Canterbury and Westland. 205 



South of Lake Ohau, the Ahuriri enters into the southern continua- 

 tion of these plains where, for five or six miles, its bed is of great 

 "breadth (in the so-called Ahuriri plains) after which the rocky ranges 

 approach close to each other again, forming a deep gorge which 

 continues to its junction with the Waitaki. In the fork of the two 

 rivers, Ben More, an isolated range, rises conspicuously, which during 

 the Great Glacier Period stood as an island above the ice-masses, and 

 along the eastern and southern base of which the two rivers have 

 excavated their deep rocky gorges. The Waitaki, below this junction 

 flows for 17 miles, generally confined to one channel, untih two 

 miles above the junction of the Hakataramea, the valley opens up, the 

 river however, continuing to flow generally in one body, or if divided 

 into two or more branches, it still has only a narrow bed. Nineteen 

 miles below the junction of the Ahuriri, the Hakataramea river joins 

 the Waitaki from the north. It is by far the most important tributary 

 below the former, no other streams of any consequence joining it on the 

 Canterbury side. On the southern or Otago side, only small affluents 

 reach it, of which the Otomatakau and Marawhenua are the most 

 important. Seventeen miles below the junction of the Hakataramea, 

 the mountains recede on the northern side of the valley, which now 

 opens up still more, the old alluvial deposits on both sides, which 

 hitherto had only been narrow, become wider, the bed of the river 

 itself also gradually enlarges, forming a number of anastomosing 

 branches. The further we advance towards the coast, the more 

 characteristic these features become. A series of small terraces are 

 also formed without, however, ever assuming the vast proportion of 

 the terraces in those rivers which have formed the Canterbury plains. 

 The reason of this absence is obvious, the "Waitaki glacier, during the 

 Great Griacier period, being of such enormous dimensions that it reached 

 far below the mouth of the Hakataramea, and stood at such a high 

 level that the bed of the gigantic river issuing from it, Fas flowing 

 seven or eight hundred feet above the present valley. Thus, the whole 

 valley up to that altitude was covered with alluvial deposits, and 

 although the period during which these beds were formed, is separated 

 from us by a short space of time, geologically speaking, the size of the 

 river was still so enormous that when the glacier after repeated 

 oscillations, at last gradually retreated, it had so effectually destroyed 

 its former bed that only here and there on the summits of the ranges 

 between the Waihao and lower Waitaki, small portions of that 

 alluvium were preserved, so that no terraces of any size could be 

 formed. 



