Englacial Drift. — Upham. 37 
writer,* and doubtless others in this country, and by Otto 
Torellf and N. 0. Hoist}; in Sweden, besides perhaps other 
European writers. Among these Prof. Dana and Dr. Torell 
have given this subject very thorough attention; and the 
writings of the former in the American Journal of Science. 
with the work of Prof. James Geikie on the Great lee Age, 
were the chief sources of my first interest in the problems of 
the glacial and modified drift. This doctrine, so well stated 
by Dana in the papers cited, I have found applicable and an 
indispensable key for the discovery of the origin of the drift 
in New Hampshire and other parts of New England, also in 
New York, and in Minnesota and other parts of the North- 
west, as also in Manitoba. The term englacial in distinction 
from subglacial drift is much needed in the theoretic consid- 
eration of the methods of formation of the various drift 
deposits, and at present attracts special notice from the dif- 
ference of opinion among glacialists as to the probable pro- 
portion of the drift which was englacial when the ice melted 
away. Professors Chamberlinjj and James Geikie || think that 
this englacial drift was of small amount ; but the other authors 
before mentioned think that its amount was large, yielding 
usually an observable superficial stratum of the till and nearly 
all of the modified drift. Prof. R. D. Salisbury** would restrict 
the term englacial to the drift, chiefly boulders, enclosed at 
considerable hights in the ice-sheet and borne along without in- 
termingling with the more plentiful drift held in its basal part; 
but since both these portions of the drift were englacial and 
finally superglacial by ablation of the ice, it seems preferable 
to speak of them respectively ;is the upper and lower portions 
of the englacial drift. 
*Proc., A. A.A.S., vol. xxv, for 1876, pp. 216-225. Geol. of N. H., 
vol. iii, pp. 3-19, 176, 285-309. 
tAm. Jour. Sci., in, vol. xiii, pp. 76-79, Jan., 1877. 
JPaper on the Origin of Eskers, published in Sweden in 1876, re- 
viewed with notices of Hoist's observations of englacial drift in Green- 
land, by Dr. Josua Lindahl in Am. Naturalist, vol. xxii, July and Aug., 
1888. 
^Bulletin, Geol. Soc. of America, vol. i, 1890, pp. 27-31. Journal of 
Geology, vol. i, pp. 47-60, Jan.-Feb., 1893. 
||Great Ice Age, sec. ed., 1877, pp. 415, 416, etc. 
**Geol. Survey of New Jersey, An. Rep. for 1891, pp. 65-83. Am. Geol- 
ogist, vol. x, p. 219; vol. xi, p. 243. 
