322 Transactions. 



This comprises all that has been written on the locality, and the present 

 paper is an attempt to add to the record of fact in regard thereto, especially 

 in its bearing on the conformity of our Tertiary series. 



The situation of the basin almost midway between the classic districts 

 of Aniuri Bluff and Waipara on the one hand, and Pareora and Oamaru 

 on the other, adds to its interest and importance and value as a critical 

 locality, even though its stratigraphy is complicated by volcanic action 

 and by structural movements. It may be urged that if the resolution of 

 our problems of conformable or unconformable succession are a matter 

 of such serious difficulty in areas where these disturbing factors do not 

 exist little help can be obtained from such a disturbed area. There are 

 some features, however, which render it peculiarly useful for study in this 

 connection. The position taken by the author in this paper is that the 

 locality has not furnished up to the present any positive evidence of uncon- 

 trovertible value of the physical unconformity in the Tertiary sequence ; 

 but this statement is not to be interpreted as indicating that none will be 

 subsequently demonstrated. There are difficulties which can be explained 

 on a basis of unconformity, though other explanations are equally ap- 

 plicable ; but the position of the breaks will be chiefly determined on 

 palaeontological grounds, and in order to do this it is necessary that 

 systematic and complete collections be made from well-defined horizons. 

 Great as were the services rendered to New Zealand science by Mr. J. D. 

 Enys during his residence in this remote locality, he would have materially 

 helped geological investigation had he realized the importance of this point. 

 It is extremely unfortunate that his collections were inadequately labelled 

 as regards place of origin, and the result is that the fine collection of New 

 Zealand fossils in the Canterbury Museum identified and described by 

 Hutton — many of them types — cannot be assigned with certainty to a 

 particular bed, such indefinite place-names as " Porter River" or " Broken 

 River " conveying little information of value from the standpoint of 

 stratigraphical geology. 



This deficiency has been remedied to some extent by the kindness of 

 Dr. Allan Thomson, who has furnished me with a list of the fossils collected 

 by McKay and at present in the Geological Survey collection, as well as a 

 list of those collected by Enys ; also of the fossils collected by himself in 

 conjunction with the author in November, 1914- — all recently identified 

 by Mr. H. Suter. The last-named has most kindly identified for me a 

 number of specimens collected in the summer of 1915-16. 



B. GENERAL PHYSICAL FEATURES. 



The general physical features of the district have been described by both 

 McKay and Hutton in their accounts of its geology, and a reference to the 

 origin of the basin has been made by myself in the paper on the inter- 

 montane basins of Canterbury referred to above. The general sequence 

 of events indicated therein is as follows : The Trias-Jura sedimentaries, 

 of which the encircling mountains are composed, were folded by lateral 

 pressure into a mountain area probably in early Cretaceous times. This 

 was reduced to a peneplain by the end of the period, or perhaps a little 

 later, and the land was then depressed below sea-level, the submergence 

 continuing during the greater part of the Tertiary era, and on the eroded 

 surface of Trias-Jura rocks a series of sedimentaries, including sands, green- 

 sands, limestones, calcareous sands, and conglomerates, were laid down in 



