88 Kansas Academy of Science. 



sheets in the valleys or as terraces on the hillsides, a phe- 

 nomenon which does not exist. Third, had the till been eroded 

 in the manner supposed above, the erosion must have oc- 

 curred before the deposition of the marine beds; and these 

 beds, in turn, would preserve the beach gravels beneath them 

 from erosion. No such rolled gravels now exist beneath the 

 clays. Fourth, had there been such an erosion of the till, the 

 kames and marine deltas would not have escaped in such a 

 good state of preservation. Fifth, the lenticular sheets of till 

 on the northern slopes of hills must have substantially the 

 same origin as drumlins themselves. Yet there are multitudes 

 of these hillside lenses in regions where no genuine water- 

 washed gravel is to be found. 



Another theory is that drumlins are the remains of a for- 

 mer sheet of till irregularly eroded by the glacier. But it is 

 difficult to see how a glacier can deposit till and not at the 

 same time deposit glacial gravel. 



In speaking of the drumlins of New Hampshire, Emerson 

 says:^ "Could one raise the stratum of stony clay which over- 

 spreads the valleys, as one lifts a plaster mask from the face, 

 it would be found that its under surface had been exactly 

 molded to every line and curve in the rocky substratum; but 

 its upper surface would have the effect of a comic mask, swell- 

 ing with unequal thickness over every prominent feature; dis- 

 torting and concealing its true form, and sending up great 

 protuberances due wholly to a thickening of its own mass and 

 not molded on any projecting ledge below. The protuberances 

 formed thus by local thickening of the sheet appear now as 

 drumlins, massive domed hills, in shape like an inverted canoe, 

 with their long axes pointing in the direction of glacial mo- 

 tion from north to south." 



Hitchcock and Wright have thought drumlins to be, per- 

 haps, the material of terminal moraines swept over and 

 massed in these peculiar forms by subsequent farther ad- 

 vances of the ice-sheet. 



King and Dana have conjectured that drumlins, at least in 

 some cases, were made by superglacial streams, charged with 

 drift, pouring through crevasses or a moulin to the land sur- 

 face, there depositing their drift, which afterwards by the 

 outflow of the ice would be subjected to its pressure and sculp- 

 turing. 



3. Monograph 29, p. 545. 



