COLUMBIA GLACIER 
75 
of the antecedent condition of the glacier. On the one 
hand, the embayment may have been so full of ice that the 
surface gradient was outward; or, on the other, the glacier 
of the main valley may have had so low a surface that 
there was no tendency to overflow to the comparatively 
shallow side valley. 
The first case implies snow accumulation in the embay¬ 
ment a few decades ago at a rate not since maintained, 
and would correspond to a general expansion of glaciers 
followed in later decades by contraction; but the rela¬ 
tions of the ice to the forest, to be described presently, 
show that such contraction has not taken place. The 
second case implies a general expansion of the glacier as 
the important element of its later history. * 
Another medial moraine of the great ice field north 
of the nunatak passed just east of the nunatak and 
continued down the eastern arm of the glacier to its 
end, where it contributed toward the building of a 
great alluvial delta which was gradually obliterating one 
of the lakes. 
At the western margin of its principal tidal cliff* the 
glacier rested on a bank of drift at the level of low tide, 
and this bank extended eastward as a shoal, on which 
bergs were stranded, for several hundred yards from the 
shore. A bank also extended eastward from the island 
against which the ice front rested, constituting at low 
water a stony cape half a mile long near the foot of the 
ice cliff*. These banks testify to a lingering, or finger¬ 
ings, of the ice front near the position of its modern maxi¬ 
mum, but it is not easy to estimate the duration of the 
fingering. The western bank is built in deep water, 
but may have been constructed rapidly, as the contig¬ 
uous portion of the glacier is heavily charged with drift. 
The eastern bank margins a part of the glacier front 
carrying little debris, but occupies an arm of the bay which 
