Hogg.— On some Glaciated Stones from Queenstoivn. 429 



excavation took place. The limestone was cut through, and 

 then the subjacent rocks, until a well-defined valley once more 

 existed. Then came the great Glacier age, and down this valley 

 moved a glacier formed by the junction of glaciers from the 

 Rees and Dart. This glacier continued the work of excavation 

 started by the ancient river. It is, of course, difficult to appor- 

 tion to the river and the glacier the amount of excavation due 

 to each. By some geologists it is held that while glaciers have 

 considerable powers of abrasion they have little or no powers of 

 excavation. The present bottom of Lake Wakatipu is between 

 300 ft. and 400 ft. below the sea-level, and if the main work of 

 excavation was done by the river it is of course necessary to 

 postulate that the bed of the river was considerably more than 

 300 ft. higher than the deepest part of the present bottom of the 

 lake, as a large amount of filling-in may have taken place since 

 the ice-front retreated and Lake Wakatipu was formed. 



The existence of the sounds on the west coast of New Zealand 

 seems to point to a widespread submergence of this region, as 

 there is little reason to doubt that these arms of the sea were 

 originally valleys eroded first by water and then by ice-action. 

 On the other hand, if the excavation has been for the most part 

 performed by a glacier, it is extremely difficult to explain away 

 the marked absence of the graving-tools by which such excava- 

 tion was done. The rock debris by which the bed of the glacier 

 had been worn deeper and deeper would itself present evidence 

 of the grinding and eroding processes in which it had taken part, 

 and rounded, smoothed, and striated stones and boulders should 

 exist in an abundance somewhat proportional to the erosion 

 which had been effected through them. 



Leaving this debatable point, we know that the glacier must 

 have filled the lake-basin to a height slightly greater than the 

 present level of the water. The main glacier was, in the opinion of 

 Captain Hutton, joined at Frankton by the confluent glaciers 

 of the valleys of the Arrow and Shotover, and the united ice-mass 

 moved south to Kingston, where an extensive terminal moraine 

 marks the stopping-place of the ice-front. During a long period 

 of time accumulations of ice-borne debris must have been dumped 

 here, filling the valley and finally erecting across it the dam 

 which now blocks up the south end of the lake. Against this 

 dam. and along the valley-bottom near and for some distance 

 north of Kingston, the retreating glacier must have continued 

 to deposit its burden of fine and coarse material. With the 

 retreat and melting of the ice began the formation of Lake 

 W T akatipu. The waters accumulated, and, their overflow escap- 

 ing by the lowest available point, the River Kawarau came into 

 existence. The presence of terraces at various points along the 



