552 president's address. 



serpentine, with massive deposits of haematite and magnetite. In 

 the Meredith Range limestone is mentioned^-' as forming the 

 uppermost member of the Archcean Series. 



The eruptive rocks are not necessarily contemporaneous with the 

 metamorphosed sediments, and the iron ore deposits occur as true 

 mineral lodes near Yorktown,t and rest on a floor of serpentine. 

 The presence of from three to five per cent, of chromium sescjuioxide 

 in the Yorktown iron ore shows that the ore has probably been 

 derived from the serpentine. The iron ore deposits are probably, 

 therefore, of later origin than the Archaean rocks, and not con- 

 temporaneous like those of the Archaean region of North 

 America. 



The limestone, however, if its age be truly Archaean, of course 

 implies the probable contemporaneity of animal or plant life as 

 does the dolomite and limestone of the Macdonnell Ranges of 

 South Australia. 



Their thickness has not yet been calculated. Their general 

 strike is N. 25- W., and they are foliated, the folia dipping gener- 

 ally at steep angles. As the Cambrian rocks of the Mersey 

 District are not foliated but simply steeply inclined and folded, 

 it is probable that the Tasmanian Archseans were disturbed and 

 thrown into folds before the Upper Cambrian strata were laid 

 down. 



(6) In New Zealand the crystalline and foliated schists of the 

 Southern Island may be in part Archaean. In the Otago District 

 they cover an area of 8000 square miles, and are considered by 

 Sir James HectorJ to be chiefly altered Silurian or even Car- 

 boniferous rocks. 



Sir James Hector states§ that in the Nelson and Westland 

 Districts granites occur of Pre-Silurian Age. They may, of 



* Loc. cit. p. 20. 



t f. Gould, quoted by Johnston, loc. cit. p. 27 onwards. 



X Indian and Colonial Exhibition, London, 1886, New Zealand Court. 



Detailed Catalogue and Guide to the Geological Exhibits, by Sir James 



Hector, F.R.S. By authority. Wellington, 1886. 



§ Loc. cit. p. 85. 



