No. 5.] SPENCER — SURFACE GEOLOGY. 289 



runninir water, hurlinir alonii; the dehrls from the meltinu iilacier. 

 Again glaciers derive their principal loads of debris from over- 

 liangiug rocks, which would seldom appear above a grand conti- 

 nental glacier. Ice with even little or no foreign material may 

 polish surfjices (not scorify) when hurled by the action of waves 

 and tide, as seen by Prof. H. Y. Hind, on the coast of Labrador, 

 where the hard rocks have been polished for several hundred feet 

 above tide, durinir the time that that portion of the continent has 

 been risins:. 



From various x\rctic expeditions, we learn about the enormous 

 quantity of detritus which is annually removed by the floe or 

 coast ice, though only half a dozen feet thick. This ice gets piled 

 up, and by the action of wind and tide abrades the shore to an 

 elevation of 30 feet or more. 



Our American ueoloi'ists of the ulncial school seem unwillimr 

 to attribute the scorifying power to floating ice, which becomes 

 temporarily stranded. Even the grindiuir of the contained stones 

 in floating ice stranded at low tide, in the trough of waves of 

 a rough sea, acting during long periods of time, would produce 

 great cflccts. Fairly considering the question, the ice-marked 

 surfices of the region of our study tell us but little in favor of 

 either the glacier or the iceberg hypothesis. Even the south- 

 eastern striations in the highland counties of Ontario (character- 

 ized in part by the Artemesia gravel) at most could only have 

 been produced by local glaciers discharging small bergs into the 

 Ontario sea, whose general currents were drifting to the south- 

 westward. 



Any continental glacier passing ov^er the region of our study 

 must have filled the basin of the western end of Lake Ontario and 

 the ancient Dundas valley (more than two miles wide, and from 

 750 to 1000 feet deep) else the Niagara escarpment of preglacial 

 date facing the lake would have been planed ofi" by the eroding 

 force which struck it obliquely without having the direction of 

 the force changed (except in the valley itself) for we find the 

 summit angles sharp. Nor has this sharpness been subsequently 

 produced by frost action as indicated by the talus at the base of 

 the slopes. The ancient Dundas valley, as has been pointed out, 

 brings additional proof, that the region was not excavated by 

 glacial action. Even the removal of the upper hundred feet of 

 the escarpment on the western side of Glen Spencer, which most 

 nearly resembles glacial action, was not cficcted by ice-action but 

 Vol. X. s 2 No. 5. 



