462 W. Upham—Northern part of the Connecticut Valley 
The glacial rivers which we have described appear to have 
flowed in channels upon the surface of the ice-sheet; and the 
formation of the kames took place at or near their mouths, ex- 
tending along the valleys as fast as the ice-front retreated. 
Large ‘angular boulders are sometimes, but not frequently, 
found in the kames or upon their surface. They appear to 
have been transported by floating ice. Their rare occurrence 
forbids the supposition that these deposits were formed in chan- 
nels beneath the ice-sheet, from which many such blocks must 
have fallen upon the kames. 
he necessity of referring the formation of these gravel 
ridges to glacial rivers became apparent emaee the exploration 
and study of our a ties in 1875; and in August, 1876, 
this was announced in a “On the origin of Kames or 
Eskers in New Heap In this essay it was supposed 
that these rivers more commonly had their course beneath the 
ice-sheet, but subsequent examination of the underlying till 
shows that this was seldom the case, and that the kames were 
deposited in channels formed on the surface of the ice. Prof. 
Otto Torell, of Sweden,t had pointed out a division of the till 
into two members, the lower characterized by its blue color, 
two or three feet, as is mo ost © ommon, to fifteen or twenty feet, 
- between the upper and Sexe till. It should be added that the 
lower till in a majority of cases has no distinct blue tint, but is 
dark gray; being always somewhat darker than the upper till, 
which is colored by ferric oxide. The lower till may be dis- 
tinguished by an imperfect cleavage in planes parallel to the 
surface, noticeable wherever an excavation has been for a short 
time exposed to the weather. Before this, Professor James D. 
na had insisted that. the deposition of a great part of the 
til took place in the Champlain period, being dropped from the 
“melting ice-sheet. This suggested the origin of the upper till, 
and an explanation of its difference from the lower till ; the 
latter being the ground-moraine, while the former appears to 
ave been satitéslad contained in the body of the ice-sheet, and 
allowed to fall loosely on the surface when this melted. As 
the kames overlie both members of the till, exe plainly were 
deposited in superficial ice-channels.t 
* Proceedings of the American Association for the Advancement of Science, 
vol. xxv 
See this Journal, III, xiii, 
Similar conclusions Tespoding ‘the eke of the kames had os neat - 
other observers, b unknown to me when my views were 
August, 1876. Probably rte first of els was — rN. H. Winchell, State 
