interior was rendered more arid. 1 The plateau was afi'eeted 

 by desolating and cold winds, and the flora of the mild 

 Pliocene was unfitted to populate it. 



It will be seen at once that several factors came into 

 Operation during this stage. The law r of isolation came 

 into full force and the plants were called upon to rapidly 

 accommodate themselves to the new conditions or to 

 perish. Thus, instead of a grand and uniform southern 

 and central Eastern Australia flora as in the Pliocene, 

 three distinct types now exist, namely, a jungle, a plateau, 

 and a desert flora. Along the plateau the southern types 

 must have crept northwards until other natural barriers 

 were set, It must be remembered also that the plateaus 

 underwent refrigeration at a stage much later than the 

 Kosciusko Period, and this most likely induced a further 

 change of habit and form in those eucalypts which had 

 only just accommodated themselves to the plateau con- 

 ditions in the pre-glacial period. 



The site of Eastern Australia appeal's to have been 

 occupied at tbe close of Miocene time by a peneplain. At 

 a later period the peneplain surface was elevated and 

 definite channels of moderate deptb were cut in its surface 

 by the streams. Gold and tin were carried down from the 

 neighbouring hills and deposited in the coarse stream 

 gravels. Valuable "leads" were thus formed. The land 

 then sank and the channels became gradually filled with 

 sand, clay, pebbles, and lignite. Basalts at this stage 

 commenced to make their appearance, and flood after flood 

 of such basic lava buried thousands of square miles of the 

 country. The " leads" thus, in turn, became buried. Erosive 



dit.y is in. licit. ■■! by th>- p.vuli; 

 valleys have been .Vv.-h.p, ,1 in 



:'..:• '.. ' . . • 



iated and the streams disappear altogether in 1 



tinfall is not now sufficient to k-ep 



