104 Tlie American GeoJogisf. March, 1895 
ioiidfdir I '|i|H'r ( '(i|i|)i'i-lirariii,i;' scries of Logan,* and nui as originally 
proposfd Id inchulc both iiiipcr and lower divisions. 
It Ihus appears that t he term Nipigon, esiiecially as compared with 
Keweenawan (or some lorm ol' this name), has lillle claim as a general 
age designation for the copper-hearing rocks of lake S\iperior. .Moreover, 
it seems eminently fitting that a name derived from Keweenaw point, 
where tlie copper-bearing rock.s occur in typical develoi)ment and whert; 
they have been most carefully studied, should be per])etuated In the 
designalion of this series of strata. Ikit as to whether we call them 
Keweeiiian, Kewenian. Keweenawian or Keweenawan is not very impor- 
tant. However, the last form (Keweenawan) has been more generally 
used than any other, and is the one adoi)ted in the reiiorts of the Wis- 
consin and Tniti'd States (ieological Surveys, antl is used l)y Prof. ('. R. 
Van Hise in his correlation paper on tlie Archeaii and ,\lgonkian.f It 
tluis, on the whole, seems the most appropriate and its use will engen- 
der less confusion than that of any other. T. S. (tRant. 
yiiuneapolis, Feb. Sth, IhV.',. 
Dkumlin Acci'MULATiON. After hearing and seeing Prof. C'hamber- 
lin's e.xceedingiy instructive presentation of his observations and photo- 
gra[)liic views taken in (Greenland, as noted in tlie rejjort, on following 
jiages, of papers at the recent meeting of the (ieological Society, I ha\i' 
tliought that it may be useful to point out the several features(jf drum- 
lins, and ])ortions of my e\i)lanation of their mode of accumulation, 
AYliich receive illustriition in the glaciers of tiie Inglefield (iulf region. 
1. The large amount of englacial drift in these glaciers is all that my 
theory of drumlin formation requires. Professor Chamberlin supposes 
this to be nearly all derived from rock knobs and hills, whence the on- 
tlowing ice sweeps away the drift into its closing currents on the lee 
side. While this must l)e true, if there are such hills, for part of the 
englacial drift, it seems fully jiroved by the Pinnacle hills at Rochester, 
N. v.. by Bird's hill near Winnii)eg, etc..:): that the North American 
ice-sheet on some nearly level areas gathered much drift into its lower 
part by upwardly flowing currents; and such, too, 1 think to have been 
the mode of derivation of the greater part of the (ireenlaud englacial 
drift. 
2. The oval form, moulded (not sculptured) in the process of growth 
of the drnmlins: their accretion of new drift simultaneously o\cr all 
their surface: the lamination of I heir till, now a|>paienlly dvie to this 
gradual accretion rather than to the ice pressure: and I he frequently 
observed downward and uinvard c\ir\ing lamination in the drumlin till 
where it encloses boulders, — all t hese noteworl hy features are well ex- 
hibited by the englacial drift and the little submarginal drumlins seen 
ill l)rocess of formation from it l)enealh the lei'niinal ice-clitfs of these 
glaciers near Bowdoin bay. 
;{. The place, Avith relation to the ici'-sheet. of the formation oi our 
*Report of the Royal Conuiiission on the Mineral Resources of Ontario, pp. 2, 36-39, 
Tovonto, 1890. 
tU. S. Geol. Survey, Bull. No. 86. 1S92. 
^Bulletin, Geol. Society of Aineric:i. vol. v. pp. 71-S4, Jan., iNi)4. 
