Physiography, Geology.] SUBANTARCTIC ISLANDS OF NEW ZEALAND. 



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extensive area has been covered by these rocks, and they may be of the same age as 

 the porphyrites and diabases from Macquarie Island described by Marshall,* and also 

 by G. T. Prior.f Some of the specimens got from the end of Musgrave Peninsula, so 

 strongly resemble certain of the recent basic series that they may well belong to it. 



One interesting discovery was the occurrence of a thin bed of impure anthracite 

 between two flows. This had a distinct metallic lustre, and the rough columnar 

 structure frequently observed in cases where sedimentary rocks have been subjected 

 to contact metamorphism. This, no doubt, has been formed from a coating of 

 peat which has been coked by the heat of a superjacent lava-stream ; when burnt 

 it left a large quantity of reddish ash. Its occurrence is noteworthy, as showing 

 that even in the period of volcanic activity peat occurred over parts of the country, 

 proving that the climatic conditions were in all probability the same then as now ; 

 and, further, that the volcanic flows were not submarine, and that a land surface 

 existed in the locality at the period of volcanic activity. There are also persistent 

 reports that similar deposits of such coal occur in the north-western part of the 

 group. 



In connection with this occurrence of peat turned into coal, it may be mentioned 

 that Captain Bollons, of the Government steamer " Hinemoa," presented a member 

 of the expedition with a piece of coal from Antipodes Island. It shows the effect 

 of heat, in that it is hard and has columnar jointing, but the peaty structure is still 

 quite apparent. Moseley, in his " Notes by a Naturalist " (p. 173), mentions the 

 occurrence of coal between basaltic flows at Kerguelen Land, and his description 

 would exactly fit the occurrence at Carnley. 



The oldest rock of the series is a typical diabase, but the most common rock 

 is a diabase-porphyrite, which has the following composition, the analysis having 

 been made by Mr. A. M. Wright : — 



Per Cent. 

 SiOa .. .. .. .. .. .. 47-41 



16-18 



AI2O3 



Fe^Og 



FeO 



MnO 



TiO, 



CaO' 



MgO 



K,0 



Na^O 



COo 



Water lost below 100° C. (H.,0 -) 

 above 100° C. (R10 + ) 



Specific gravity 



12-92 

 8-37 

 0-27 

 0-31 

 4-03 

 1-16 

 2-15 

 3-49 



Trace 

 0-21 

 1-42 

 1-38 



99-30 



2-80 



* " Some Rocks from Macquarie Island," Rep. A.A.A.S., vol. x, 1904. 

 t G. T. Prior, Nat. Ant. Exped., Geology, p. 109. 



