928 THE JOURNAL OF GEOLOGY. 
His observations tallied to such a remarkable extent with the 
results obtained in wax by the author that it has seemed impor- 
tant to consider the resemblance. 
In comparing the two it must be recognized that the basal layer 
of dirty wax represents many débris layers and lamine at the 
bottom of the ice and the lines above higher series of débris layers 
and lamine. The seeming disparity in size of the wax experi- 
ments with the glaciers, need not be the cause of any hesitancy 
in comparing the results. Professor Chamberlin places the maximum 
limit of dirty ice at 150 feet of the basal part and thinks that it 
is “chiefly confined to the lower fifty or seventy-five feet.” 
The experiments were supposed to represent only the basal por- 
tions of the ice and a 7% inch escarpment in a layer 6 inches 
thick is strictly comparable to an obstruction 10 to 20 feet high 
in 50 or 100 feet of the basal part of the ice. 
In regard to the passage of the ice over low prominences, he 
says, p. 205, ‘‘In meeting obstacles in front, the basal beds have 
the habit of curving upward, carrying the débris with them.” 
Again, p. 208, ‘‘ Behavior of Ice in passing over low Prominences: 
Several excellent opportunities for observing the behavior of ice 
in passing over low embossments were offered. From the front 
of the embossment there originated laminz which extended 
backwards with a graceful, arching curve, much like the profile 
of a drumlin. A portion of the ice remained between these 
curving laminations and the upper and rear portions of the 
embossment. After reaching a point in the rear of the emboss- 
ment, the lamine curved downward with increasing rapidity until 
well in the lee, when they turned about with a more or less sharp 
curve, or even angle, and ran backward to some point not far in 
the rear of the embossment, where they ended. The higher 
laminee made the longest curves and had the sharpest angles in 
the lee of the embossment. It appears obvious that the ice in 
the lee of the embossment moved more slowly than that above; 
hence the doubling of the lamine upon themselves. It appeared 
upon close inspection that some of the inthrust layers described 
above consisted in reality of very sharply reduplicated lamine. 
