294 The A?nerica?i Geologist, May, 19001 
BASINS DUE TO UNMELTED ICE MASSES. 
Some parts of the wider channels and low areas inclosed 
among the high plain deposits may mark places where rem- 
nants of the departing ice prevented deposition; and occasional 
bowl-like hollows, not filled by water, doubtless belong in this 
class, while others were caused, as in the course of the Powder 
Horn channel, by gullying action of a torrent. All the large 
lakes of the city area, since they are partly or entirely inclosed 
by modified drift, which forms usually steep banks, rising 10 
to 30 feet above the lake surface, must be attributed to ice 
masses left where the lakes now exist and continuing unmelted 
long enough to allow the adjoining gravel and sand plains to 
be deposited. 
COMPARISON WITH PLAINS OF CAFE COD. 
The conditions of fiuvial deposition forming these sloping 
plains of gravel and sand, with some well defined large water 
courses, other channels of varying depth and width quite un- 
like ordinary stream beds, and small and large inclosed hol- 
lows, holding bogs, ponds, and lakes, are paralleled or nearly 
duplicated at many other localities, in front of our great trans- 
continental moraine belts. Nowhere else, how'ever, are al! 
these features of frontal plains better displayed than on the 
southern part of the peninsula of Cape Cod, the earliest of 
such areas in this country to be studied and described.* 
ESKER KiDGES AND HiLLS. 
Along two courses the Minneapolis plains are diversified 
by protrusion of hilly and ridged deposits of coarser gravel 
and sand. Neither course presents a typical esker, a pro- 
longed ridge, with steep sides and narrowly arched top of vary- 
ing height; but yet each seems to me clearly referable to this 
class of drift formations. They run in the direction of the 
glacial recession, instead of being parallel with the receding ice 
*The Fonnation of Cape Cod, Am. Naturalist, vol. xiif, pp. 489-502, 
552-565, Aug. and Sept., 1879. Also compare Prof. N. S. Shaler's paper. 
Geology of the Cape Cod District, U. S. Geol. Survey, Eighteenth An- 
nual Rep., for 1896-97, pp. 497-593, with plates xcvii-civ, and figures 86- 
92 in the text; and my review of that paper, Am. Geologist, vol. xxiv, 
pp. 79-92, Aug., 1899. 
