26 



w. a. DUN. 



the Blythesdale Braystone is actually a calcareous sand- 

 stone, the surface porosity of which is due to the leaching 

 action of terrestrial waters and is only superficial, the 

 dense rock being met with at depths of from twenty to 

 fifty feet. 



Towards the close of the Cretaceous era, there was, as 

 happened in Europe and in America, and in fact as in all 

 cases of inlocked estuarine or marine areas of oceanic and 

 drainage deposition associated with a stable isostatic con- 

 dition of the general region, a gradual shoaling, a recession 

 of the sea, and a reduction in the area of denudation r 

 leading to the condition of reduction of stream to base 

 level. 



The concluding stages of Cretaceous sedimentation at 

 any rate in Northern Queensland are represented by a 

 series of coarse sandstones, grits and fine conglomerates. 

 These are frequently red-coloured and show examples of 

 cross bedding. This appears to be clear evidence that they 

 represent the last stages of the elevation of this area of 

 land, the rapid shoaling of the sea and the assumption of 

 estuarine conditions and its associated faunal changes and 

 gradual extinction of the marine fauna. 



It may be seen by a study of the fossils, that the vari- 

 ation in fauna between the lower and the upper members 

 of this unbroken series of sediments, can be accounted for 

 adequately by the alteration of shore conditions, and by 

 the probable alteration during the later period of the 

 composition of the water. The term "Desert Sandstone" 

 has been much misapplied. As used by Daintree in the 

 first case, it was a correct phrase as expressing the upper 

 members of a great system, but when we find that Tate in 

 the Journal of the Horn Expedition, has described sand- 

 stones and quartzites containing Dicotyledonous leaves of 

 Tertiary Age, and Eocene and Miocene, as that of Desert 



