GE OAD) 2 EXO SIMES NOLS OO LMT SUTIN AEB ER LA 509 
now been confirmed, and it follows from it and from the inferior 
position of the Saskatchewan gravels to all the previously recog- 
nized glacial deposits of the plains, that we have in this region 
no less than three bowlder-clays to reckon with. The earliest of 
these is derived entirely from the Rocky Mountains and does 
not, as a bowlder-clay, extend very far from them. The two 
later bowlder-clays contain stones of mixed eastern and western 
origin, each variety preponderating in the direction of its origin. 
A general section of the drift deposits of the region, as now 
“understood, thus shows, in descending order: 
1. Silts, sands and gravels. 
2. ‘“‘Upper” bowlder-clay. 
3. Inter-glacial deposits. 
4. “Lower” bowlder-clay. 
5. Saskatchewan gravels derived from “western” bowlder- 
clay. 
It is not quite certain to which of these deposits the high-level 
terraces and shingles correspond, but it appears probable that they 
may be assigned to the time of the ‘“‘upper’’ bowlder-clay or to 
that of its close. Neither is it yet definitely known whether the 
“lower’’ or “upper”? bowlder-clay of the plains extends furthest 
in toward the base of the mountains. In the absence of the 
inter-glacial beds, no satisfactory means of distinguishing these 
deposits in isolated exposures has been found. 
It is hoped shortly to publish in sufficient detail the obser- 
vations upon which these preliminary statements depend; but 
without entering at all into the question of the mode of origin 
of the several deposits, it may be of interest here to note their 
possible relation to those of the glacial epochs or stages 
recently classified by Professor T.C. Chamberlin. The ‘lower’ 
bowlder-clay of the plains of western Alberta, may I believe be 
pretty certainly correlated with his first or Kansan formation, in 
which case the inter-glacial deposits of the Belly River would 
represent the Post-Kansan interval and the ‘upper’ bowlder- 
clay of the same region the Iowan formation. Like the Iowan 
