36 The A mi ricu a Geologist. July, 1899 
those <>r Kennebunkport, Me. They have the same rose-col- 
ored augite, and the relative amounts and arrangement of the 
several constituents are also about equal. 
The high percentage of silica in dike 3 is exceptional for 
the diabases; it corresponds very closely to the analysis, in 
column V, of the augite porphyrite from Kennebunkport. 
No hvpersthene was found in any of the slides. 
The writer is indebted to professors Kemp and Tan- for 
suggestions, and especially to the former for the use of his 
large collection of slides of the lake Champlain and other 
dikes, which he kindly loaned for study and comparison. 
Geological Department, Cornell University, Ithaca, X. Y. 
ENGLACIAL DRIFT. 
By Warren Vpham, Somerville, Mass. 
Application of the term Englacial Drift. — This term was 
proposed ten years ago by Prof. T. C. Chamberlin for the 
portion of the unstratified glacial drift which was enclosed 
within the ice-sheet at the time of its final recession from any 
area, being named '"''Englacial or Superglacial Till (since the 
material embraced in the ice must have become superficial by 
ablation before it was deposited)."* Previous to that time, 
however, the doctrine that much drift was incorporated in the 
lower part of the ice-sheet, being thence deposited partly as 
unstratified drift, or till, and partly as stratified beds of 
gravel, sand, and clay or fine silt, borne away and laid down 
by the streams which flowed from the melting ice-border, had 
been definitel}' - worked out and published from many obser- 
vations and studies by J. I). I)ana,f N. S. Shaler,J N. H. 
Winchell,§ G. F. Wright, || C. H. Hitchcock,** the present 
*U. S. Geol. Survey, Third An. Rep., for 1881-'82 (pub. 1883), p. 297. 
tTrans., Conn. Acad, of Arts and Sciences, vol. ii, 1870, pp. 06-80. Am. 
Jour. Sci., in, vol. v, pp. 198-211, March, 1873, and numerous papers in 
vols, x, xii, xxiii, xxiv, xxvi, and xxvii, 1875-1881, Manual of Geology, 
first ed., 18(52, p. 517; second (1874) and third (1880) eds., p. 543. 
JProc, Boston Society of Natural History, vol. xiii, 1870, pp. 196 "204. 
U. S. Geol. Survey, Seventh An. Rep., forl885-'86 (pub. 1888), pp. 322, 
323. 
§Geol. and Nat. Hist. Survey of Minn.. First An. Rep., for 1872, p. 62. 
Pop. Sci. Monthly, vol. iii, pp. 293, 294, July, 1873. 
Iproc, Boston Soc. Nat. Hist., vol xix, pp. 47-63, Dec. 1876; vol. xx\ 
pp. 210-220, April, 1879. 
**Geology of New Hampshire, vol. iii, 1878, chapter ii, p. 282, etc 
