president's address. 571 



out of the enormous amount of rock that had been broken up and 

 removed during the erosion of the broader part of the valley, 

 whereas the rich contents of the lead having been protected from 

 redistribution into the new and perhaps deeper channel, the 

 latter contains only the quantity of gold derived from the dis- 

 integration of the smaller bulk of rock represented by the 

 narrow dimensions of the bottom of the valley. This subaerial 

 denudation has continued from the early Tertiary period to the 

 present day, and we find here and there upon the furrowed 

 slopes of the Great Dividing Eange remnants of the fluviatile 

 deposits which accumulated at various times during that long 

 period. Besides the metallic substances derived from the de- 

 nuded formations, these accumulations, consisting of pebbles, 

 sand, mud and clay, contain vestiges of the animal and vegetable 

 forms which successively lived upon this ancient land, and from 

 which the existing fauna and flora have been developed. Thus in 

 the Pleistocene deposits we have bones of some of the existing 

 species of animals mingled with those of the extinct gigantic 

 diprotodon, macropus, megalania, etc., for the description of 

 which we are chiefly indebted to Sir Richard Owen. In the 

 Pliocene occur fossil fruits, described by Baron Yon Mueller, and 

 leaves and stems of trees, with a fresh water unio, which has been 

 described by Mr. R. Etheridge, junr. F.G.S. ; and in the lower 

 Miocene or Eocene, we have abundance of fossil leaves, some of 

 which have lately been examined by Baron von Ettingshausen, 

 who has given the following interesting particulars in the 

 Geological Magazine for April 1883 : — 



The fossil plants collected by Mr. J. K. Hume from Dalton, 

 and sent by Mr. C. S. Wilkinson, Government Geologist of New 

 South Wales, to Mr. Robert Etheridge, junior, at the British 

 Museum, "belong to 27 species, 21 genera, and 17 families. The 

 species I have under examination are all new ; of the genera only 

 two (Ficonium and Pomaderrites) are new, whilst the others occur 

 both in the Tertiary formation of Europe (19), North America 

 and North Asia (13), Java (4), Sumatra (3), and Borneo (3). 

 Only six of the genera are contained in the living flora of 



