142 THE GEOLOGICAL AGE OF VOLCANIC ACTIVITY 



Mr. S. B. J. Skertchly, in a report on the geology of 

 the country round Stanthorpe and Warwick, refers to the 

 basalt of the Toowoomba Range as Tertiary, but d(o,es not 

 record the sections which lead him to that conclusion. 



Dr. H. J. Jensen has made several important contribu- 

 tions to the study of South- East Queensland igneous rocks, 

 chiefly in papers read before the Linnean Society of X.S.W. 

 The rocks described are in the East Moreton as well as in 

 the Fassifern districts, and he refers all of the volcanic 

 rocks he found on Trias-Jura areas to a post-Trias-Jura age. 

 He records, in the Fassifern district, trachyte dykes in the 

 Trias- Jura sandstone, a basalt injected in and overlying 

 the trachyte, but gives no actual section proving, in our 

 present ignorance as to the horizon occupied by the sand- 

 stojnes intruded, that the volcanic rocks are post Trias-Jura. 



Mr. E. C. Andrews, of the New South Wales Geological 

 Survey, in working near the Queensland border, referred 

 the trachytes and basalts of the Macpherson Range to the 

 Trias-Jura age, but subsequent work has, the writer under- 

 stands, led him to regard them as of Tertiary age, corres- 

 ponding presumably with the undoubted Tertiary basalts 

 of New England, described by Prof. David, as well as by 

 himself. 



The present \vriter, in examining the coal measures 

 south of Brisbane, came to the conclusion that the volcanic 

 rocks met with — almost entirely of the basaltic type — 

 belong to two ages, Trias- Jura, and late or post- tertiary. 

 Several sections were observed, including Mr. Rand's 

 Woodhill trachyte, of interbedded volcanic rocks amongst 

 the upper or Walloon coal measures, in the neighbourhood 

 of Beaudesert. These occurrences, however, are possibly 

 merely sills or dykes parallel to the bedding, though an 

 examination of them does not give one that impression. 

 In a flying visit to the coal seams outcropping in the Upper 

 Logan district, a site was pointed out by Mr. J. Buchanan, 

 where an outcrop of carbonaceous shale or weathered coal 

 had been covered by a recent slip in the bank of Christmas 

 Oreek. Mr. Buchanan remarked on the outcrop having 

 been perpendicular, and the Avriter observed that sandstone 

 in juxtaposition with the fallen ground was also perpen- 

 dicular, and that this sandstone contained rounded pebbles 

 of basalt similar microscopically to the andestic basalt 



