306 E. C. ANDREWS. 



This wall also faces the more important tributary stream, 

 namely, the Arthur. Deltas encroach on the head waters 

 of the Sound. The tributary canons retreat on slightly 

 rising grades and are characterised by very high and well 

 aligned walls devoid of spurs, and which dominate wide 

 valley floors. Here also steep cliff slopes pass above into 

 a less steeply inclined series of slopes. The same great 

 quarrying action with the formation of V-shaped bottoms 

 as occur at Yosemite, are noticeable along some of the 

 tributary valleys of Milford. 



Significance, — The wonderful amount of precipitation 

 along this coastal strip 1 coupled with the steep channel 

 slopes and the canon constrictions produced glacial pressures 

 of great strength. At the constriction formed at the 

 Arthur and Oleddau confluence, a basin was formed which 

 retreated up the feeding canons, but without possessing 

 much depth. Lower down stream than the channel con- 

 striction formed by the Arthur and Cleddau confluences, 

 one may observe the influence of the large Harrison 

 Cove tributary [Andrews (a) Fig. 6], and the still more 

 marked constriction associated with the great height of 

 the walls at Mitre and White Peaks. Here then a deep 

 basin was formed, which in time, by headward recession, 

 became connected with the basin at the fiord head. During 

 the recession marked undercutting with the production of 

 Hanging Valleys was effected. The northern wall was 

 especially selected for attack, owing to the set towards it 

 of the stronger glacial motion. Moreover, owing to the 

 inability of the glacier to find relief laterally from its 

 enormous pressure, the basal ice was held to its work of 

 vertical corrasion. Had the fiord walls been but 1,000 feet 

 in height much lateral escape would have ensued, but held 



' The precipitation in this region to-day varies from 150 to 250 inches 

 per annum. 





