PRESIDENTIAL ADDRESS. 



25 



which more siliceous beds occur low down in the series. 

 These are simply local occurrences, and are due to proximity 

 to shore lines bounded by the friable Ipswich and Bundamba 

 Sandstones. This constitutes the at one time famous 

 Blythesdale Braystone, considered to be the intake region 

 of our Oretaceous Artesian water supply, though it has 

 been shown that, at any rate in the more southern districts, 



140 Longitude iso East of na 



Map of Australia showing extent of Cretaceous Mediterranean Sea. 



