BERING SEA 
189 
a highly inclined slate, and the shaping of the surface has 
been wholly by erosion. Except at the coast, the rocks 
are concealed by tundra. This spongy growth obstructs 
the flow of water, so 
that streams are rare; 
but we landed at one 
of these rare streams 
and had a view of its 
valley (fig. 91). The 
valley is evidently 
one of mature de¬ 
velopment, and its 
profiles are perfectly 
adjusted to the associated lines of drainage. The divides 
are broadly rounded, but the rounding is that characteristic 
of inter-stream summits where the vegetal mat is close, 
and is distinctively non-glacial. The bed-rock here has 
the same physical character as that in the Kadiak region, 
but the topographic aspect is altogether different. About 
fig. 90. 
UNGLACIATED KNOB ON ST. MATTHEW 
ISLAND. 
FIG. 91. STREAM-GRADED VALLEY NEAR PORT CLARENCE. 
Kadiak the hills have moutonnee forms, the hills and hol¬ 
lows have a dominant trend, and the drainage is youthful. 
At the Port Clarence locality the topography does not 
