208 
ALASKA GLACIERS 
cation can be traced across the view. It really includes 
the foreground, at least down to the mantle of moraine; 
and it is part of the wall of the glacier trough, wrought by 
the ice into curves of large radius. But the detail of this 
erosion plane, shown in the center of the field, is distinctly 
hackly, as though (and probably because) the degrada¬ 
tion of the stratified rock was accomplished largely by the 
breaking away of blocks. The prominent angles and 
edges of strata are abraded and highly polished on their 
stoss sides, but their lee facets are unworn. 
The lower view shows the stoss side of a granite knob, 
also near Muir Glacier. Here the indications of abrasion 
are most conspicuous, but a groin crossing the foreground, 
and a niche at the right, are probably remnants of scars 
made by plucking. 
The rock areas best showing the character of the sculp¬ 
ture due to plucking are in the barren regions about the 
glaciers, and these were often included in our views of 
glaciers; but the photographic methods employed to show 
details of the white ice do not secure the details of dark 
rocks. The peculiar embossment topography is merely 
suggested in some cases by the pattern which results from 
the preservation of snow in concavities of the surface. 
See the mountain spur beyond Reid Glacier in figure 14 
and the hill at the left of Hugh Miller Glacier in plate 111. 
Similar patterns appear on both sides of Serpentine Glacier, 
in the photogravure at page 124 of volume 1. 
Figure 102 contrasts several types of sculpture. A tract 
bordering the water of the fiord at the right shows elab¬ 
orate fluting on a grand scale, the abrasive work of a 
powerful, and doubtless fast-moving, ice stream, flowing 
from left to right through the fiord. The material here 
sculptured is argillaceous slate, similar to that at Kadiak 
(figs. 86 and 87). The spurs beyond are partly of more 
obdurate material, including schists and granitoid rocks; 
