1872.] 



DITNTREE GEOLOGY OP aUEENSLAND, 



281 



Belemnites are strewn over the surface of the two ridges which 

 front the Cattle-station huts, but they are rarely found in the soft 

 shales 'which crop out from under an escarpment of "Desert Sand- 

 stone." 



The lithological character of these Cretaceous strata is such that 

 decomposition is rapid ; and cliff-sections are accordingly very rare, 

 the resulting physical aspect being that of vast plains, which form 

 the principal feature of Queensland scenery west of the main 

 dividing range ; but that the " Desert Sandstone " has extended 

 over all this country is evidenced by its existence either in the form 

 of outliers, or as a marked feature in situ on all main watersheds, 

 or by its pebbles of quartz and conglomerate, which are strewn 

 everywhere over the surface of the plains. The appearance of these 

 vast plains is shown in Pig. 8. 



The height of the watershed between the Thompson and Flinders 

 rivers is locally not more than 1400 feet above sea-level ; and as 



Fig. 8. — Physical Character of Cretaceous Strata, Flinders River, 

 Western Queensland. 



the former river has to travel as many miles before reaching the 

 sea, it is easy to understand why, in a country subject to heavy 

 tropical rains at one period of the year followed by a long dry 

 season, the river-channels are ill-defined, and vast tracts of country 

 covered by alluvial deposits. 



Down the Thompson and its tributaries these Mesozoic rocks are 

 known to extend, though much obscured by flood-drifts. The first 

 to draw attention to the fact was the Rev. W. B. Clarke, F.G.S., of 

 Sydney, who in the year 1867 received a suite of fossils from "VVol- 

 lurabilla Creek and the surrounding district, which he described in 



VOL. XXVIII. PAKT I. X 



