FIRST WESTERN EXPEDITION 





149 



The most extraordinary feature in this small ice plateau 

 near Knob Head Mountain is that the moraines here lead down 

 into Taylor Glacier. Hence they cut right across the upper 

 portion of glacier above Cavendish Falls, and show that the 

 ice west of the latter is almost wholly flowing into the Dry 

 Valley region and not into the lower Ferrar, as was supposed. 

 This looks as if the " South Arm " and the glacier from the 

 north side of Mount Lister formed the main supply of the 



o 





See 



Plan of the bygone twin glaciers of Lake Luzern, whose overflow led to the 

 break through the high range near Vitznau. A close parallel with the 

 conditions near Knob Head between the Ferrar and Taylor Glaciers. 



Lower Ferrar, while the northern portion (nie Upper Ferrar 

 and Dry Valley) is a distinct glacier now temporarily united 

 with it after the fashion of the Siamese twins. This type of 

 union is by no means unknown, and indeed explains the 

 structure of Lake Luzern — that beautiful high-cragged chain 

 of lake basins in central Switzerland. Here also two inde- 

 pendent glaciers (the Reuss and the Aar) cut out deep parallel 

 gorges as they moved to the north. 



They spread out laterally, and ultimately the Reuss Glacier 

 overflowed to the west, and cut through the high ridge forming 

 the picturesque cliffs of the Rigi and opposite shores. 



