BY H. C. RICHARDS. 127 



page 123), and there is no doubt that the "sandstone" in 

 juxtaposition to the fallen ground which contained pebbles 

 of andesitic basalt is in reality the acid pyroelastic 

 material which occurs developed to such an extent in that 

 area. There is absolutely no trace of included fragments 

 of volcanic rock in the mass of included shale, but the 

 volcanic fragmental rock which surrounds it is thickly 

 strewn with both rhyolitie and basaltic fragments, some of 

 which attain several inches in diameter. The so-called 

 ''similar sandstone" further down the creek is also the 

 acid pyroelastic material. I have communicated with Mr. 

 Marks who is now in Dublin, and he quite accepts my 

 interpretation, indicating also that he did not have a 

 proper opportunity of thoroughly investigating the section. 

 He writes : ' ' The fact that the upturned strata are only 

 part of a comparatively small mass enclosed in the tuff 

 is an unexpected explanation of the section which I could 

 only explain by contemporaneous action. It is veiy in- 

 teresting and of course accepted, and removes the only 

 definite evidence I saw of contemporaneous vuleanicity." 



The material called desert sandstone by the late Mr. 

 Rands," and which forms the sunnnit of the ranges between 

 Nixon's Creek and Back Creek, is also the acid pyroelastic 

 rock. 



It is somewhat remarkable that both Rands and Marks 

 should have regarded this material as sandstone, but the 

 author of this paper is quite convinced of the real nature 

 of the material as he has had repeated opportunities of 

 investigations in innumerable cliffs, distributed over a 

 large area, and has also investigated micro-sections {see 

 Plate XIII.. fig. 3) of the more compact material. 



It is thus clear that Mr. Rands' pre-Cretaeeous age for 

 the basalt underlying the acid agglomerate and acid tuff 

 at Nixon's Creek and Nerang Creek is not borne out on 

 the evidence. 



Mr. Rands described the Woodhill trachyte as a flow 

 interbedded with the Walloon measures, but the true rela- 

 tionship is masked by faulting, and one needs to assume 



'''Q'laiid Geol. Surv., Pub. 51 (1889). 



