280 C. A. SUSSMILCH AND T. W. E. DAVID. 



conglomerates in the eastern part of the same country, 

 the latter of which occurs at the base of the Pennsylvanian 

 System, and the former possibly on a similar or higher 

 horizon. 



The deposition of the Wallarobba Beds was followed by 

 a period of intense volcanic activity, during which the 

 Martin's Creek series of lavas and tuffs was erupted. This 

 series of volcanic rocks has been traced by the writer from 

 the coast at Port Stephens westwards to Lamb's Valley; 

 while W. R. Browne has noted a similar series at Hudson's 

 Peak, and Dr. A. B. Walkom 1 has noted a similar volcanic 

 series of rocks further to the north-west at Mount Tangorin; 

 and Prof. W. N. Benson 2 has recorded similar volcanic rocks 

 in the Nandewar Ranges. This volcanic series thus extends 

 along a distance of not less than 250 miles. Throughout 

 this distance, the lava flows display a remarkable uniformity 

 of petrological character. During the epoch of the succeed- 

 ing Mount Johnstone beds, volcanic activity still continued 

 but was somewhat less intense, and is represented mainly 

 by tuffs. Undoubtedly, lakes existed at this time, and in 

 these were deposited the sediments in which the Rhacop- 

 teris flora was preserved. That the neighbouring land was 

 still high is indicated by the frequent beds of conglomerate 

 which occur interstratifled in this series. That these 

 highlands possibly supported glaciers is indicated by the 

 close lithological resemblance of some of the mudstones 

 deposited at this time with the undoubted glacial muds 

 deposited in the succeeding glacial beds. 



The Rhacopteris flora preserved in the Kuttung strata 

 is an entirely new flora as compared with that of the 



1 "Geology of the Permo-Carboniferous System in the Glendon Brook 

 District, near Singleton," by A. B. Walkom, Proc. Linn. Soc. N.S. Wales, 

 Vol. xxxviii, Part \, 1913. 



a "Geology of the Great Serpentine Belt," by W. N. Benson, Proc. Linn. 

 Soc. N. S. Wales, Vol. xxxvm, Part 4, 1913. 



