262 Ancient Glaciers of New Zealand. 



were carried over its terminal face — just as trees and blocks 

 of ice are carried over Niagara — and were left as the con- 

 fused mass that we now find. 



Some idea of the time required for this truly herculean 

 task of valley-making, may be gathered, perhaps, from the 

 fact that the average motion of the Swiss glaciers can be 

 taken at about twelve inches a day, or one mile in fourteen 

 and one-half years. At this rate, a block of stone falling 

 upon the glacier of Lake Wakatipu near its source at Mt. 

 Earnslaw, would require more than a thousand years to reach 

 its final resting place in the terminal moraine at Kingston, 

 which is only midway down the valley. 



As the warmth increased, the glaciers retreated to their 

 present position around the summit of Mt. Earnslaw, leav- 

 ing the valley dammed-up by the moraine at Kingston, and 

 filled by the water formed by the melting of the ice. On 

 the sides of the valley, in many places, huge blocks of stone 

 were scattered, similar to those in the Kingston moraine. 

 The rounded form of roches moutomues was also given to the 

 low hills and -knolls along the shores of the lake. 



Lake Wakatipu thus furnishes a striking example of a 

 lake filling a glacier-worn rock-basin, the lower lip of which 

 has been raised by the formation of the moraine at Kingston. 

 Taking Lake Wakatipu and the ancient lake-basin that con- 

 tinues below it, as one valley, we have an instance of a rock- 

 basin that has been worn out by glacial action to a known 

 depth of 1,400 feet. That this is a true rock-basin is shown 

 by the fact that in the Dome Pass, at the southern end of the 

 old lake, the country rock again comes to the surface in the 

 bottom of the valley. Although the glaciers probably at one 

 time passed beyond this point, yet they left a barrier of rock 

 across the valley, which formed the southern end of the an- 

 cient lake, and compelled the waters to cut a new channel to 

 the S. E., that resulted in the complete drainage of the val- 

 ley. Such we conceive to be a simple, although very im- 

 perfect, reading of the grand history of Lake Wakatipu. 



