510 THE JOURNAL OF GEOLOGY. 
formation the “upper” bowlder-clay is characterized by abun- 
dant associated silty beds, and no extensive moraine-like deposits 
are known to be connected with either the “lower” or “upper” 
bowlder-clays. Further eastward, the northern continuation of 
the Missouri Coteau to the North Saskatchewan may indicate 
the limit of the Wisconsin formation. It is at least notable that 
beyond the Céteau a well-marked system of eroded valleys 
exists,’ which finds its limit at the Céteau in a manner much 
resembling that ascribed to the valleys of the Post-lowan 
interval. 
According to the scheme of correlation suggested above, it will 
be observed that the ‘‘western”’ bowlder-clay must represent an 
epoch of glaciation antecedent to the Kansan. There can be but 
little doubt that this corresponds with the time of maximum 
development of the Cordilleran ice-sheet, but as there was at 
least one subsequent epoch of important development of this 
ice-sheet, I would suggest that this stage may be named “ Alber- 
tan.”’ The Albertan ‘‘formation’”’ to comprise both the “ west- 
ern’? bowlder-clay and the derived Saskatchewan gravels. 
We may further, although with some reserve as yet and pro- 
visionally, accept the hypothesis that the Saskatchewan gravels 
are contemporaneous with the Lafayette gravels, and in this case 
the suggestion made by Professor C. H. Hitchcock in a late 
number of the American Geologist? that the Lafayette gravels 
represent in the East a glacial epoch earlier than any of those of 
Professor Chamberlin’s classification (which it must be remem- 
bered is based upon the region of the Laurentide glacier only) 
would be substantiated. The bowlder-clays of this epoch may 
have been obliterated by later events in the East, but still remain 
unchanged along the base of the Rocky Mountains. Professor 
Hitchcock further suggests in the same note that the two periods 
of maximum moisture in the Great Basin may correspond with his 
supposed first epoch of glaciation and the Kansan epoch, a hypoth- 
esis which would correspond very well with that here proposed. 
* Geology and Resources of the Forty-ninth Parallel, p. 230. 
2Vol. XV., p. 330. 
