183 



The geology of these islands is exceedingly meagre, but not uninteresting. 

 The rocks of which they are formed, judging from the specimens submitted, 

 thirty in number, being as follows : — 



1 . Dolerites, clay stones and basaltic porphyries. 



2. Chert and pitch opal. 



3. Tertiary sandstone and conglomerate with streaks of coal. 



4. Bituminous peat, like that which is found on the Chatham Islands. 



5. Fine-grained granite. 



6. Granite porphyry, syenite and hornblende rock. 



It thus appears to be a granite island, with patches of tertiary strata 

 resting in hollows on its surface-, and the whole overlaid, moi-e or less, by 

 volcanic rocks of post-miocene age. 



6. — Chatham Islands. 



The geology of this group has been made known to us by Dr. Haast's 

 notes on the collections of Mr. Henry H. Travers,* but since then two 

 important series of specimens of rocks and fossils, from the Chatham 

 Islands, have been deposited in the Museum, accompanied by copious notes. 

 The first consists of 200 specimens, forwarded in February, 1868, by Mr. Charles 

 Traill ; and the second, comprising 102 specimens, was received from Mr. 

 Percy Smith, in March, 1869. 



Notwithstanding the completeness of these collections, there is little to be 

 added, from their study, to the information we already possessed. 



The tertiary series, as in New Zealand, appears, however, to belong to 

 two distinct epochs, the upper of which is alone associated with igneous rocks, 

 chiefly dolerites. There also appear to be two distinct carbonaceous formations, 

 the older occurring in Pitt's Island, representing the brown coal series of New 

 Zealand, and a newer formation which may be considered as a modified peat, 

 which is quite superficial in the district south of the salt-water lagoon. In 

 this formation are large masses converted into a highly bituminous mineral, 

 probably by the action of the fires described by Mr. Travers,t "which might prove 

 of considerable value, either as fuel, or for the manufacture of oil, and for the 

 composition of which I may refer to the Laboratory Reports for 1868. 



Among Mr. Traill's specimens are also fragments of flints, and of a 

 calcareous rock resembling the chalk from Campbell Island. 



The older tertiary limestones are much changed by contact with volcanic 

 rocks, so that in part they are converted into true lithographic limestone, in 

 the same manner as occurs in the vicinity of Oamaru in Otago. 



The area of schistose rocks, exactly similar to the auriferous formation of 

 Otago is, in the Chatham Islands, very considerable ; and reef-quartz of several 

 varieties is represented in both collections, but no discovery of gold has yet 

 been reported. 



7. — Stewart Island. 



This island should not properly be classed with the small islands j)reviously 

 alluded to as outlying islands of New Zealand, but, as an extensive series of rock 

 specimens from it was forwarded at the same time with the other collections, 

 I will include the notice of them in this communication. The collection was 

 made by Mr. Walter H. Pearson, Commissioner of Crown Lands, Southland, 

 in the course of an official visit round the island for the purpose of ascertaining 

 where settlements could be advantageously placed. VVith reference to this 

 point, Mr. Pearson states in his report : — - 



* See " Trans. N. Z. Institute," Vol. i., p. 180. 

 t See " Trans. N. Z. Institute," Vol. i., p. 177. 



