192 NOTES ON SOME GEOLOGICAL OBSERVATIONS, WEST COAST. 



quite capable of producing deposits of iron ore on the surface, 

 without there being any lodes required to account for their 

 formation. The ferruginous waters resulting from the 

 solution by carbonic acid of the iron of the rock on coming 

 to the surface are sure to deposit their iron as hydrated 

 oxide. A gossan formed in this way would be rather a bog 

 iron ore than a true lode gossan ; and many of the so-called 

 gossan outcrops on these silver-fields appear to me rather to 

 be beds of surface bog iron ore than true gossans. The 

 highly ferriferous serpentine rock has yielded much surface 

 bog iron ore in the same way, as may be seen on the road 

 from Trial Harbour to Mount Zeehan, almost immediately 

 after coming upon the serpentine. Too much importance 

 should therefore not be attached to gossan outcrops as 

 indications of mineral lodes. In this connection, too, I may 

 point out that it frequently happens that quite a small lode 

 nas a large "iron hat" owing to the ferruginous waters 

 issuing from it spreading over the surface of the ground. A 

 big " gossan blow " need not cover an equally big lode by any 

 means. In making these remarks I am not forgetting that 

 in Smith and Bell's section the gossan is in at least one place 

 clearly derived from the oxidation of a lode containing much 

 carbonate of iron. 



At Mount Dundas I did not notice any dioritic dykes, but 

 in the southern of Webster and Bennett's sections I found a 

 volcanic breccia of fragments of felspathic rock, similar to 

 the diorite. In all probability the igneous rocks will prove 

 to be common at Mount Dundas as well as at Mount Zeehan. 

 Their intrusion may have been the cause of the fractures in 

 which the lodes formed, and the solf ataric action accompanying 

 volcanic activity may have had much to do with the filling 

 of the fissures with their mineral contents. 



Between the "Whyte River and the Magnet Range there is a 

 large quantity of a rather fine-grained greenstone, which does 

 not closely resemble the serpentinous greenstone on the west 

 side of the Heazlewood field. In the cuttings for the road on 

 the long grade down from the top of the Magnet Range, this 

 rock is seen penetrating the slates and altering them, to hard 

 brown porcelain-jaspers. I am not at all clear as to whether 

 this is not yet another separate igneous intrusion. Analysis 

 and microscopic comparison with the other greenstones are 

 required to solve this problem, together with field observations 

 to the northward of the Whyte River silver-field, where the 

 Magnet Range greenstone seems likely to join with the 

 serpentine rocks. 



The basalt dykes and flows met with on the West Coast all 

 probably belong to the series of tertiary basalts found 

 abundantly along the North and North- West Coasts. About 

 10 miles and 8 miles south of Corinna I noticed two dykes or 



