Htjtton. — On the Silt Deposit at Lyttelton. 413 



widely extended a deposit, resting on such different rocks, could be formed 

 in the way suggested by Dr. von Haast ; and it is also difficult to under- 

 stand why, on this hypothesis, the deposit should be found only on the 

 coast near the mouths of the great rivers from the Waimakariri to the 

 Waitaki, and not elsewhere. 



In the second place the limit in height of the deposit must be noticed. 

 In the " Transactions of the New Zealand Institute," vol. vi., 1873, p. 423, 

 Dr. v. Haast says that on Banks Peninsula it extends to a height of 800 

 feet above the sea ; and in his Eeport on the Geology of Canterbury he says 

 that at Timaru it reaches to near the summit of Mt. Horrible, which is 

 1,272 feet high. No other data can be obtained at present, and the 

 difficulty here is to explain why, on the subaerial hypothesis, its height on 

 Banks Peninsula should be limited to 800 feet, notwithstanding that grass 

 grows, rain falls, and the wind blows at much greater altitudes. 



In the third place the silt deposit is not confined to the slopes. At 

 Oamaru it covers the very highest points of Oamaru Cape, as may be seen in 

 fig. 7, page 55, of my report already quoted ; and in many parts of Banks 

 Peninsula it is better developed on the ridges than in the valleys, as the 

 accompanying sketch of the cliffs between Little Akaloa and Mackintosh 

 Bay will show (fig. 2) ; so that the action of rain in its formation must be 

 eliminated. 



^ r ^\\\>- 



K^^tei&h&&*h 



Fig. 2, a, silt deposit ; b, volcanic rocks. 



The last point to be noticed is the fossils contained in tbe deposit. 

 Usually it is quite unfossiliferous, but Dr. von Haast states that moa bones 

 and land shells have been found in it somewhere on Banks Peninsula, but 

 no definite locality is named. The occurrence of land shells is remarkable, 

 considering how rare they are now in New Zealand, and that they are 

 almost entirely confined to the bush. I have never heard of any land shells 

 having been found on grass land except in crevices of limestone, or under 

 blocks of the same rock ; and there is no limestone on Banks Peninsula, 

 while, according to Dr. von Haast's hypothesis, the formation accumulated 

 on open grass land. 



At Oamaru marine shells of still living species are found in the lower 

 part of the deposit up to a height of 60 feet above the sea. A list of the 

 species will be found at page 70 of my " Eeport on the Geology of Otago," 

 1875. 



