250 PROCEEDINGS OF SECTIOIQ^ C. 



and Eelationships of Alkaline Rocks," in the Proceedings of the 

 Linnean Society of New South Wales, 1908, Vol. XXXIII., Part 3. 

 Keferences to all the author's other papers on alkaline rocks, and to 

 the work of other investigators on the same topic may be found in 

 the same paper. 



It is the author's object to outline in the present paper the main 

 features of the alkaline areas of Southern Queensland. Other alkaline 

 areas do exist in the State, such as the alkaline trachytes of the 

 Yeppoon Range, in Central Queensland, and similar masses in the 

 Springsux'e and Clermont districts, but they have never been 

 thoroughly examined. 



The best known group of such rocks is that of the Glass House 

 Mountains, which is situated on the North Coast Railway line, and 

 is a popular tourist resort. Yet so little interest was taken in the 

 geology of the disti-ict that, until a few years ago, those wonderful 

 trachyte pinnacles v/ere taken for masses of metamoi-phic sandstone. 

 To Mr. H. G. Stokes belongs the credit of discovering that they con- 

 sisted of trachyte. 



Our vice-president, Mi'. R. A. Wearne, B.A., of Ipswich, has col- 

 lected extensively in the Mount Flinders area and in the Little Liver- 

 pool Range, and to him belongs the credit of having first established 

 that alkaline trachytes are abundantly represented in these areas. 



2. Geological Structure of the Coastal Portions of SoutheriN 

 Queensland.— It will be seen on reference to the geological map of 

 Queensland that, from the Brisbane River northwards to the mouth 

 of the Mary River, the coast is bordered by Trias-Jura coal measures. 

 I have in one of my papers* shown that the Ipswich and Burrum 

 beds are not separated by a strip of Gympie formation at Point Ark- 

 wright, as shown on the old geological map of Queensland, but they 

 are continuous. There is probably no unconformity between them. 

 The Mesozoic beds, between Brisbane and Gyrtipie, form a compara- 

 tively narrow coastal plain, west of which the country rises sharply 

 and Palaeozoic rocks displace the Trias-Jura. The line along which 

 this change sets in is also characterised by the appearance of volcanic 

 rocks, which are particularly abundant along and a couple of miles on 

 either side of this line. Thus, close to the junction of the Palaeozoic 

 and Mesozoic, we have the basalts of Mount Mee, the trachytes of the 

 Glass Houses, and the andesites and rhyolites of the Tuchekoi Range; 

 whereas the Blackall Range basalts partly cover the line. The 

 coastal plain is partly covered Avith Tertiary alluvium, and shows indi- 

 cations in many places, especially in the Maroochy district, of recent 

 emergence. Behind the plain lies a low tableland, the coastal range 

 having but a slight fall to the west. This tableland has the character 

 of a Tertiaiy peneplain. 



A similar stmcture is obsei-ved in the Fassifem district south of 

 Ipswich, where, behind the plain of Walloon coal measures, the 

 trachj'te peaks of Mount Mitchell, Spicer's Peak, Mount Huntley, and 

 Mount Roberts, &c., form the culminating points of the Little Liver- 

 pool Range, which has only a slight fall to the Darling Downs on the 

 west. The Downs constitute a plain or peneplain (probably a Tertiary 

 peneplain) covered with basalts of late Tertiary age. 



* Geology of the Volcanic Area of the East Moreton and Wide Bay districts. 

 Proc. Linn. Soc. of N.S.W. 



