238. proceedings of section c. 



2, — Western Australia. 



Mr. A. Gibb Maitland reports : — There have, I regret to say, been 

 no new discoveries to report in regard to the structural features of 

 Western Australia since the last meeting of the Association, 



I enclose an advance copy of a map showing the Darling 

 Peneplain and Fault Scarp, which accompanies a physiographical paper 

 by Mr. Jutson, in Bulletin No. 48, now in the press. 



3. — Northern Territory. 



Prof. W. G. Woolnough reports : — I have the honour to bring before 

 your notice a suggestion with respect to the geological structure of 

 Australia, the result of my recent trips to the Northern Territory and 

 Western Australia. 



The marked contrast between the geological features of Eastern 

 and Western Australia is most pronounced, and extends from Cambrian 

 time at least to Tertiary. 



In Eastern Australia Palaeozoic and even Mesozoic rocks are strongly 

 affected by earth movement, and by granitic movement and by granitic 

 intrusions. There appears to be a progressive difference in point of 

 time for these movements and injections as we pass from south to north. 

 In southern New South Wales Ordovician rocks are strongly folded and 

 contorted, while Silurian rocks are affected by only very gentle and 

 uniform dips. In the initial portions of the New South Wales coastal 

 area Permo-Carboniferous formations are strongly folded, and are 

 intruded by granites. In southern Queensland the Trias-Jura coal 

 measures are considerably disturbed, while, at Port Moresby, in 

 Papua, even Tertiary beds are intensely contorted and overfolded. 



In Western and Northern Australia the condition of affairs is 

 quite different. Immense developments of Pre-Cambrian rocks occur, 

 giving clear evidence of subdivision into quite a number of distinct 

 epochs, but all these Pre-Camhrian rocks alike are intensely folded and 

 moderately metamorphosed. Cambrian sediments are wide-spread also, 

 the great Cambrian province extending from Kimberley, in Western 

 Australia, across the whole of the Northern Territory, and well into 

 Queensland, being perhaps the most extensive area of such rocks in 

 the world. The Nullagine series of Western Australia, which is almost 

 certainly Cambrian, is only gently folded. The Cambrian rocks of the 

 Northern Territory, while they are considerably disturbed in places, 

 are for the most part horizontal or gently undulating as regards dip, 

 and the degree of metamorphism is comparatively insignificent. In 

 neither Western Australia nor Northern Territory, nor, so far as I am 

 aware, in western and northern South Australia is there a single instance 

 of granitic intrusions into rocks more recent than Pre-Cambrian. This 

 is in marked oonfarast to the Pre-Cambrian formations, which are 



