Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/458

 sooner or later the cainozoic deposits of New Zealand, which attain probably a greater magnitude in depth than those of Australia, will be found to render the establishment of a great southern series necessary.

The Tertiaries of the North Island of New Zealand must be studied in relation to those of Australia. The great development of tertiary limestone between the Rangetoto range and the west coast of the North Island of New Zealand requires careful examination, especially as regards its fossils. Its relation to the lignites of what Hochstetter has called the Auckland Tertiaries, has been satisfactorily determined ; and by a comparison of the fossils with those from the Cape-Otway series a sufficiently satisfactory equivalency might be established ; so that a local terminology could be agreed upon, without binding geologists to the inevitable results of the adoption of the European classification of the succession of deposits during the tertiary period.

The polyzoan limestones of the North Island of New Zealand were probably the equivalents of the Mount-Gambier deep-water deposits. As yet no reef-building forms have been discovered in them.

The equivalency of all the cainozoic deposits described and noticed in this communication is probably as follows. The lowest bed, No. 1, 1/2 mile west of Cape Otway=the gravel- and boulder-deposit, and the old basalt of the inland valleys. Next in succession is No. 9, 3 miles west of the river Gellibrand, and then No. 4, clay-bed near Cape Otway, with Trigonia semiundulata. Nos. 9 and 4= the Hamilton tertiaries, the Geelong and Murray beds, below the so- called coralline limestone (with hardly a coral in it, but plenty of Polyzoa). Polyzoan limestone of Mount Gambier=No. 3, near Cape Otway. It often becomes more sandy as it overlaps the inferior but really contemporaneous deposits.

There are no neighbouring areas with whose strata these can be correlated. The tertiary formation of Java has been magnificently illustrated, so far as its corals and Echinodermata are concerned, by Reuss and Herklots ; but it was deposited under the conditions peculiar to a reef-area. The fossil corals were reef-building, and had the old-fashioned facies which is characteristic of the Australian fauna.

The palaeontology of the coral limestones of the coasts of the great islands to the east of New Holland is a blank ; and even the great raised reefs of the Sandwich Islands have not been studied. The Caribbean tertiaries have hardly anything in common with the Australian, and were deposited in a reef-area. With these considerations and facts before us, the necessity for a critical examination of the New-Zealand Tertiaries becomes most urgent.

At present all that can be arrived at concerning the relative position of the Australian fossiliferous Tertiaries and their physical geology may be quickly summed up. They were formed on a sea-bottom of the oldest rocks, in increasingly deep water, during a period when the denudation of the neighbouring coast-line to the east and north- east was rapid. They were very distant from the reef-area of the