HuTTON. — The Geological History of New Zealand. 173 



Hawke's Bay/'' However, it probably occurs also at Tara- 

 naki, Poverty Bay, and several other places in the North 

 Island. 



In the South Island the marine rocks of the north appear 

 to be represented by thick beds of unfossiliferous gravels 

 deposited by mountain torrents, some of which may date 

 back to the close of the Miocene. 



Of volcanic rocks we may probably assign the rhyolites 

 of Tarawera, Eotorua, and the Thames Peninsulat to the 

 Pliocene period, as well as the hornblende and augite-ande- 

 sites which form the bases of Pvuapehu and Mount Egmont. 

 But very little is known about the sequence of the volcanic 

 rocks of the North Island. 



The Great Glacier Epoch. 



We now come to one of the most interesting phases in the 

 geological history of New Zealand — I refer to the great glacier 

 epoch. Ancient glacier-marks, principally in the form of 

 terminal moraines, are numerous in the South Island, and 

 they are no doubt of various ages. But it remains uncertain 

 whether they form a single continuous and diminishing series 

 from the earliest records to the present day, or whether there 

 have been two or more periods of marked extension of the 

 glaciers. The most northerly glacier-marks are found round 

 Mount Olympus and the Arthur Eange, in Nelson. None 

 have been recorded from the Kaikoura Eauges, although at 

 the present day they are capped with perpetual snow, and 

 none are known in the North Island. The St. Arnaud and 

 Spencer Mountains gave origin to many glaciers. The prin- 

 cipal ones on the northern side of these ranges filled the 

 valleys now occupied by Lakes Eotoiti and Eotorua (of the 

 Nelson Provincial District), while to the south and east large 

 glaciers went down the Clarence and the Waiau-ua, the latter 

 being no less than fourteen miles in length. The ancient 

 glacier of the Waimakariri was thought by Sir Julius von 

 Haast to have extended for a length of fifty-four miles, 

 reaching out on the Canterbury Plains as far as Sheffield. 

 This view is open to several objections, but it seems to be 

 certain that the Eakaia Glacier, at the time of its greatest 

 extension, debouched on to the Canterbury Plains, and 

 stretched nearly as far as Woolshed Hill, which would give 

 it a length of about fifty-five miles. Less is known about the 

 ancient glaciers of the Eaugitata and Waitaki ; but in Otago 

 that of the Clutha certainly came as far as the Lindis, and 

 perhaps to Cromwell, which would give it a length of about 



* Trans. N.Z. Inst., vol. xviii., p. 336. 



t James Park, Quart. Journ. Geol. Soc. London, vol. 55, p. 451. 



