no 



POPULAR SCIENCE MONTHLY 



all the time required for the deepening and broadening of the main 

 trough, the lateral stream was scarcely able to even scratch the lip of 

 the hanging valley (Fig. 4). This point may be illustrated by a 

 specific case, taken not from the Inside Passage, but from Nunatak 

 Fiord, a branch of the Yakutat Bay Inlet which lies about midway 

 between Sitka and Controller Bay just southeast of Mount St. Elias. 

 This fiord has been so recently occupied by ice that vegetation, 

 excepting scattered annual plants, has not yet been able to take hold 

 on the soil. The Nunatak Glacier (Fig. II) has receded up this fiord 

 more than a mile in ten years. Unquestionably there has been power- 

 ful glacial erosion here, for the walls of the fiord are smoothed and 

 grooved by glacial grinding, and there are no valley spurs left. Several 

 of the valleys tributary to the fiord are hanging high above it (Figs. 6 



Fig. 10. Looking Across the Mouth of Disenchantment Bay, Russell Valley (Fig. 11) 

 on Left. This valley is hanging at about sea level. A small valley to the right of this hangs 

 fully 1.000 feet above sea level. A somewhat larger valley ■ n the extreme right of the picture 

 is hanging at a level intermediate between these two. To account for such discordance by 

 faulting would demand very complex block faulting. But the rock walls of the fiord are 

 plainly exposed and there is no evidence of it. Photograph by O. von Engeln. 



and 7), and in all the larger of these small glaciers are still present. 

 The entire absence of forest exposes the conditions here far more clearly 

 than is the case along the forest-clothed Inside Passage. 



Viewed from the fiord, the hanging valley selected for this illus- 

 tration is plainly seen to be a broad, U-shaped trough heading well 

 back in the mountains and with a small glacier at its head. Tbe 

 wide open mouth of this broad valley is truncated by the straight, steep 

 rock wall of Nunatak Fiord and left perched high above even its water 



