386 Geology of 



They now form natural roads to reach the shores of the lake. The 

 frontal moraines of Lake Pukaki are about three miles broad, forming 

 -a series of walls enclosing each other. As we advance from the lake 

 towards their outer edge they gradually get lower, till at last only 

 here and there a chain of small hillocks, the upper portion of the last 

 visible moraine, appears above the alluvium. The same is the case with 

 the lateral moraines, showing a similar arrangement. Already abreast 

 of the central portion of Lake Takapo high ranges rise on both sides, on 

 the slopes of which the glacier has either cut deep shelves or thrown 

 its lateral moraines against them, now rising in steps nearly 2000 feet 

 above the level of the lake. Higher up in the valleys of the Tasman 

 and G-odley rivers these signs of former glacier power can be traced to 

 an altitude of nearly 4000 feet on the mountain sides, accompanied by 

 deposits of former glacier lakes, having stood at a high level. All these 

 phenomena present us with clear evidence of the enormous size and 

 power of the mighty ice-streams once descending here to lower regions. 

 Only in a few localities are there faint traces of frontal moraines 

 having been preserved in both these main valleys. They are more 

 conspicuous in the two main valleys forming the Hopkins river, the 

 principal feeder of Lake Ohau, as well as in the upper Ahuriri. 



The Eaeaia Glaciee. 



The glacier next in size has doubtless been the Eakaia glacier^ 

 having been at least of a length of 58 miles. The farthest point 

 down the Canterbury plains on which morainic accumulations are 

 visible is the so-called "Woolshed Hill, seven to eight miles below the 

 Eakaia G-orge. This hill rises about 100 feet above the plains, it has 

 a triangular shape, and consists of shingle and sand, from which in many 

 places angular blocks of sandstone, felstone and slates appear above 

 the surface. If we consider that the gigantic torrential rivers issuing 

 from the post-pliocene glaciers had the power of destroying easily beds 

 of such incoherent nature as the morainic accumulations, which barred 

 their passage, it is natural that only in very favourable cases such deposits 

 could have been preserved. It is thus evident that the lowest points 

 to which the post-pliocene glaciers reached are not always traceable, 

 but the occurrence of such isolated beds as the AVooished Hill so 

 far away from the principal morainic accumulations shows us that 

 we can scarcely fix the limits to which the huge ice-streams of the 



