Speight. — The Intermontane Basins of Canterbury. 35] 



all probability the land was of slight relief, or that the waters were sheltered 

 from violent currents and waves. 



However, in considering the question of the relief of the land as deduced 

 from the character of the deposit, allowance must be made for the situation 

 of the locality of deposition. Even on elevated coast-lines pebble beaches 

 are frequently absent for long stretches, and therefore it is perhaps inadvis- 

 able to be dogmatic on this point. 



It is found, however, that conglomerates form an increasingly important 

 feature of the beds succeeding the limestones, and towards the end of the 

 Tertian- era they dominate the sedimentaries. This is clearly seen in those 

 places where the Pliocene beds are well developed, such as in the lower 

 Waipara and Teviotdale districts and in the Mount Grey downs. The 

 abundance of coarse gravels indicates the existence of higher land in the 

 vicinity, but the strata containing them appear to be perfectly conformable 

 with the older beds of the Tertiary sequence. This increasing content of 

 Trias-Jura pebbles apparently indicates a rise of the land, but there is no 

 certain evidence of any structural unconformity between these beds and 

 the lower members of the Tertiary sequence. If the rise of the land had 

 occurred this should be forthcoming, certainly as regards shore deposits, 

 although it might be absent in the case of beds laid down in deep water 

 offshore. Some slight variation in the conditions controlling the land- 

 surface, rather than a great modification in the relief, would explain the 

 increasing importance of the coarser materials. 



After a careful consideration of the evidence, it seems fairly certain 

 that a land, probably in the form of islands, did persist in the North Canter- 

 bury area throughout Tertiary times, although it is quite possible that a 

 deep sea existed on the site of the Kaikouras, and that the deformations 

 which resulted in the formation of those great ridges were less pronounced 

 in the country to their south-west, and probably petered out in the mid- 

 district of Canterbury. 



There is another point which may be considered in this connection. 

 Micaceous sandstones are a frequent occurrence in the Tertian* beds of 

 North Canterbury, and the source of this mineral must be looked for else- 

 where than in the Trias-Jura rocks to the westward. Although a small 

 amount of this mineral occurs in these rocks as a detrital constituent, it does 

 not seem sufficient to account for the large amount contained in the derived 

 Tertiaries. Although it is a long way to the Chathams from the coast of 

 Canterbury, yet mica and other schists do occur in those islands, and there 

 may have been at one time a closer connection with similar rocks occurring 

 in New Zealand, and the existence of a submerged schist area which might 

 have furnished this material is by no means a remote possibility. If, how- 

 ever, we must look to the granite and schist areas on the west of the main 

 divide to have furnished this material, then the form of the land-surface 

 must have been entirely different from that which now obtains. 



The presence of a land connection with the Chatham Islands in«Tertiary 

 is absolutely necessary in order to explain the close resemblance of the fauna 

 and flora of these islands to that of New Zealand. Hutton suggested that 

 the land bridge was in existence in Pliocene times, though it broke up soon 

 after, this break being indicated by the fact' that some of the Chatham 

 Island species do show a considerable variation from their New Zealand 

 relatives ; and, further, there are species occurring in those islands which 

 have not been discovered on the main islands. He therefore considered 

 that the land connection was broken before the Pleistocene period began. 



