106 Transactions. 



Cretaceous (Amuri) and a Miocene (Oamaru) division. A similar difference 

 in the age of the basement rocks in Westland caused Morgan to separate 

 the Eocene (Waimangaroa) and Oamaru (Miocene) formations in Westland. 

 It was stated by Marshall, Speight, and Cotton, that this difference in 

 the age of the basement beds in various sections was the necessary overlap 

 of the younger over the older members of a conformable series deposited 

 during a prolonged period of depression dixring which the downward move- 

 ment was more rapid than the building-up by the accumulation of sedi- 

 ment. This rapid depression caused the series to be deposited in the 

 following order of succession : — 



(4.) Limestones. 



(3.) Grpensands. 



(2.) Sands. 



(1.) Conglomerates. 



It was held that the stratigraphical and the lithological evidence were 

 perfectly definite, but it was admitted that at that time there was no 

 palaeontological evidence in support of the position taken up by the authors. 

 So far as palaeontological work had gone, it appeared that the Cretaceous 

 fossils at the base of the series were quite distinct from the Miocene fossils 

 in the higher members of the series, and, so far as known, could not even 

 be regarded as an ancestral fauna of the latter. 



At that time, however, the Cretaceous fauna had never been described p 

 but that great gap in our knowledge has now been partly filled, for Mr. 

 H. Woods has recently described the collections of lamellibranchs and 

 cephalopods from Amuri Bluff and other typical Cretaceous localities. His 

 work has not yet been published, but it is understood that he classes the 

 Amuri Bhiff, Waipara, and Selwyn Rapids beds in the Senonian.* 



The knowledge of the Tertiary fauna was also in an unsatisfactory state, 

 because the types had not been figured, and for the most part they were 

 not available for study, and the collections had not been closely defined as 

 to locality and horizon. Specific identification was therefore inexact, and 

 it was impossible to find in many places in what portion of a series the 

 fossils had been collected — -whether from sands, greensands, limestones, 

 or marls. 



Within the last few years extensive collections have been made in 

 definite horizons in various districts — -Clarke in the Waitemata beds of 

 Auckland, Speight in the lower Waipara Gorge, Gudex at the Blue Clifi's 

 in South Canterbury, Marshall and Uttley at many localities near Oamaru. 

 These collections have shown that the division of these Tertiary rocks into 

 Upper Miocene, Lower Miocene, Eocene, and Cretaceo-tertiary by Hector, 

 and into Oligocene and Miocene by Hutton, and into various divisions of 

 the Miocene by Park need considerable revision. 



Hutton had previously drawn attention to the close relationship between 

 his Miocene (Pareora) and Oligocene (Oamaru) formations by stating 

 that, of 268 species of Mollusca found in the Tertiary series, thirty-three 

 species were restricted to the Oamaru, and 184 species to the Pareora, while 

 fifty-one species (a percentage of 19) were common to the two formations ; 

 or, of the eighty-four species of the Oamaru, as much as 60 per cent, occur 

 in the Pareora. Marshall, in fairly complete collections near Oamaru, finds 

 in the greensands of Wharekuri, below the limestone, fourteen Recent 



* N.Z. Pari. Paper C.-2, Geol. Surv., Ninth Ann. Rep. (n.s.), 1915, p. 76. 



