AUSTRALIAN MINING-FIELDS 



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the finest serial yet published on Australasian geology. But 

 the work that has since been carried on has exposed the 

 structure of the lode to a greater depth and length than in 1894, 1 

 and we know more about the Archean rocks of Australia than 

 we did then. The later workings show in places the arch-like 

 fold of the reef, which was especially well exhibited at the time 

 of my visit in the South Broken Hill Mine. But the general 

 evidence now available seems to me to show that the lode is not 

 a true saddle reef. In the first place, the rocks are not, in my 



Fig. 6.— A Saddle Branch or False Saddle Reef at the North Lyell Mine. 

 o. Ore body. c. Conglomerate and quartzite. s. Schist. 



opinion, altered Palaeozoic sediments, but foliated Archean igneous 

 rocks ; and there is no reason to expect the same persistence in 

 the crumplings of gneisses, as in the folding of a thick mass of 

 sediments. It seems to me inadvisable to extend such terms as 

 anticlinals, from bedding planes in sediments, to the less regular 

 foliation planes, developed by flow or metamorphism, in 

 igneous rocks. 



Further, the structure of the lode seems to me essentially 

 different from that of a true saddle reef; the sections on fig. 5 



1 An excellent account of the field up to 1900 is given by E. F. Pittman, The 

 Mineral Resources of New South Wales, 1901, pp. 92-107. 



