808 Transactions. — Geology. 



In June 1875, Mr. S. H. Cox, in his report on the Eaglan and Waikato 

 districts, * said that the sandstones and clays of Mercer were probably the 

 equivalents of the Waitemata series, and he considered them to form part 

 of Dr. Hector's cretaceo-tertiary formation, now called the " Waipara 

 Bystem ; " at the same time saying that " the fossils do not absolutely fix 

 them as such." This is certainly very true, for the only fossil in his list 

 of any chronological value is Dentalium nanum, Hutton, which is found in 

 the pliocene beds at Wanganui and Petane. In his further report, however, 

 Mr Cox says that " they are in this locality the higher member of the Leda 

 marls. "t In 1879 Mr. Cox was sent to examine the country from Auckland 

 northwards ; tracing the Waitemata series towards the Kaipara and Cape 

 Bodney, he found that it gradually changed into greensands mixed with 

 much volcanic ash, and that at Mahurangi and at Komiti Point, in the 

 Kaipara District, it rested unconformably on " chalk-marls and hydraulic 

 limestones," thought to be of cretaceo-tertiary age. This, together with the 

 fossils found at Komiti in the Waitemata series, led him to alter his former 

 opinion, and to consider the Orakei Bay Beds as lower miocene.| Dr. 

 Hector in his Progress Beport for the same year demurs to this conclusion 

 and suggests that the Waitemata series ought to be divided at the horizon 

 of a volcanic ash bed in the cliffs under Parnell, which he calls the " Parnell 

 Grit;" all below this bed, including the strata at Orakei Bay, being still 

 retained as cretaceo-tertiary : his reason being that Pecten zittelli, Hutton, § 

 and many other Orakei Bay fossils are found at Komiti Point only in sandy 

 marls and grits which underlie tufaceous beds containing a number of 

 lower miocene forms. || Mr. Cox, however, who collected the fossils, says 

 distinctly in his report that " these beds [i.e., the marly grits] curiously 

 enough contain, associated with a great preponderance of lower miocene forms, 

 the Pecten zittelli, Hutton, and P. fischeri, Zittel, of Orakei Bay, on the 

 occurrence of which we have ascribed a cretaceo-tertiary age to these beds, "11 

 and he does not mention any fossils in tufaceous beds. 



In the following year Mr. Cox was sent to re-examine this point, but he 

 reported that he was more than ever convinced of the correctness of his last 

 year's work, although he thought it possible that the Waitemata series 

 might be of eocene age.** He examined the cliffs from Auckland to Orakei 



* Eeports of Geological Explorations, 1874-76, p. 9. 



t Eeports of Geological Explorations, 1876-77, p. 22. 



I Beports of Geological Explorations, 1879-80, p. 37. 



§ Dr. Hector and Mr. Cox often call this shell Pecten pleuronectes ; it seems therefore 

 necessary to point out that P. pleuronectes, L., is a living species which has never been 

 found in New Zealand. 



|| I.e., p. xii. M I.e., p. 17. On page 33 he gives a list of these fossils. 



** Probably influenced by his mistake of supposing that nummulites occur at Orakei 

 Bay. (Beports 1879-80, p. 25.) 



