



