88 Transactions. 



the present shore-line. It would be expected that they should occur some- 

 where. Present-day shore-lines show surfaces of Amuri limestone with 

 no similarity whatsoever to those associated with the nodular layer, even 

 when those parts of the shore-platform are composed of nearly horizontal 

 layers. Any change in the nature of the rocks due to folding and conse- 

 quent induration which might be cited from the Kaikoura neighbourhood 

 as modifying the conditions would not apply farther south, where the 

 influence of such movements has been comparatively slight. 



3. There is no true shore or shallow-water deposit of any kind over 

 the whole area. It is certain that during the depression demanded by 

 the unconformists, when the surface of the Amuri limestone was lowered 

 from forming part of a land surface or a shore-line to such a level that 

 glauconitic limestone and greensand were deposited, beach and shallow- 

 water beds would occur in some parts of the area. Nevertheless they are 

 absent entirely. 



4. In many places is it impossible to determine the dividing plane between 

 the two limestones, so gradual is the transition — that is, they furnish in some 

 places no evidence of a break. In fact, as a general rule the upper and 

 lower layers display such a similarity in their characters, notably in the 

 presence of glauconite, that transitional forms are to be expected. 



5. In the case of the borings in the upper surface of the Amuri limestone, 

 and also those in the Weka Pass stone in contact with the grey marl, the 

 borings are filled with the material of the overlying bed, however deep they 

 are down below the surface. If this is a greensand the tubes are filled with 

 oreensand, if a marl they are filled with marl. Also, there are cases of 

 tubes in the body of the limestone which are filled with the material being 

 laid down on the surface into which the borings were made. If, now, these 

 borings were made on an ordinary beach or shore -platform they would be 

 filled with beach deposit, and would not remain open till they were de- 

 pressed to a depth at which limestone or greensand was the characteristic 

 deposit. 



6. The remarkable uniformity in the thickness of the layer over long 

 distances appears to be inexplicable on the basis of its being a shore-line 

 deposit, since these are notably variable both in thickness and in the nature 

 of their constituents. The parallelism of the upper and lower surfaces of 

 the layer is well brought out in the photographs taken from various widely 

 separated localities where the bed is well and clearly exposed. 



7. The analyses of the so-called " rolled pebbles " at the junction between 

 the two layers (see page 71) shows that they are not ordinary detached 

 fragments of Amuri limestone such as would be found on a beach, which 

 should resemble the parent rock in chemical composition. They have cer- 

 tainly been modified by agencies other than those operating on a shore-line. 



Morgan (1915, p. 92) cites a paper by Edward M. Kindle on " The 

 Unconformity at the Base of the Onondaga Limestone in New York, and 

 its Equivalent West of Buffalo";* and remarks, "This paper describes 

 fully an unconformity not easily detected at all points by stratigraphical 

 evidence alone." He uses it to emphasize the fact that an unconformity 

 can occur between two limestones. But it seems to us that such contacts 

 are by no means unlikely, since limestones of various ages form a notable 

 feature of the rocks of the earth's crust, and the probability of a contact 

 between two limestones as compared with that between limestone and 



* Journ. Geol, vol. 21, pp. 301-19, 1913. 



