Geology of Hobart Town. 135 



Above the claystone is a great thickness of sandstone. 

 This stratum is singularly bare of organisms. But as sand- 

 stones generally contain but few fossils, the barrenness, in 

 this instance, is no proof that the seas were untenanted 

 with life. 



Interstratified with the upper portion of the sandstone 

 beds, are layers of shale, bearing impressions of fern leaves 

 and calamites, together with one or two thin layers of coal, 

 changed for the most part into anthracite. 



The absence of Sigilaria, Stigmaria, Lepedodendra, and 

 other plants characteristic of the English coal measures, 

 would seem to suggest that the coal of Tasmania, like that 

 of Victoria, is not of the true carboniferous period. 



What may, in some measure, go to confirm the opinion so 

 hazarded, is the discovery in the sandstone of a bone, said by 

 Professor Owen to be that of a Labyrintkodon, a batrachian 

 generally associated with rocks of the Triassic age. 



A Hobart Town geologist (Mr. Morton Allport), who first 

 directed my attention to this interesting fossil, supposes the 

 rock from which it was taken to be situate above the coal 

 beds of the district. 



It is with extreme diffidence that I venture to express an 

 opinion, but I had thought, and still think, from an exami- 

 nation of the locality, that the bed, in which the fossil was 

 discovered, lies far below the carbonaceous strata, and that 

 the carbonaceous strata in that particular spot have been 

 swept away by denudation. This would render the fossil of 

 great use in determining the geological position of the Tas- 

 manian coal beds, and show that they were deposited con- 

 temporaneously with the reptilian forms characteristic of 

 the secondary period. 



It may be asked, as the limestone is of Palaeozoic and the 

 coal of Mesozoic age, whether the surface remained unsub- 

 merged daring the intervening period, or whether there has 

 been a subsequent removal of rocks once deposited ? 



Perhaps it may appear that neither of these alternatives 

 is absolutely required. The Permian group may, after all, 

 be represented by a portion of the strata intervening between 

 the limestone and the coal, although, through the absence of 

 fossils, no evidence of the fact is anywhere apparent. The 

 magnesian limestone characteristic of the Permian age may 

 have been so far local as to be excluded* altogether from 

 Tasmanian waters. Probably the beds, during the course of 

 formation, resembled, not a little, the accumulations of sand 



