TILL OVERLYING THE ESKER GRAVEL 417 



deep, is good gravel and sand. Its coarser layers commonly have pebbles 

 3 to 5 inches in diameter, with no larger stones nor boulders and no till. 

 Some layers are chiefly sand, with scanty gravel, and rarely a bed 1 to 2 

 feet thick and 50 to 75 feet long is almost clear sand. 



Returning to the west end of this long excavation, near Birds Hill 

 Station, and examining the section along its lower northern side, we have 

 for a distance of about 2,000 feet a continuous mantle of till, 6 to 10 feet 

 thick, mostly typical unmodified glacial drift, with frequent boulders in 

 and upon it, but in some parts showing modification, as slight stratifica- 

 tion and assorting by water action. The till and boulders make the sur- 

 face, or through perhaps half of this distance are thinly covered by a 

 I oarsG surface gravel, 1 to 3 feet thick. Beneath the till the esker gravel, 

 excavated continuously for a thickness of 10 to 15 feet and reaching 

 lower, has usually pebbles from 1 to 3 inches in diameter, and in some 

 parts up to 6 inches, all water-worn, with no larger stones nor boulders. 

 It is nearly levelly bedded, but frequently dips 5 to 10 degrees to the east. 



The till terminates at the east end of the part thus noted, there being 

 the surface and 8 feet thick, by an abrupt ascent of its lower boundary 

 at an angle of 70 degrees with the horizon, and is succeeded by fine 

 gravel, which immediately to the east forms all the section, exposed to a 

 depth of 20 feet. 



Within about 50 feet onward the till begins again, and it soon thickens 

 to 6 or 8 feet, its lower boundary being inclined at first 15 to 20 degrees. 

 When it has thus attained a depth of about 8 feet, it runs as a surface 

 deposit 6 to 10 feet thick, or in large part is covered by 1 to 3 feet of 

 coarse gravel, for nearly 1,000 feet. It is underlain, as westward, by fine 

 gravel and sand, excavated to the thickness of about 15 feet, nearly 

 levelly stratified. This stretch of the till envelope ends somewhat like 

 the preceding, but less suddenly, tapering out from a depth of 10 feet by 

 the ascent of its under edge to the surface at an angle of 25 degrees. 



After a second interval of only 50 feet, in which the fine esker gravel 

 comes to the surface, the coating of till is renewed and has a depth of 5 

 to 10 feet at the surface, or with a few feet of coarse gravel over it, as 

 before, for the next 500 feet, curving to the southeast and south. It ter- 

 minates near the end of the excavation, where in the Winnipeg City pit 

 the whole section is again fine gravel and sand, excavated 50 feet in 

 depth from the surface at the crest of the esker. 



Formation of the Esker by a Glacial Etver 



Independently of each other and near together in time, the origin of 

 o^^kers and kames through deposition by ice-walled rivers, small or large. 



I 



