Prof, T. C. Chamberlin. 
47 
silt laminations are often seen to do in the case of embedded 
rock masses. This seems to indicate that the embedded bowlders 
do not descend through the ice by virtue of superior gravity, but 
are retained in the original position given them by the embed- 
ding process. The extent to which the basal portion of the ice 
is laminated is quite remarkable. In selected cases as many as 
twenty laminations might be counted to the inch. These lami- 
nae are sometimes very symmetrical, straight and parallel. At 
other times they are undulatory in varying degrees, while in some 
instances they are greatly curved and even contorted in an intri- 
cate fashion. 
HEIGHT OF THE EMBEDDED DEBRIS IN THE 
GLACIAL BASE. In view of opinions that have prevailed to 
some extent relative to the rise of rocky material through a gla- 
cier, it is important to note the heights to which the embedded 
rock was found in the ice, and its behavior at the glacier’s mar- 
gin. The debris-bearing layers are found to be essentially par- 
allel to the base of the glacier. This is very notably true in the 
larger view. Locally the layers rise and fall. Sometimes in the 
presence of obstacles they are thrust very notably upwards, and 
again in the lee of embossments they curve rapidly downwards 
and even in some instances are seen to be 'doubled upon them- 
selves. On the whole, however, the ups and downs nearly bal- 
ance each other, and the rocky material remains confined to the 
lower part of the glacier. In the main, debris is limited to the 
lower 50 or 75 feet. Sometimes the dirty layers prevail up to 
100 feet and rarely beyond. I think that 150 feet might be 
named as a rather extreme limit. Even at the border of the 
glacier the clean, white layer of ice above the debris-bearing 
stratum usually constitutes one-third or more of the section. 
The view that the debris habitually works up to the surface and 
forms a layer upon it as it nears the border of the glacier is 
without support. 
INTRODUCTION OF THE DEBRIS. The question of 
the method of introduction of the debris obviously becomes one 
of prime importance, not only on account of its interest in con- 
nection with the glaciers under study, but because of its appli- 
