310 Transactions. 



(2.) Glacial Cirques. 



By far the finest example of a glacial cirque is to be found at the head 

 of the U-shaped portion of Park Valley. This cirque is nearly half a mile 

 across, and is bounded by mural precipices of imposing appearance. At 

 the heads of the other U-shaped valleys the cirques are not so typically 

 developed, the precipices being inconspicuous or absent. 



(3.) Rock Basins. 



There is every reason to believe that a rock basin exists in the floor 

 of the cirque at the head of Park 'Valley. Since the disappearance of the 

 ice it has been filled in with alluvium, and therefore its existence can only 

 be demonstrated by evidence supplied by the general topography of the 

 valley-floor. This evidence will be set forth below (p. 314). 



(4.) Glacial Hanging Valleys. 



Three glacial hanging valleys open into the cirque at the head of Park 

 Valley. They lie at heights of from 360 ft. to 510 ft. above the surface 

 of the alluvial flat forming the present floor of the cirque. The largest 

 has a length of about 15 chains, and the other two, which lie close together 

 and are only divided by a low rocky ridge, are about 6 chains and 8 chains 

 in length respectively. The lips of all three glacial hanging valleys have 

 been cut by the streams that have drained the latter since the disappear- 

 ance of the ice. 



The floors of the glacial hanging valleys of Park Valley, and particularly 

 that of the largest — and the evidence is therefore the more conclusive — 

 show some signs of downward curving at the points where these valleys 

 terminate and open into the main cirque. For this reason it is clear that 

 the ice in the U-shaped hanging valleys must have descended to the head 

 of the main glacier as icefalls ; the upper surface of the ice in the main 

 cirque — i.e., the head of the trunk glacier — must therefore have stood 

 somewhat below the level of the floors of the U-shaped hanging valleys, 

 and probably attained a thickness of 500 ft. If the surface of the ice 

 forming the head of the trunk glacier had stood above the level of, or even 

 on a level with, the floors of the U-shaped hanging valleys, the terminal 

 downward curving of their floors would have been absent, and the tribu- 

 tary glaciers would have joined the main one at grade. This they may 

 have done during the maximum phase of glaciation, the icefalls and the 

 wearing of the lips of the glacial hanging valleys by them being referable 

 to a later date. 



Glacial (U-shaped) hanging valleys occur at the heads of some of the 

 other glaciated valleys also. There is a tiny one at the head of the valley 

 of Bennington Creek. The cleft cut in its lip is in its incipient stages, so 

 that small waterfalls still descend into the main valley. The precipices 

 of the Mitre Peak surmount the north-east side of this hanging valley, 

 and its head lies in the side of the main watershed of the Mitre-Holdsworth 

 Range. 



Another small glacial hanging valley is situated at the head of the 

 glaciated portion of the Mangaterera Valley. Its lip also has been cut by 

 the small stream which now drains it. 



