204 TERTIARY ROCKS OF AUSTRALASIA, 



western equatorial current of the Pacific Ocean swept 

 southwards through the then broad open mesial gulf 

 dividing Eastern and Western Australia, and the diversion 

 of this powerful warm current upon the rising of the land 

 towards the close of the Falceogene period may have had 

 a larger influence in lowering the local temperature than 

 that due to the astronomical causes referred to. 



The effect of the influence of warm oceanic currents in 

 equalising or modifying local climatic effects, however 

 produced, cannot well he over-estimated in regions open 

 to their passage. To them we owe, as Dr. James Croll, 

 Wallace, and others have so admira])iy shown, all the 

 amelioration of climate in regions which otherwise would 

 be uninhabitable. Wallace, in his very remarkable work, 

 "Island Life," p. 183, states: "Owing to the peculiar 

 distribution of land and sea upon the globe, more than its 

 fair proportion of the warm equatorial waters is directed 

 towards the western shores of Europe, the result being 

 that the British Isles, Norway, and Spitzbergen have all 

 a milder climate than any other parts of the globe in 

 corresponding latitudes. That such considerations must 

 have great weight with those who are directing their 

 attention to the possibility of a glacial epoch in the Southern 

 Hemisphere in later times corresponding to that of the 

 Northern Hemisphere during the Pleistocene period is 

 most certain ; for, as Mr. Wallace explicitly states (p. 201, 

 loc. cit.), " a concurrence of favourable geographical con- 

 ditions is essential to the initiation of glaciation "... 

 and, he continues : " When, however, geographical con- 

 ditions favour warm Arctic climates — as it has been shown 

 they have done throughout the larger portion of geological 

 time — then changes of eccentricity, to however great an 

 extent, have no tendency to bring about a state of glacia- 

 tion, because warm oceanic currents have a prepon- 

 derating influence, and without very large areas of high 

 . land to act as condensers no perpetual snow 

 is possible, and hence the initial process of glaciation does 

 not occur." 



Accordingly, from the very smaller proportion of elevated 

 land in the Southern Hemisphere, and from the impro- 

 bability of the equatorial ocean currents having been 

 appreciably excluded at any time, owing to the absence of 

 connected land barriers, it is reasonable to infer that the 



