204 THE fOORNALNONIGEOLOGY. 
there is a narrow skirting tract of lower ground, a portion of which 
is of moderate slope, and often takes the form of a series of imper- 
fect terraces. These, insome places, appear to be merely develop- 
ments of the talus slope, but in others to constitute remnants of 
a lower plane of erosion, which has a somewhat wide prevalence, 
although not an important feature of the general topography of 
the region. From these lower skirting tracts the ascent to the 
upper plain is usually steep, though rarely strictly precipitous. 
The edge of the plateau is notched by a series of short val- 
leys that lead down from the summit plane. The length of these 
is not usually more than two or three miles, except in the case 
of the greater arms, where, if we include the portion occupied 
by the bays, the length reaches a dozen or even a score miles. 
At the head of the valleys, the descent from the plateau is usually 
at first prompt, while towards the mouths of the valleys the 
gradient becomes lower and is usually determined by the lodg- 
ment of gravelly wash from above. The heads of the larger 
valleys are usually occupied by glaciers. These descend from 
the plateau into the valleys either by cataracts or by steep slopes. 
If the glacial tongues do not extend the full length of the valley, 
as is frequently the case, the lower portion is occupied bya broad 
plain of gravel and bowlders of glacial derivation, which gives a 
free and gentle descent to the glacier in its terminal portion. At 
the junctions of these glacial valleys with the Gulf, there is some- 
times a notable delta, broad and symmetrical, but not very large. 
They do not protrude far into the Gulf even when its waters are 
not deep The most notable of those observed was the one in 
front of the Fan glacier. The beautiful fanning out of the glacier 
at its extremity is reproduced in an almost equally symmetrical 
deployment of its delta. There are several of the valleys, however, 
which, though filled nearly to their mouths with glaciers, have 
no protruding deltas at all. The little embayments at their 
mouths are not yet filled with glacial wash. This is an observa- 
tion worthy of note in its bearings upon the duration and activity 
of the glaciation. The valleys occupied by the Gnome, the 
South Point, and the East glaciers, may be cited as illustrations. 
