GEOGRAPHICAL I'MTV OF K \STKRN WSTKALIA. 457 



Along side of this we may place the accounts of Pliocene 

 and Pleistocene history in North America as interpreted 

 by American authorities. Among American authorities 

 the Ozarkian or Sierran Period is considered either as the 

 close of the Pliocene 1 or the commencemnt of the Pleisto- 

 cene." Le Conte and others favoured a Pleistocene age 

 for it. According to these authorities a study of Western 

 North America points to the conclusion that (1) during the 

 Pliocene, wide valleys almost of peneplain dimensions in 

 places were formed along the Pacific area, that (2) at the 

 close of the Pliocene an enormous uplift and faulting 

 movement took place, and that (3) the profound gorges 

 of the Sierras, of the Rocky and Selkirk Mountains, and of 

 the Colorado Canon of Arizona were the work of Sierran 

 (Pleistocene) activities. 



If we now look at this from a hroader or " Pacific" point 

 of view it will he seen that physiographieally our "Newer 

 Volcanics " may be placed in the Pliocene. The Eastern 

 Australian coast is roughly of the Pacific type ; it borders 

 the Pacific, while the stage of dissection of both the "Newer 

 Volcanics" and of the associated plateau surfaces is similar 

 to that assigned to late Pliocene activities in Western North 

 America. The Kosciusko period 3 also presents great 

 similarities to the Sierran Period in America, and the later 

 stage of plateau dissection arrived at by each area is almost 

 identical. Even the subsidence during the Human Period 

 for each area is similar in appearance. It would appear 

 in fact that "Pacific" conditions obtained during the 

 Pliocene and Pleistocene periods. 



Conclusions.— It will now be interesting to discuss briefly 

 the physical and biological significance of the late and 

 Post-Tertiary activities in Eastern Australia. 



' Journal of Geology Vol. .win. 1010, No. 3. p. 227. 



» Chamn.-rl-: ; - . ■-! OXf •- ijy, V. ! in. pp. 311-318. 



8 Believing that " Diastrophisui e !-.tion" the 



writer regards the "Kosciusko Period " as the movement which closed 

 the Tertiary and ushered in the Pleistocene. 



