264 Ancient Glaciers of New Zealand. 



boulders, indicate the former existence in that country, of 

 glaciers that have long since passed away, — and also the evi- 

 dences of former ice-action at the southern extremity of 

 South America and on the Falkland Islands, so well known 

 through the writings of Darwin and Agassiz, — we cannot 

 well escape the conclusion that they are all due to a common 

 cause. 



If we look for the reasons of the great variations of cli- 

 mate in the northern hemisphere, in astronomical changes, 

 as seems to be the increasing tendency among scientists, — 

 either in a change in the eccentricity of the earth's orbit, as 

 advocated by Prof. Croll, or in a variation of the angle of 

 the earth's axis with the plane of the ecliptic — we are obliged 

 to admit that the southern hemisphere has been subjected 

 to the same influences, and that the climates of the two hem- 

 ispheres must have undergone similar changes. 



It seems to us that the great extension of the glaciers in 

 these southern lands could not have been due altogether to 

 changes of elevation in the several countries, but, rather, 

 that the advance and retreat of these glaciers have been con- 

 trolled by the same — to us mysterious — laws, that in the 

 Tertiary period clothed Greenland with a varied and beautiful 

 vegetation, and replaced it in our times with immense gla- 

 ciers and fields of snow and ice. 



If the evidences of a glacial epoch in the southern hemi- 

 sphere seem too meagre for comparison with the corres- 

 ponding formations in our own country — where they cover 

 many thousand square miles — it is to be remembered that the 

 land itself is wanting in the former, on which to find the 

 inscriptions left by the old glaciers. In North America the 

 records of an ice-age reach as far southward as the fortieth 

 parallel. In the southern hemisphere nearly all the area in 

 corresponding latitudes, is occupied by the waters of the 

 ocean ; the only lands on which similar formations could 

 reasonably be expected, are the southern extremities of South 

 America and Africa, together with New Zealand and Aus- 



