18S1.] U'JO [Spenoer. 



linger, as the lower lake region was being desiccated, and therefore we do 

 not find continuous shore lines between many of the beaches ; Carll ex- 

 plains this by the waters being frequently lowered by debacles, apparently 

 an adequate reason. 



Niagara Biver. That the Niagara river is Postglacial, at least from the 

 Whirlpool to Queenston, is apparent. It is known that the Niagara river 

 formerly left its present course near the Whirlpool and flowed down the 

 valley of St. David, which is now filled with drift. This valley (through 

 the limestone escarpment) is not so great as the present canon. This buried 

 valley of St. David could only have been produced after the closing of the 

 Dundas valley outlet of the Erie basin, for until then the waters flowed at 

 a very much lower level. Therefore, it seems necessary to regard this 

 channel (not of very great magnitude) as an interglacial outlet for Lake 

 Erie. 



The geologists of the Western States point to the Forrest bed as a period 

 of high elevation, preceded by the Erie clay (stratified) and succeeded by 

 the yellow stratified clays or loam, corresponding to the Brown Sangeen 

 clay of Canada, which is unconformable to the underlying Erie clays (or 

 Boulder clay in the upper portion of the Dundas valley). So, for the 

 present, we look upon the old course of the Niagara river as the chan- 

 nel excavated during this warm interglacial period. 



Hypotlietical Glacier Origin of the Lakes. The writer, having pur- 

 posely left the hypothesis that the lakes were excavated by glaciers until 

 now, will briefly examine what evidence is existing. One cannot do better 

 than give a summary of what Prof. Whitney (in Climatic Changes) says 

 with regard to the erosive power of ice. " Ice per se has no erosive power. ' ' 

 Glaciers are not frozen to their beds. Ice permeated with water acts as a 

 flexible body and can flow accordingly. In neither the extinct glacier 

 regions of California nor in the shrunken glaciers of the Alps will it be 

 found that ice scoops out channels with vertical sides as water does. 



"No change of form can be observed at the former line of ice. Aside 

 from the morainic accumulations, there is nothing to pijpve the former 

 existence of the glacier, except the smooth, polished or rounded surfaces 

 of the rocks, which have no more to do with the general outline of the 

 cross-section of the valley than the marks of the cabinet-maker's sandpaper 

 have to do with the shape and size of the article of furniture whose face he 

 has gone over with that material." 



The most important work of a glacier is the scratching and grooving of 

 surfaces. This may, however, be done by dry rubbing, and therefore 

 isolated scratched stones or patclies are no evidence. The underlying rock 

 surfaces may lose their sharpness, owing to contained detritus in the ice, 

 and become rounded. The ground moraine is neither characteristic nor 

 important. There is but little detrital material beneath Alpine glaciers, 

 and this is the result of water more than ice. The only characteristics of 

 ice action are striation and polishing. All floating ice shod with stones 

 frozen in them will scratch surfaces over which they rub. The only gla- 



