BY R. M. JOHNSTON, P.L.S. 203 



marine beds of the Wangaiiui system, an interval which 

 closely corresponds witli that which divides the Palseogene 

 and Neogene epochs in Australia and Tasmania. Thus, 

 in his " Sketch of the Geology of New Zealand " (Quart. 

 Journal Geol. Soc, May, 1885, p. 211), Professor Hutton 

 states, " the former great extension of our glaciers was 

 caused by greater elevation of the land^ during the 

 interval between the Pareora system and the marine beds 

 of the Wanganui system." He adds, however, that com- 

 plete proof is wanting owing to the absence of fossils, as 

 in the raised terrace drifts of Tasmania. 



It may be well to state, however, that the indications 

 pointing to a glacial period in Australia have been referred 

 by some geologists to causes which introduced more 

 recently the glacial epoch in Europe and North America, 

 and that the traces of glaciers on the Alps of New Zealand 

 and Austraha were deemed by them to be the counterpart 

 of effects produced during the glacial epoch in the 

 northern hemisphere, and attaining their maximum there 

 during the Pleistocene period. 



But although it be admitted that the primary cause of 

 the glacial epoch in the northern hemisphere in the 

 Pleistocene period may be due to the high phase of eccen- 

 tricity of the earth's orbit in combination with winter in 

 aphelion — the effect of precession — it does not necessarily 

 follow that the extreme effects of glaciation have been 

 produced in both hemisjDheres or in different epochs by the 

 recurrence of such astronomical causes alone. It is admitted 

 that warm ocean currents have such an important bearing 

 upon the question that, if they were not debarred to a 

 great extent from the hemisphere specially affected by the 

 astronomical causes referred to, glaciation of an extraor- 

 dinary character would not be appreciable. Now the 

 preponderance and the nature of the distribution of the 

 land in the northern hemisphere render the latter more 

 liable to the obstruction or diversion of the warm equatorial 

 ocean currents, produced by geographical changes, while, 

 with the smaller extent of elevated land and its insular 

 position, the southern hemisphere would be comparatively 

 unaffected. It is also conceivable that during the Cre- 

 taceous and early Tertiary period the greater part of the 



^The marine beds attain an elevation of more than 2000 feet near Najiier. 



