112 Transactions. 



Such a succession can be found near the Waihao Forks. Here the green- 

 sand strata that are exposed on the right bank of the river, between 

 the Forks and McCuUoch's bridge, are similar lithologically to the Hamp- 

 den beds, and there is a clear stratigraphical succession to the local 

 representative of the Oamaru limestone above, as has been clearly shown 

 by McKay, Park, Marshall, and all others except Hutton, who gave a 

 most surprising account of the stratigraphy. Not only are the Waihao 

 greensands similar lithologically to the Hampden beds, but there is also a 

 close palaeontological similarity, for the following fossils which have not 

 yet been found in any higher or, indeed, any other strata occur in both 

 of them — Polinices waihaoensis, Exilia waihaoensis, Turris regius, Turns 

 complicatus, Surcula serotina, Fusinus solidus, and Eiithriofusus spinosus — 

 though up to the present time only very small collections have been made 

 in the Waihao beds. The Hampden beds may therefore be considered as of 

 much the same age as, though perhaps a little older than, those at Waihao. 

 In this locality, however, the stratigraphy is not complicated by the occur- 

 rence of any strata of volcanic origin, and the greensands pass up without 

 any break, and within a thickness of 100 ft. of strata, into a limestone 

 which is thought by all observers except Park to be the local representative 

 of the Oamaru limestone. No collection of fossils has yet been made from 

 the limestone at the Waihao, but at Otiake, twenty miles distant, on the 

 south side of the Waitaki River, there is a similar limestone, which is con- 

 sidered by all geologists who have examined this area to be of the same 

 age, and in effect a continuation of the limestone stratum of the Waihao. 

 At Otiake a collection of fossils was made by Marshall and others, who 

 found sixty-one species, of which 24 per cent, were determined as Recent 

 species. 



The facts so far mentioned may be summarized as follows : At Cole- 

 ridge Creek, in the Trelissick Basin, there is a fossiliferous horizon con- 

 taining 19 per cent, of Recent species. This horizon is below the limestone 

 (Speight, 1917, pp. 328 and 344), or 10 ft. below the upper surface of the 

 Amuri limestone (Thomson, 1916, p. 51). In the greensands at Hampden 

 there are 10 per cent, of Recent species. Lithologically and palaeonto- 

 logically the Hampden beds are closely similar to those at the Waihao 

 Forks, which pass up conformably into the arenaceous limestone. This 

 limestone is always correlated with that at Otiake, which in its upper 

 portion of 2 ft. or 3 ft. contains 24 per cent, of Recent species. 



Such palaeontological evidence as we have at present therefore clearly 

 points to the probability that the age of the Amuri limestone as developed 

 in the Trelissick Basin is practically the same as the age of the Otiake lime- 

 stone, which is admitted by all geologists except Park to be the same horizon 

 as that of the Oamaru or Ototara limestone. 



This consideration also shows that too much importance should not be 

 attached to the absence of the Amuri limestone in Otago. This material 

 is a Globigerina ooze, which was probably deposited on the floor of a deep, 

 clear- water, oceanic area. The Oamaru or Ototara limestone was deposited 

 in far shallower water, where Polyzoa abounded, but still outside the area to 

 which sediment was carried. The Waihao and Otiake limestones, however, 

 were deposited nearer to the shore, in an area to which terrigenous sediment 

 was carried, and where tidal scour disturbed the sea-floor. 



It seems unnecessary to call in the aid of local diastrophes to explain 

 the difierences between the Canterbury and Otago succession of Tertiapy 

 rocks, for, as I have often maintained, the differences that exist can easily 

 be explained on general considerations. The Canterbury area was evidently 



