Acciinn'lof'on oj Dniml 1 iis. — ('j>Ji((iii. H5i> 
down toward the open land, causino- tiu' deposition of much suh- 
ghieial till ; and whenever a stratum of the englacial drift became 
covered with mucli new ice, it would probablj' be aggregated en- 
glacially or altogether subglacially in drumlins. The drift that 
had been eroded and lifted into the lower part of the ice during 
many centuries might thus be rapidly accumulated in the drumlins 
during only a verj' small fraction of the time that had been required 
for its being stored up in the ice. Through such processes I can 
l)etter understand the origin of these prominent drift hills, than 
by any method that I am al)le to imagine for nearly contempora- 
neous erosion, subglacial transportation, and deposition of their 
till. Moreover, T find great difficulty in forming a conception of 
convergent basal currents powerful enough, in spite of their fric- 
tion on the land, to amass these hills; but the inequalities of con- 
tour of the outer belt of the ice, as irregularly thinned by ablation, 
may well have produced upper and central currents of sufficient 
energy to sweep the englacial drift stratum into irregularly 
grouped and scattered or even solitar}' drumlins. when new ice 
and snowfields added a considerable depth over all the previous 
drift-covered surface of the ice sheet. 
The second objection alluded to arises frcnn the abundance or 
frequency of glaciated stones and boulders in the till of the drum- 
lins and from its compactness, flaky lamination, and other features 
which prove it to l)e subglacial till or ground moraine. If this 
drift was englacial during a considerable time and became massed in 
these hills beneath only a few hundreds of feet of ice, could it pre- 
sent so impressive characteristics of subglacial accumulation under 
heavy pressure? To this question we must reply that the stratum 
of englacial drift would be subjected to much wear of its bould- 
ers and smaller rock fragments as they were carried forward with 
shearing and sliding motion to the drumlin accumulations, and 
that in becoming lodged on the surface of the drumlins or on 
other and low deposits of subglacial till, they would be further 
striated and planed. The previously englacial drift in being so 
transported and deposited would acquii'c all the marks of ice- 
wear which the till of the drumlins exhibits, and the pressure of 
500 to 1,000 feet, more or less, of solid ice flowing downward 
across it would seem adequate to produce its very hard and com- 
pact condition. We are thus able, as T believe, to account for all 
the differences between these deposits and the mostly unworn 
