414 W. UPHAM ESKER NEAR WINNIPEG, MANITOBA 



high, consisting of sand and gravel on its southern slope, but of till on 

 its top and northern slope, with many boulders up to 5 feet in diameter. 



Till overlying the Esker Gravel and Sand 



The most extraordinary feature of this esker is the envelope of till 

 covering its western quarter, along the course of the great excavation 

 first described, reaching nearly a mile east from Birds Hill Station. In 

 the excursion of the geologists attending the British Association, this 

 overlying till, first observed, as I think, by J. B. Tyrrell, of Toronto, 

 Canada, was clearly seen by all the party, including several British geol- 

 ogists, others from Canada, and, among United States geologists, Frank 

 Leverett and Frank B. Taylor, experts in all phases of glacial, fluvial, 

 and lacustrine action. 



Here I must make a confession and apology. That this most signifi- 

 cant feature of Birds Hill was not observed by me in my former field 

 work, and therefore was not described and delineated in my reports pub- 

 lished in 1890 and 1895, was doubtless due to the thinness of the till 

 sheet and its yellowish gray color, similar to all the esker gravel and 

 sand. 



The section and description given by me in those reports, however, 

 especially mention a mass of till seen inclosed within the esker, of which 

 I wrote: 



"Imbedded In this coarse gravel on the south side of the excavation I noted 

 a mass of ordinary till, unstratified bonlder-clay, inclosing gravel and boulders 

 in a solid matrix of somewhat sandy clay, wholly bounded by definite but 

 irregular outlines, its dimension vertically being about 10 feet and its length 

 20 feet. ... It probably was derived from the drift that was contained 

 within the ice-sheet and finally overspread its surface when the greater part 

 of the thickness of the ice was melted. From a sheet of drift thus deposited 

 on the ice that formed the bank of the glacial river this mass may have fallen 

 into its channel." 



N'o similar inclosed mass of till was seen in the sections examined last 

 summer and autumn; but I believe that the till mass seen in 1887 and 

 thus described was in its original position as imbedded in the esker by 

 falling from above while the gravel ridge was being accumulated, rather 

 than as a part of a talus fallen from the gravel and sand beds and from 

 the overlying till sheet on account of their being undermined by the 

 excavation. 



Boulders occurring in considerable numbers over the northern slope of 

 this part of the esker and left where the gravel and sand had been exca- 

 vated, I endeavored to explain in the former reports as follows : 



