50 Transactions. 



Zealand the parallelism in dip and strike of the Amuri limestone and the 

 succeeding Tertiary rocks is found throughout some hundreds of miles of 

 outcrop. 



In the Middle Clarence area the uppermost band of the Amuri limestone 

 is argillaceous, and passes quite gradually into fossiliferous Oamaruian 

 mudstones similar to the grey marls. The use of the term " grey marls " 

 hy Marshall, Speight, and Cotton (1911) for mudstones following the Ototara 

 limestone, and, in particular, for the Wanganuian mudstones of the 

 Wanganui River, has robbed this term of any geological significance, and 

 made it practicallj^ synonymous with Tertiary mudstone of any age or 

 position. Some of McKay's uses of the term in South Canterbury and 

 elsewhere are also equally unfortunate ; but as originally used by him 

 within the area occupied by the Amuri limestone it has a perfectly definite 

 significance — viz., for mudstones following the Amuri limestone — and if 

 confined to this usage it may continue as a most useful geological term. 

 It does not follow that by terming certain rocks the grey marls of the 

 Clarence Valley one necessarily considers them the correlatives of the grey 

 marls of the Waipara district, for the greater thickness of the Amuri lime- 

 stone of the Clarence Valley may be due not only to an earlier beginning, 

 but also to a later cessation of deposition than in the case of the lime- 

 stone at Amuri Bluff and the Waipara district. All that the term implies 

 is that they are mudstones following the Amuri limestone. 



On the theory of conformity between the Weka Pass stone and the 

 Amuri limestone, the age of the top beds of the latter can be fixed if the 

 age of the former is known ; but, although a considerable number of fossils 

 are known from the Weka Pass stone and the grey marls, the range of 

 these species within the Oamaruian is not yet well enough ascertained to 

 allow it to be stated whether these beds are Middle or Lower Oamaruian. 

 The Weka Pass stone certainly does not correlate with the Hutchinson Quarry 

 beds, as supposed by Marshall, since the main band of the Mount Brown 

 beds, containing Rhizothyris rhizoida and Pachymagas parki, occupies this 

 horizon in the Waipara district. The probabilities are that it will be found 

 that the Weka Pass stone correlates with the Waiarekan. 



It has apparently been assumed by the opponents of a conformable 

 Cretaceo-tertiary succession in any part of New Zealand that the whole 

 of the Amuri limestone is Cretaceous in age. Actually, however, the only 

 determinable fossils obtained from the limestone, excluding fish-teeth and 

 crinoid stems, are of Tertiary aspect. McKay has recorded Pecten zitteli 

 Hutt. and Rhynconella squamosa Hutt. from the limestone of Amuri Bluff. 

 The former species I have also collected from fallen blocks of the limestone 

 in the same locality, but the specimen identified as Rhynconella squamosa 

 is, in my opinion, not specifically determinable. In addition, Mr. H. Suter 

 has identified the following forms from the collections made by Mr. A. 

 McKay and myself from Amuri Bluff : — * 



Pecten zelandiae Gray. 

 Pecten delicat^ilus Hutt. (?) 

 Pecten sp. nov. of. P. chathamensis. 

 Pecten sp. nov. 



Pecten zelandiae is a Recent species, and its occurrence strongly 

 suggests that the rock from which it comes is of Tertiary age. Un- 

 fortunately, the exact horizon within the limestone of any of the above 

 forms is unknown. 



