Canterbury and Westland. 385 



descending by the last mentioned pass was the most important, being 

 six to eight miles broad, and uniting again with the main glacier about 

 six miles above its terminal face. A division or forking of this 

 Hakataramea branch took place where now the upper waters of the 

 "Waihao are situated. The Burke's Pass branch was also of consider- 

 able size. It received a large addition from the Pox Peak range, 

 coming down by the valley where now the Opuha plains are situated. 

 A broad moraine was thrown across the valley of the Opihi, and a 

 river — with which some miles lower down the Mackenzie glacier 

 outlet united — issuing here from the terminal face formed high 

 and broad alluvial beds. These can be followed for nearly thirty 

 miles in a southern direction as far as the Otaio. The great 

 Waitaki glacier must have had in its middle portion, judging from the 

 terraces and roclies moutonnees situated here, a thickness of about 

 5000 feet. On some of these peculiar isolated ice-worn ranges in the 

 Mackenzie plains blocs perches are not uncommon. After a time this 

 glacier retreated and then maintained for a considerable period about 

 the same position. This phase may best be described as the Lake 

 period, because during it the rocks forming the bed of the glacier 

 were either excavated so as to form a true rock basin, or the terminal 

 and lateral moraines were heaped up so high, that when the glacier 

 retreated, the outlet flowed into the hollow thus made, forming a lake. 

 The retention of the water between the walls was doubtless assisted by 

 the enormous amount of silt, brought down below the glacier from higher 

 regions, by which the morainic accumulations were made impervious. 

 To this important epoch Lake Takapo, Pukaki, Ohau, and the large 

 swampy region in a similar position in the Ahuriri valley, owe their 

 existence. The sections ISTos. 4, 5, and 6 on plate 7 will give the 

 characteristic features of the morainic and other deposits surrounding 

 these lakes. The southern portion of Lake Pukaki lies entirely in 

 the plains. The morainic accumulations rise to 250 feet above 

 the level of the lake, whilst even in its northern or upper portion 

 where the slopes of the Ben Ohau range, either cut into by 

 glacier shelves or covered by lateral moraines, form its western 

 boundary, the eastern is still formed by the moraines. There is a 

 distinct series of old lacustrine beaches along the shores of Lake 

 Pukaki, rising about 200 feet, one above the other, clearly indicating 

 that after the retreat of the glacier the waters forming the lake stood at 

 a much higher level. There were several outlets, which were abandoned 

 when the central one cut its channel deeper int~> the frontal moraine. 



