114 The American Geologist. February, i8?8 
vania, pointed out the probability that the Monongahela and 
upper Oliio had formerly been reversed and drained into the 
Erie valley. * This hypothesis was afterward amplified by Dr. 
P. Max Foshay,f disputed by Prof. I. C. White; modified and 
confirmed by Mr. F. Leverett,! and finally, with some modi- 
fications, reconfirmed by Prof. I. C. White.§ In order to 
test the validity of his objections to the hypothesis of glacial 
excavation, the writer visited Switzerland and Norway for 
the purpose of personally observing- the mechanical effects 
of modern glaciers, with the result that he saw in them only 
the agents of abrasion — the ice moulding itself round obstruc- 
tions, or smoothing off irregularities, and not ploughing out 
channels. | Indeed, in a more recent visit to Norway, it be- 
came apparent that the great glacial valleys still preserve 
many base levels of erosion — the doctrine of which has not 
been applied to them, and consequently their history is as 
yet unwritten. The extreme views concerning glacial ero- 
sion, held a decade ago, are now greatly modified and do not 
belong to the present dav. 
In 1882, fragments of great beaches, and others which 
were delta deposits, were described as occurring about the 
western end of lake Ontario at various elevations from 500 feet 
above the lake down to its present level. *^' Other fragmeuts 
of beaches had been known for many decades, the most nota- 
ble of which were the ridge roads of New York state, that 
Prof. James Hall, as early as 1842, found to be rising gently 
upon proceeding eastward;** and the same was found to be 
true at the eastern end of lake Ontario. About this time 
Prof. Gilbert was studving the beaches of the western lakes, 
and Mr. Warren Upham those of the Winnipeg basin. The 
*On the ancient upper course of the Ohio river emptying into lake 
Erie. Proc. Am. Phil. Soc, Phil., vol. XIX, 1881. 
tPreglacial Drainage and recent Geological History of western 
Pennsylvania. Am. Jour. Sci., vol. XL, 1890, pp. 397-403. 
jPleistocene fluvial plains of western Pennsylvania. Am. lour. 
Sci., vol. XLII, 1891. pp. 200-212; and Further studies of the Upper 
Ohio basin. Am. Jour. Sci., vol. XLVII, 1894, pp. 247-283. 
§ American Geologist, vol. XVIII, 1896, pp. 368-379. 
II The erosive power of glaciers as seen in Norway. Geol. Mag.. 
Lond., Dec. iii, vol. IV, 1887, pp. 167-173. 
T[ Surface Geology abovit the region of the western end of lake On- 
tario, cited before. 
** Geology of New York. Vol. IV, 1843, p. 35i- 
