1S6 E. ('. Andrews — The Geological History of th< 



repeated elevations with stream revivals. During one or more 

 of the Tertiary divisions of time, especially the Miocene, the 

 land appears to have sunk somewhat with the formation of lake- 

 like expanses along the stream courses and the burial, later, 

 of deep river deposits beneath basalt floods covering thousands 

 of square miles in Eastern Australia. This led to great modi- 

 fications in stream drainage, but the great and dominating 

 lesson of repeated stream revival cannot be overlooked, the 

 modifications due to basalt floodings being only an incident in 

 the establishment of the great geographical unity of Eastern 

 Australia in Tertiary and post-Tertiary time. 



Two glacial visitations at least during the Pleistocene haAe 

 been recorded for Australasia. 7 As the various geographical 

 changes were contemplated in Australia, such as the increase in 

 height of the plateaus, the approach of the Glacial Period, and 

 the succession of the milder interglacial periods, it may be 

 understood how vast a change such influences would have 

 induced in the flora of East Australia and of New Zealand, espe- 

 cially in the extinction of weak types and the saltation of 

 vigorous and aggressive genera such as Eucalyptus, Acacia, 

 Veronica, Pultenwa, and Coprisma. 



(6) The Transport of Plants and the Distribution of Mammals. 



(1) The Transport of Plants. 



By sea currents, by birds, by winds. The works of Charles 

 Darwin, Guppy, Schimper, Hemsley, and others, are full of 

 instances showing the great power of transportation of plants 

 by the agencies here enumerated, and not only so but of the 

 vitality of many seeds thus transported. The example of 

 Krakatoa populated with many species of plants between the 

 years 1883 8 and 1908, is very significant in this connection. 

 If Krakatoa, a small island, has received such a large flora 

 as it possesses at present from the action of currents, birds, 

 and man, what may have been accomplished during the progress 

 of ages in the way of plant transport by similar agencies from 

 one great land block to another, such as from America to 

 Africa, to Australia, or to ISTew Zealand? Here again we 

 have also the cumulative action of time and the long-continued 



7 David (T. W. Edgeworth). Geological Notes on Kosciusko, -with special 

 reference to the evidence of Glacial Action, Proc. Linn. Soc. N. S. Wales, 

 vol. xxxiii, pp. G57-660, 1908. David (T. W. Edgeworth), Pittman (E. F.), 

 and Helms (R.), Geological Notes on Kosciusko, Proc. Linn. Soc. N. S. 

 Wales, xxvi. pp. 26-27, 1901. 



8 Ernst, "New Flora of Krakatoa," Cambridge University Press, 1908. 

 Quoted from letter by Dr. H. B. Guppy. 



