204 PR0CEEDINC4S OF SECTION C. 



Rolling Downs. On the other hand my own explorations have 

 satisfied me that Queensland fossils are not more liable to this 

 kind of accident than fossils from other countries, that the 

 mixing-u]o which has so annoyed palaeontologists has been per- 

 petrated by nature herself ; that in the Rolling Downs we have 

 a continuous series of beds of enormous thickness, in which, 

 however, from the scarcity of sections, it would be impossible to 

 map out ' horizons ' ; and that the fossils from the Rolling Downs 

 must be treated as a whole." 



Everywhere in the north the Rolling Downs formation lies 

 directly, and of course unconformably, on schists and slates, or 

 granites, the Ipswich formation being absent. 



The Desert Sandstone is a monument of the power of denuda- 

 tion. It has covered the whole of the area now occupied by the 

 outcrop of the Rolling Downs formation — in other words, the 

 larger (the western) half of Queensland, though now it only 

 occurs in isolated fragmentary tablelands. It ovei'lies the 

 Rolling Downs formation unconformably, but the junction is 

 not merely an unconformability. It is an overlap. The sandy 

 sediments have filled up the inequalities in the older rocks, the 

 lowest bed occupying the bottom of the hollows, the next joining 

 the older rocks at a higher level, and so on. Consequently the , 

 formation, which rests unconformably in the western interior on 

 the Rolling Downs beds, rests unconformably on the Ipswich 

 beds, and comes at higher levels to rest unconformably on the 

 Palseozoic rocks, as the axis of the lofty coast range, which 

 formed the shores of the Desert Sandstone sea, is approached. 



The Desert Sandstone varies greatly in composition, texture 

 and appearance from top to bottom, but its individual beds 

 preserve their chai-acters over large are.ds. The lowest beds are 

 generally of felspathic material, without aqueous arrangement, 

 and are suggestive of wind-sifting only — volcanic dust in fact, 

 altered more or less by subsequent infiltration or segregation of 

 iron oxide or other cementing material. Other beds are of white 

 siliceous sand, and these have often a vitrified appearance, due 

 I believe to partial solution of the silica from the upward passage 

 of hot water. Other beds are of siliceous sand reddened with 

 iron peroxide. Other beds are coarse conglomerates. False 

 bedding is common in nearly all the siliceous strata. A few 

 beds of clay shales occur, and even some seams of coal. Nodules 

 of ii'onstone and silica occur in places, and these often contain 

 precious opals and other gems. 



The Desert Sandstone has till recently afforded very few fossils, 

 except silicified wood, generally structureless and without value 

 for palfBontological purposes. Daintree believed it to be Tertiary. 

 Mr. Norman Taylor obtained from it, at Battle Camp, near 

 Cooktown, two fossils, pronounced by 31 r. Robt. Etheridge, 

 F.R.S., to be Ostrea and Hinnites. Nothing of great importance, 



