66 GEOLOGICAL NOTES ON KOSCIUSKO, 



It would be presumption on our part to express any opinion 

 on this important point. At the same time, in view of the 

 evidence lately obtained in South America, Tasmania and Kosci- 

 usko, it might be as well for the New Zealand geologists to 

 enquire further into the interpretation of their evidence. In 

 Kerguelen Island the snow line would appear to have been 

 formerly (in late Cainozoic time) at least 1,000 feet lower than at 

 present, and in South America several thousand feet lower, 

 though, as far as we can learn, the exact amount has not yet been 

 calculated. In South America, moreover, there is evidence of at 

 least two distinct epochs of glaciation. 



(h) In our opinion, even if the case of New Zealand, as being 

 still sub judice, be omitted from consideration, the general 

 evidence points to a universal glacial period, of at least two 

 phases or epochs, in the Southern Hemisphere. If these pro- 

 visional deductions are correct, at least two very important 

 questions suggest themselves for further investigation: — 



(1.) Did the glaciation of the Southern Hemisphere lead to 

 definite biological migrations similar to those due to the " Great 

 Ice Age " in the Northern Hemisphere "? 



(2) If the glaciation of the Southern Hemisphere was syn- 

 chronous with that of the Northern Hemisphere, as now seems 

 probable, was it due to some great cosmic atmospheric cause, as 

 suggested long ago by Tyndall, such as the variation of the 

 amount of COg in the earth's atmosphere, as lately investigated 

 by Dr. Arrhenius and Mr. Hogbom,* and advocated by 

 Professor Chamberlin ? f 



* Phil. Mag., April, 1896, pp. 287-276, and Journ. Geology, Vol. vii. 

 Nos. 6, 7 and 8, 1899. 



t In connection with this one of us (Prof. David) would suggest that the 

 greater cold at present of the Southern Hemisphere as compared with the 

 Northern may be due to the former having a thinner blanket of air than the 

 latter. The data on this point at present are insufficient, of course, for 

 generalisation, but as far as they go are in favour of the view that atmospheric 

 pressure, and consequently atmospheric thickness, is less in the Southern 

 than in the Northern Hemisphere. 



