BY A. N. LEWIS. M.C.. LL.B. 21 



and east by Permo-Carboniferous mudstones, to the west by 

 basal conglomerates of that system, and to the south they 

 are separated from the similar rocks of the Jubilee Ranges 

 by ridges of diabase. They appear to underlie the diabase 

 throughout the whole area and to be exposed when the 

 valleys have been eroded sufficiently deeply. The writer is 

 inclined to think that the area shown on Mr. Reid's map as 

 occupied by Permo-Carboniferous sediments is too extensive, 

 and that most of this country, except on the south-eastern 

 slopes of Mt. Mueller, consists of older quartzites. The 

 quartzites outcropping on the road to Mayne's Farm at the 

 base of Pine Hill is streaked with veins of quartz containing 

 quantities of iron pyrites. 



As indicated on Mr. Reid's map and on the sketch 

 accompanying this paper, two beds of limestone occur in the 

 valleys of the two northern branches of the Weld. This is 

 a hard white rock of the Gordon River Limestone series 

 (Twelvetrees, 1908). The writer can only confirm Mr. 

 Twelvetrees' remarks on the occurrence, which should be 

 referred to for a more detailed account of the country 

 traversed by the South Gordon track. 



(c) Permo-Carboniferous and Trias-Jura. 



Sediments of this age appear along the eastern side of 

 the area, the line of the valley of the Weld being approxi- 

 mately the present junction line between the newer and older 

 rocks in this part of Tasmania. The base of the Permo- 

 Carboniferous system consists of glacial conglomerates. 

 Two small but excellent examples of this formation, which 

 is so well developed at Wynyard, are to be seen in the area. 



One of these occurrences, extends from about a mile 

 west of Fourteen Mile Creek on the Tyenna-Port Davey 

 track, to the top of the Russell Falls River-Styx divide on 

 the south-eastern spur of Mt. Mueller. The beds are exposed 

 for three miles or so along the track. They consist of the 

 typically grey, clayey matrix, showing little signs of strati- 

 fication, and only just resistant enough to require the use of 

 a hammer, studded with pebbles and boulders of all sizes, 

 but chiefly smaller than a cricket ball, consisting of grey 

 quartzite, quartz, slate, and mica-schist. There is a strange 

 absence of red granite. Mr. Twelvetrees mentioned the 

 existence of Pormo-Carboniferous conglomerate here, but 

 apparently did not recognise its glacial origin. The Pre- 

 Cambrian mica-schist boulders reported by him from Four- 

 teen Mile Creek were probably derived from this tillite. Mr. 



