554 president's address. 



In the Otago District the folia have an ahnost constant dij) to 

 the west at from 45^ to 80°. Northwards from the Otago District 

 to Tasman's Bay at the north end of the South Island, tiieir strike, 

 as far as can be judged from the Geological map, is approximately 

 parallel with the principal axis of the South Island, that is S.W. 

 and N.E. 



It may be^oncluded thr.t in the South Island of New Zealand 

 there is a thiclv series of crystalline rocks partly eruptive partly 

 metamorphic, which in places, as near Collingwood, are strongly 

 unconformable to the overlying Lower Silurian rocks, and such 

 portions of them, therefore, must be Pre-Silurian, and therefore 

 either Cambrian or Pre-Cambrian, probat>ly chiefly the latter in 

 view of their extreme regional metamorphism, as compared with 

 the comparatively slight alteration of the Lower Silurian (Ordo- 

 vician) rocks in their neighbourhood. There is no evidence to 

 show that any })ortion of New Zealand was a land area in Pre- 

 Cambrian time. 



Siunmary of Archcean Group. — The -total superficial area at 

 present known to be occupied- by Archaean rocks in Australia 

 perhaps does not exceed about 20,000 square miles (about yi^ of 

 its whole area). This estimate is only very approximate, and 

 subsequent explorations may necessitate its being considerably 

 increased. In New Zealand the crystalline schists have an area 

 of 8,000 square miles, but only a small portion of this, if any, 

 may prove to be Archaean. In Tasmania no data are available 

 for calculating even approximately the area of the Arch^an rocks. 

 In Victoria, New South Wales, Queensland and the Northern 

 Territory of South Australia no Archaean rocks have as yet been 

 proved to exist, though hereafter it is possible that some of the 

 crystalline schists known to be developed in those portions of 

 the Australian Continent may have to be referred to the Pre- 

 Cambrian Group. 



The Australasian Archssan rocks consist of gneiss, mica schist, 

 chlorite or talc schists, hornblende schists, quartzites, conglome- 

 rates, micaceous red mudstones, marble limestone, hrematite, 

 ilmenite, and graphite. 



