770 E. C. ANDREWS 



in age, although there are certain indications of relative youth in 

 the gold deposits of the Northern Territory and South Australia. 

 Eastward, in the old trough lying within New South Wales and 

 Victoria, now filled with Cambro-Ordovician and infolded Silurian 

 sediments, occur the most important gold deposits of Australasia, 

 especially the famous saddle reefs of Bendigo, Ballarat, Canbelego, 

 and other localities. Immediately to the east and north lie the ore 

 deposits beyond the Hunter zone of weakness where Benson's line 

 of serpentine occurs with its gold deposits of Carboniferous age. 

 Beyond, but parallel, or subparallel, with these, are the great gold 

 fields of the closing Paleozoic period in New England and Eastern 

 Queensland, as, for example, at Hillgrove, Gympie, Mount Morgan, 

 and the Palmer. It might be mentioned that, although no gold 

 deposits appear to have been formed in Australia since that momen- 

 tous period, nevertheless the important gold deposits of the North 

 Island of New Zealand are of late Tertiary age. It might be men- 

 tioned here that the gold deposits of Southwestern New Zealand 

 appear to occur in Paleozoic rocks. 



Or it would have been interesting to enlarge upon the facts 

 connected with the copper deposits of Australia: how in the 

 west they are of pre-Cambrian age, according to Maitland and 

 his geological staff; how the nature of the deposits there suggests 

 deposition at a great depth below the old land surface; how the 

 copper deposits of great but of unknown age, in the Northern 

 Territory, South Australia, Western New South Wales, and Tas- 

 mania, as, for example, at Wallaroo, Moonta, Burra Burra, Cobar, 

 Nymagee, and Mount Lyell, do not appear to be dependent upon 

 ordinary igneous rock types, but, from an examination of the reports 

 of Ward, Jack, J. W. Gregory, and the writer, they appear to be the 

 equivalents themselves of igneous rocks because of their peculiar 

 mineral assemblages; how with these famous deposits might be 

 mentioned the great Broken Hill deposit of silver-lead and zinc 

 which is apparently a replacement of schists by garnet, rhodonite, 

 feldspar, and sulphides, owing to the action of vapors arising along a 

 shear zone; 1 how the arrangement en echelon of these metalliferous 

 areas and the individual ore lenses within such areas must be sig- 



1 E. C. Andrews, "Broken Hill Lode," Economic Geology, October, 1908, pp. 643-45. 



