BY H. C. RICHARDS. 197 



granitic rock and the world's average basaltic rock. (See 

 Table X.) Whether this has any significance or not it is 

 difficult to say, but it is certainly a matter of interest in 

 view of the fact that there are many ardent advocates of 

 the view that there are two primary magmas, an acid and 

 a basic one. In any case, a commingling of these two 

 magmas could only be regarded as furnishing the magmatic 

 material which became differentiated somewhat on the lines 

 outlined above. 



IX. SUMMARY. 



The area dealt with is one of 4,000 square miles, and 

 is in the extreme south-eastern corner of Queensland. 



The physical features have several marked charac- 

 teristics, and a close relationship between them and the 

 volcanic rocks exists. 



Important earth movements of a vertical kind only 

 have taken place since the Palaeozoic era. 



Volcanic rocks occur in great abundance, and the dis- 

 tribution of these rocks and their relationship to the 

 sedimentary and metamorphic rocks of the area have been 

 described and illustrated by means of a sketch-map and 

 sketch-sections. 



The maximum thickness of the volcanic products is 

 approximately 3,000 feet, and three well-marked strati- 

 graphic divisions of these have been definitely established. 



A close correlation between these volcanic rocks and 

 those of Cainozoic age in New South Wales and Victoria 

 has been shown. 



The upper division has a maximum thickness of 2,000 

 feet, which is common throughout a large portion of the 

 area, and which is made up of a large number of flows of 

 basalt, andesitic basalt, and andesite ; in some places pyro- 

 clastic accumulations occur. 



The middle division has a maximum thickness of 1,000 

 feet, and is made up of acid and sub-acid lava flows, plugs, 

 and in the south of a very extensive development of acid 

 pyroclastic material. 



