102 



T ransa ctions . 



Above the junction of the two branches the evidence is undoubted, 

 especially from the vicinity of the Lakes Station and Lake Sumner towards 

 the head of the river. Old moraines, smoothed and rounded surfaces, and 

 the form of the cross-section' of the valleys furnish indubitable evidence of 

 the former presence of ice. In the upper part of the course of the North 

 Branch the even alignment of the valley-walls, their steep lower slopes 

 and gentler upper ones, the truncated and semitruncated spurs, and the 

 roches moutonnees on the valley-floor are as characteristic of the results of 

 glaciation as anything in the valleys of the Southern Alps farther south. 

 On the north side of the river the mountain-tops have a very flat plateau- 

 like form, and this feature continues as far as the valley of the Waiau, if 



n 



L/A/E.S OF C///£:/ r G LAC ML. STtfgAMS 



Fig. 2^— Upper Hurunui Valley. 



not|farther,^so that the streams run in deep trenches incised in the table- 

 land. To the south of the river the mountain-tops are more like those 

 characteristic of middle and southern Canterbury, with rugged summits 

 and wide expanses of moving debris dislodged from solid rocks by the action 

 of frost. To the east of the plateau region the mountains take on this form 

 even to the north of the river. 



Specially interesting features of the river-basin have resulted from 

 the action of these ancient glaciers on a mature valley-system which had 

 become established in pre-glacial times. These features are so strongly remi - 

 niscent of those of the valleys farther south, especially of the Waimakariri, 

 that thev must be attributable to a common cause. The only difference in 

 the two cases is that the features of the Hurunui are not so strongly marked, 

 which is no doubt due to the more moderate intensity of the glaciation in 

 the northern river. Thus there are distinct traces of the original directions 

 of the streams, which are wanting farther south, but which may give some 

 clue to the origin of the characteristic features of the valleys. 



Parallkl Valley System of Upper Part of Basin. 



The most striking landscape form of the upper basin of the Hurunui is 



the series of subparallel valleys flanking the North Branch on its southern 



side. These are quite analogous to those of the Waimakariri, also on its 



southern side, and to those in the vicinity of Lake Coleridge in the valley 



