West Tamar District, Tasmania. 161 



out like a lava sheet, at what time it is impossible to say. 

 It is not interbedded here, but is, I believe, in the Fingal 

 district ; and, if so, it is of carboniferous age. Its only 

 covering in this district now is a tertiary drift, although an 

 older one may have been denuded away. It occupies a 

 very small area, but is largely represented to the east of the 

 river. 



An older pliocene tertiary drift, derived from the denuda- 

 tion of the silurian rocks and their contained reefs, covers 

 the entire area of the higher portions of the low country 

 between the two arms, almost completely obscuring the 

 underlying rocks. It also caps the silurian and serpentine 

 hills up to elevations of nearly 300 feet above sea level, 

 between the Cabbage-tree Range and Anderson's Rivulet. It 

 is very widely spread ; but I have little doubt but that 

 " leads" would be found, if looked for, in some portions of it. 

 The Italian's and Scotchman's Company tunnelled into it on 

 a head of Brandy Creek, west of the Cabbage-tree Range, 

 and struck a " lead," with good prospects, but were driven 

 out by water. " Made hills" occur along the valleys of the 

 Yorktown and other creeks running up into the silurian and 

 metam orphic ranges. 



The ironstone hills, Mounts Vulcan and Scott, and Barnes' 

 Hill, as well as other small outliers, would appear to belong 

 to this period. Of the latter, the Tamar Company's iron- 

 stone, being off the serpentine, and free from chromic iron, 

 yielded very fine pig iron, but is now worked out. Mounts 

 Vulcan and Scott, the property of the British and Tas- 

 manian Charcoal Iron Company, are situated about five miles 

 southerly from their works at Port Lempriere, with which 

 they are connected by a railway. Mount Vulcan is 278 feet 

 above sea level, and consists of more or less decomposed 

 serpentine. The iron ore (limonite) is evidently of tertiary 

 origin, filling a pocket or depression on the north sides of 

 the hills similarly to many European deposits. The top of 

 the hills is covered with an agglomerate of ironstone pebbles, 

 which are polar-magnetic, and the flanks with flat, striated 

 pieces, from a quarter to half an inch or more thick, of magnetite, 

 derived from veins already mentioned. The striations or 

 grooves of the magnetite correspond with and run in the 

 same direction as the asbestus fibres enclosing it. In some 

 larger blocks of magnetite, occurring in the limonite, the 

 grooves, instead of being straight, are much twisted, and 

 resemble the foliations of metamorphic schists. Some of the 



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