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reference is made to the excavating power of glaciers ; but, while acknowledging 

 their efficiency in this respect, the lake basins and sounds of the West Coast 

 are referred to subsidence of the earth's crust. He states : — " This subsidence 

 has been most rapid in the central and western part of the range, so that in 

 the case of a long valley, like that occupied by the Wakatipu Lake, the slope 

 bacame gradually reversed, and what was at fii-st the higher part of a glacier- 

 excavated valley, has become a depression without an outlet." 



The meaning of this seems to be that the depression was subsequent to 

 the glacial excavation of the valley. To realize the condition of the valley at 

 the close of the glacier action, it will be necessary to conceive the bottom of 

 the lake basin lifted up, so that the valley would throughout its entii-e 

 length slope in the one direction. Applying this to the Wanaka Lake, the 

 bottom at the south end would come near the present level of the lake surface, 

 974 feet. The height of the saddle at the head of the Makarora Valley is 

 given by Dr. Haast at 1716 feet, and the distance between the two points is 

 about fifty miles. The fall is therefore 742 feet, or say 800 feet, or a mean 

 slope of 16 feet per mile. But the slope Avould not be uniform, and so be less 

 over a part of the valley. Forbes states that the slope of the glaciers in the 

 Alps is seldom or never under 3 degrees, or 276 feet per mile. He says, 

 however, that the glaciers which transported the blocks of gTanite from 

 Mont Blanc to the slopes of Jura would not have had a greater mean slope 

 than 1-8 degrees, or 104 feet per mile, and the slope of a great part of its course 

 must have been much less. Reasoning from the semi-fluid nature of a glacier, 

 he does not pretend to fix the limit of mean slope, and he says it might even 

 be as little as 15 min., or 23 feet per mile. From this it will appear that we 

 cannot assume that a glacier would not move with a mean slope so gentle as 

 even 16 feet per mile. But if we are to accept the subsidence theory, it will 

 be legitimate io apply it in such a manner as will best dispose of the objections' 

 that may be urged against it. If we, therefore, conceive the subsidence to 

 have taken place before, and not after, the glacial period, the mean slope of 

 the Wanaka glacier would be greatly increased, and so be brought nearer the 

 ascertained facts of glacier motion. 



When the great glaciers occupied the valleys and lake beds, the climate 

 must have been much colder than it is at pi-esent. The causes of change may 

 have been various. When we contemplate the vast accumulations of denuded 

 material which is now in the valleys, it is evident that the mountains must 

 have been more massive and probably higher before the denudation began. 

 There would therefore be more surface above the snow line, and by the same 

 proportion, greater snow fields and greater cold. But this is inadequate to the 



adopts the arguments and conclusions of the paper cited, but without fully appre- 

 ciating their bearing on the question. — Ed. 



