Prof. T. C. Chamberlin. 
51 
the greater part made up of coarse granules of ice intimately in- 
terlocked. When these begin to undergo disintegration, the 
granules commence to separate from each other and the struc- 
ture declares itself. Now in these fallen blocks it was observed 
that definite planes of parting were developed between some of 
the layers, while intermediate between these partings the inter- 
locked granules held the crumbling mass together even after 
decay had made considerable progress. These partings were 
sometimes observed even when the layers were not separated by 
any earthy filament, the ice on both sides being white and pure. 
The plane of parting between the layers was often slightly gap- 
ing at the surface of the block, giving the impression that the two 
layers were peeling apart, though the effect was probably due in 
reality to superior melting along the junction plane. I found it 
easy by a moderate stroke of the spike of my alpenstock to split 
the blocks along these partings. The separated faces were 
smooth and strongly suggested an analogy to slicensides. That 
there had been motion of the one layer upon the other seemed 
practically beyond question. Between these partings the ice was 
so far bound together by the interlocking granules that an at- 
tempt to cleave the mass resulted in a fracture of the most 
ragged and irregular sort. 
When we combine these evidences with what has already been 
stated regarding the intrusion and interstratification of the earthy 
material (and the inferences which this interstratification force 
upon us cannot lightly be escaped), it seems scarcely less than 
demonstrated that the glaciers move, in some notable part at least, 
by the sliding of one layer upon another. The bearing which 
this has upon fundamental theories respecting glacial movement 
is beyond the province of this report, but is obviously impor- 
tant. 
RELATION OF THE GLACIERS TO THEIR DEBRIS. 
The northern glaciers afford little that is new respecting lateral 
and medial moraines and they may be neglected. It has already 
been seen that much basal material is carried in the lower layers 
of the ice. It was also a matter of frequent observation that 
debris lies under the ice. Apparently the ice sometimes pushes 
