. Transactions and proceedings of the New Zealand Institute . holocrystalline and glassy. Theglassy type is formed almost entirely of a dark-brown glass with incipientcrystallization in black semi-opaque patches. There are no crystals ormicrolites present. The holocrystalline rocks are somewhat diabasic in structure, oftenophitic, with relatively little olivine, which is nearly completely changedinto serpentine. The feldspar is mainly labradorite much augite is nearly colourless, and is always allotriomorphic. Iron-ore isplentiful, apparently entirely ilmenite. These two types c
. Transactions and proceedings of the New Zealand Institute . holocrystalline and glassy. Theglassy type is formed almost entirely of a dark-brown glass with incipientcrystallization in black semi-opaque patches. There are no crystals ormicrolites present. The holocrystalline rocks are somewhat diabasic in structure, oftenophitic, with relatively little olivine, which is nearly completely changedinto serpentine. The feldspar is mainly labradorite much augite is nearly colourless, and is always allotriomorphic. Iron-ore isplentiful, apparently entirely ilmenite. These two types closely resemblethose that are found at Oamaru, where also they are interbedded with thelimestone of Tertiary age. They have been described by Hutton.* Huttonfalso describes several other glassy types of a similar nature. He afterwardsstates that the rocks occur interstratified with sedimentary rocks of Oamaruage at intervals from Look-out Point, near Hampden, to Castle Hill, adistance of 150 miles.| McKay and Sollas describe similar types from the HICK* BAY. Maftaisystem Mason River, in South Nelson, where again they are interistratified withlimestone rocks of Oamaru age.§ It thus appears that over a wide extentof the eastern coast-line of New Zealand submarine eruptions of a basicnature occurred at the time when the limestone of Oamaru age was under-going deposition. It has been suggested in another paper that the lime-stone of this series was deposited approximately at the same time throughoutNew Zealand, and that it was laid down when the country had reached itsmaximum of physical depression .|| If this be the case, it is evident that thiswidespread series of submarine eruptions was practically simultaneous,and ushered in a period of general epeirogenic elevation in the New Zealandregion. * Trans. Inst., vol. 19, 1886, p. 417. t Jour. Rov. Soc. , 1889, p. 152. % Trans. 1SLZ. Inst., vol. 32, 1899, p. 170. § Rocks of Cape Colville Peninsula, vol. 2, p. 168. i| Tra
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