Thomson. — Stage Names applicoble to Divfxwns nf Tertiary. 31 



(3.) By Marshall (1911) for the Avhole of the Tertiary sequence at Oamaru 

 and its correlatives, and also for all other beds which in other parts of New 

 Zealand are conformable with those correlatives. Marshall included the 

 Cretaceous beds of the Waipara and Aniuri Blufi districts in the Oamaru 

 system because he considered that they lay conformably beneath Tertiary 

 beds correlative with those at Oamaru. 



Since I am not here concerned with the validity or otherwise of an 

 Oamaru system, these three usages need not be discussed in that light ; 

 but it may be suggested that for a system such as Marshall believes to 

 exist the term " Waipara system " would be preferable on geographical 

 grounds, for all the beds he places in it, including those at Oamaru, have 

 correlatives at Waipara. Park used such a geographical principle in 1910 

 when he replaced his Oamaru system of 1905 by a Karamea system, which 

 included not only his former Oamaru system (now Oamaru series), but 

 also lower beds without correlatives at Oamaru (Waimangaroa series). 

 This is, I believe, a sound principle to follow wherever possible in the use 

 of geological terms derived from place-names. To me, then, " Oamaruian " 

 denotes the whole Tertiary succession as developed at Oamaru, and its 

 correlatives elsewhere, but no other beds. This use of the term fortunately 

 coincides in extent with its former application by Park. 



There is, however, a subtle but important difference between his usage 

 and that which I now propose. In speaking, for instance, of the Weka 

 Pass stone, the grey marls, and the M^unt BroAvn beds of the Waipara 

 section as Oamaruian we both mean that these beds are the correlatives 

 of the beds at Oamaru ; but Park means also that they are unconformable 

 with the underlying and overlying beds, whereas I express by the term 

 no opinion on the point. In other words, Park's use of the term is 

 systematic, while mine is geographical. I make the plea for such a geo- 

 graphical use of stage names terminating in " ian " as tending to bring 

 about a greater uniformity of nomenclature. 



II. Stage Names derived from the Oamaru District. 



The Oamaruian, as above defined, consists of a series of rocks to the 

 members of which we may apply stage names with advantage. Thus the 

 European Miocene, with which the Oamaruian is sometimes correlated, has 

 been divided into six stages. It is not contended that the stages here 

 proposed are of the same value as those of the European Miocene : that 

 will be an interesting point to discuss when we are in a position to do so. 

 All that is claimed is that these divisions can be recognized at Oamaru 

 and the neighbouring districts, and probably will be capable of identifi- 

 cation throughout New Zealand when our knowledge of the faunas is 

 more complete. Incidentally, the recognition of distinct stages will throw 

 into relief our lack of knowledge of some of these faunas. 



The succession of rocks at Oamaru is somewhat varied in different 

 localities within the district owing to the unequal development of volcanic 

 rocks at different points, and some difference of opinion exists as to the 

 actual order of succession. The difficulty is in reality palaeontological 

 more than stratigraphical, and is explained by the fact that the fauna of 

 the beds underlying the Ototara limestone and its correlative the Waihao 

 limestone resembles that of the beds overlying the limestone more closely 

 than that of the limestone itself. This is due, no doubt, to the similarity 



