6 ROYAL SOCIETY OF CANADA 



it still carried with the mucli inore abundant Rocky Mountain quartzites 

 and limestones which it found at hand. Here and there a harder ledge 

 of Cretaceous sandstone provided a few large blocks for the mixture. 



How much farther east the Cordilleran ice sheet extended my ob- 

 servations have not determined ; but probably for many miles, since the 

 upper boulder clay is so highly charged with its stones. Search along 

 the cut banks of Bow river below Calgary may settle this point later. 



The Elbow river section just described explains satisfactorily the 

 apparent transition of the Keewatin till into the Cordilleran till; since 

 the latter till was manufactured largely from the earlier till as the 

 Keewatin ice sheet approached its western margin. 



Boulder Clays at other Points. 



Beyond Calgary, as reported by Dawson and McConnell and con- 

 firmed by my own W|ork, only blocks of the underlying sandstone and of 

 Rocky Mountain stones are found in the boulder clay and also in the 

 river gravels, so that apparently the Keewatin ice sheet extended no 

 farther west.^ 



To the south, however, near the international boundary, Archaean 

 boulders are found in the foothills within a few miles of the foot of the 

 mountains and at levels of 4,200 and even 5,280 feet.^ Dawson mentions 

 one boulder of Huronian quartzite 42 x 40 x 20 feet at an altitude of 

 'î,200 feet and suggests that these boulders were transported by floating 

 ice. 



Northwest from Calgary Tyrrell describes boulder clay with quartzite 

 pebbles, sandstone and coal, but no gneiss, overlying a bed of quartzite 

 pebbles from Little Red Deer river.^ 



Still farther northwest he finds the western limit of gneiss boulders 

 on the North Saskatchewan a little beyond Baptiste river, which is 

 about 70 miles northeast of the mountains,* so that the same general 

 relationship seems to hold as at Calgary. 



Going north from Calgary to Edmonton, a distance of more than 

 180 miles, the railroad soon leaves the valley of Bow river and gets more 

 and more distant from the mountains, which ran noithwest, until at 

 about half way, they are no longer visible and the country becomes a 

 flat or gently rolling plain, prairie towards the south but partly wooded 

 as one approaches Edmonton. At two or three points, such as Olds, 

 Penoka, and Wetaskiwin, moraiuic hills rise; and wherever boulder clay 



1 G.S.C., 1882-4, C. pp. 82 and 146. 



2 Ibid. pp. 147 and 8. 



3 Ibid, 1886, p. 140 E. 

 *Ibid. 1880, p. 142 E. 



