386 Transactions 



and, althougli it is usually more marly than the Amuri limestone of the 

 coastal district, it is in places quite indistinguishable lithologically from it. 

 Speight (1917a) has accepted this correlation. Now, however, from an 

 examination of Foraminifera from two localities, Mr. Chapman considers that 

 it is "probably Eocene." If this view is confirmed, it certainly demands 

 an unconformity between this rock and the underlying Piripauan beds — an 

 unconformity of which Speight was unable to find any trace. Nevertheless, 

 in view of Chapman's correlation, it is unsafe to take into accoimt the 

 molluscan fauna referred to above in attempting to correlate the Amuri 

 limestone of the Waipara or Amuri Bluff. 



Chapman's identifications of the Foraminifera make it quite clear, how- 

 ever, that Marshall's correlation of the Amuri limestone with the Ototara 

 limestone is mistaken. On the basis of the Foraminifera Chapman declares 

 the Amuri limestone Danian, and the Weka Pass stone and " grey marls " 

 Eocene. On the same basis Marshall declares the Ototara limestone Miocene. 

 The correlative of the Ototara limestone in the Waipara section must, then, 

 lie above the " grey marls," and this accords well enough with the evidence, 

 to be discussed later, from the molluscs and brachiopods. 



Outside the area north of the Rakaia River there is no limestone in the 

 South Island that can be correlated with the Amuri limestone. It appears, 

 however, to be present in east Wellington, and to be represented in North 

 Auckland by the hydraulic limestone of the Kaipara and Whangarei dis- 

 tricts. Marshall (1919) has remarked that I have objected to this correla- 

 tion ; but what I objected to in 1917 was his correlation of the Whangarei 

 polyzoan limestone with the Amuri limestone by first correlating the Wha- 

 ngarei polyzoan and hydraulic limestone. I merely pointed out— and it is 

 still true — that no palaeontological or stratigraphical evidence has been 

 presented for the correlation of the Anauri limestone and the hydraulic 

 limestone of the Whangarei district. Marshall the same year supplied the 

 evidence so far as the hydraulic limestone of the Kaipara was concerned, 

 and there is no reason to doubt that the hydraulic limestone of the two 

 regions is the same. I do not agree, however, that the Whangarei poly- 

 zoan limestone is of the same age or older, any more than is the limestone 

 of Gibraltar Rocks, in the Kaipara district. I have observed Oamaruian 

 mollusca below the polyzoan limestone of Horahora, and have little doubt 

 that both it and the Gibraltar Rocks limestone are Oamaruian. The 

 geological survey of this district, however, which is at present in progress, 

 will doubtless settle this point. 



OAMARUIAN. 



The age of the Oamaruian has been commonly accepted as Miocene for 

 some years, very largely on accoimt of Chapnlan's determination of the 

 Foraminifera of Waikouaiti Head, and his demonstration of the Miocene 

 age of the older Tertiaries of Australia. Having never been willing to 

 admit that the contact of the Amuri limestone and the Weka Pass stone, 

 though doubtless a disconformity, could bridge the gap between Cretaceous 

 and Miocene, I formed the opinion -either that the Amuri limestone must 

 include the Eocene or that the Oamaruian ranged down from Miocene to 

 , Eocene ; and a large part of my explorations for several years past have 

 been directed to obtaining direct evidence of the age of the Amuri lime- 

 stone, and to ascertaining the faima of the lower members of the Oamaruian. 

 In 1915 I endeavoured to show that the beds at Waikouaiti from which the 

 Foraminifera described by Chapman as Miocene were obtained were upper 

 Oamaruian. There can be no doubt from the lists of fossils I have quoted 



