l^O THE GEOLOGY OF TASMANIA— THE PRE-CAMBRIAN. 



which He to the north of the Raglan Range. On the 

 north-east it extends to the edge of the Central Plateau, 

 where the upper Mesozoic diabase covers it. 



The Raglan Range, the Frenchman's Cap, and De- 

 ception Range form the observed western borders of 

 this area. On the eastward the lower slopes of Mount 

 Gell, Mount Arrowsmith, and the western slopes of the 

 Loddon Range form the limits of these schists. A con- 

 siderable area of Cambrian rocks has been seen to over- 

 lie the Pre-Cambrian to the east of the Frenchman's 

 Cap. And Ordovician limestone has been located in the 

 beds of the Denison and Jane Rivers. (It has been 

 found impossible to represent the Jane River limestone 

 on the map, for the reasons that the outcrop is abso- 

 lutely restricted to the river bed, and the scale of the 

 map will not admit of the representation of such a 

 narrow band.) 



The eastern boundar}' of the Pre-Cambrian Ues to 

 the west of the Denison Range, and crosses the Gordon 

 River near the junction of the latter with the Wedge 

 River. Thence it has been observed to run southwards 

 a little to the east of Lake Pedder. Beyond this point 

 it has not been followed, but it is thought to continue 

 to the south coast near the New River. 



This southern extension of the Pre-Cambrian em- 

 braces the Frankland Range, and probably the country 

 between that range and Port Davey. 



All varieties of quartzites, quartzite-schists, mica- 

 ceous, argillaceous, and graphitic schists are found 

 within the limits of this area. The probable existence 

 of an upper horizon of quartzite-schist has been indi- 

 cated above. 



To the west of the Denison Range the strike is 

 usually north-easterly. South of the Gordon River the 

 strike varies between N. 5deg. and N. 3odeg. W. 



IX. The most southerly development is that which 

 extends from a point to the westward of New River 

 along the south-western coast beyond Port Davey. This 

 area is pierced bv a small intrusion of granite at Cox's 

 Bight (I). 



(i) See W. H. Twelvetrees' " Report on Cox's Bight Tia 

 Field,"' 1906. 



