VOLCANIC ACTION IN EASTERN AUSTRALIA. 399 



At Mount Lambie Rhyncnonella pleurodon is abundantly asso- 

 ciated with Spirifera disjtincta, and may therefore be of Upper 

 Devonian age, at the Clyde Mountain, near Braidwood. 



Evidence has not yet been obtained as to Avhether the quartz- 

 felsite of Hack Creek, near Major's (heek, is a lava or a plutonic 

 laccolite. Its age is clearly older than either Upper Devonian or 

 Lower Carboniferous. 



The possibility suggests itself of this quartz-felsite being honio- 

 taxial with the Snowy River porphyries, which are probably of 

 Lower Devonian age, according to A. W. Howitt and R. A. F. 

 Murray. The gold-bearing granite of Braidwood and Major's 

 Creek is of later origin than the quartz-felsite and also than the 

 Upper Devonian (?) sediments, which latter have been much 

 altered and considerably disturbed by the granite. The granite is 

 almost certainly of contemporaneous origin with the gold-bearing 

 hornblendic granites of Hartley and Bathurst, which are later than 

 the Upper Devonian and older than the Permo-Carboniferous (as 

 that term is used in New South Wales), that is, older than the 

 strata containing 6rVoASo/?/e?-?'>-bearing coal measures associated 

 with a marine fauna, which has affinities partly with the Permian 

 and partly with the Carboniferous of Europe. [The Queensland 

 geologists include under the term Permo-Carboniferous the Lejri- 

 dodrendon australe beds occurring in the Star and Gympie Forma- 

 tions in that colony. Beds containing similar fossils in IS^ew South 

 Wales are referred either to the Carboniferous or to the top of 

 the Upper Devonian rocks.] 



As regards the intrusion of the granite near Braidwood it is 

 interesting to note that it has forced a passage for itself through 

 the outer portion of the earth's crust almost entirely at the expense 

 of some sediments Ij'ing to the east of the quartz-felsite, and 

 apparently vmconformable to the overlying rocks of Upper 

 Devonian age, whereas it has disturbed the quartz-felsite on its 

 Avestern margin near Back Creek to only a very limited extent. 

 Probably the quartz-felsite resisted the lateral thrust of the granite 

 more successfully than did the sediments. 



The purple shales associated with the Lepidodendron beds at 

 Back Creek show that lithologically as wtII as palaeoutologically 

 they are related to the Upper Devonian at Mount Lambie, for at 

 the latter locality Mr. Pittman and I lately observed that purple 

 shales several hundred feet thick are interstratified with the 

 Spirifera disjuncta beds fv. Plate XV., section 2). My field 

 experience in New South Wales has led me to the conclusion 

 that most of such purple shales result from the alteration of fine 

 tuffs, and their presence is therefore an indication of probable 

 contemporaneous volcanic action. Near the Avon River in Victoria 

 the purple shales associated Avith the Lepidodendron beds are 

 evidently related to volcanic rocks, as they are there intimately 



