1226 president's address. 



these so-called periods ; like all other epochs they are as inseparable 

 and continuous portions of the earth's history, as are the individual 

 " years " of a man's life. We must however make certain divisions 

 for the purpose of recording in their order of succession the events 

 and changes which have brought about the natural history phen- 

 omena which it is the especial work of this Society to study. 



During the periods referred to the main physical features 

 of the country have remained pretty constant. There have 

 been no great local disturbances ; our most recent volcano, 

 Mount Canobolas, near Orange, whose conical summit 4565 

 feet above the sea level towers above the surrounding 

 country, had already ceased to cloud the atmosphei'e with its 

 steam and dust. The Great Dividing Range, with all its main 

 valleys, and the low lying country of the interior, presented the 

 same general outline at the commencement of the Pleistocene 

 period that we observe at the present clay. 



All these principal physical features were shaped prior to the 

 Pleistocene period by different causes — volcanic irruptions at 

 various times, faultings, and the unceasing atmospheric denuding 

 agencies which have operated since the last main elevation of the 

 Dividing Range in early Mesozoic times. 



Then earlier than this, in the Carboniferous period, there was a 

 stretch of ocean where now our picturesque Blue Mountain stand, 

 which extended from the Shoalhaven ranges on the south, to 

 beyond the point where the tunnel of the Great Northern Rail- 

 way pierces the Dividing Range near Murrurundi. And the 

 mountains of New England are not much oldei', for we find that 

 the granites composing them have upheaved and tilted the lower 

 Carboniferous or Devonian strata surrounding them. 



We have no evidence to show that the higher points of our 

 Dividing Range, or those over 4000 feet above the sea level, have 

 again been submerged since the general upheaval, after the deposition 

 of the Hawkesbury formation of our Blue Mountains. There is 

 little doubt but that the first surface undulations which appealed 

 as the land rose from the sea were the guiding features for the 

 development of our ranges and deeply eroded valleys. The 



