SUMMARY AND DISCUSSION. 59 



be derived from these facts and their interrelation. These conclusions 

 are practically such as may directly be drawn from the region itself, not 

 complicated by attempted correlation with distant fields, nor will I 

 venture at the present time even to compare them with a scheme of 

 glacial events in the west which has ah^eady been tentatively advanced 

 by me. 



As implied in Mr McConnell's summary of the Bow River section, just 

 given, it may, I believe, now be stated with certainty that the earliest 

 sign of glacial conditions met with in southwestern Alberta is found in 

 the evidence of the extension of glaciers from the Rocky mountains to 

 a certain distance beyond the base of that range. These may have reached 

 nearly to Calgary, in Bow valley, which has the largest drainage basin in 

 the mountains, but were much less considerable farther south. A boulder- 

 clay was at this early time laid down in connection with these glaciers, 

 probably in part as a subglacial deposit, in part along their retreating 

 fronts as a fiuvio-glacial deposit. The latter as it is followed eastward 

 gradually changes into the typical Saskatchewan gravels, in places asso- 

 ciated with silty or sandy beds. All the drift material of this stage is 

 either local or derived from the Rock}^ mountain side, and it is probable 

 that the boulder-clay of this time is actually connected with the mass 

 of the moraine ridges and hills of Bow valley and those found fringing 

 the mountains in places farther to the south. 



Above the Saskatchewan gravels rests the lower boulder-clay of my 

 original report, containing mixed drift from the Laurentian plateau and 

 Winnipeg basin to the eastward and the Rocky mountains on the west. 

 Beyond the change of conditions implied by the differing deposits, no 

 evidence has been found to show that any long time-interval occurred 

 between the stage of the Saskatchewan gravels and that of the lower 

 boulder-clay ; nor can it be determined to what extent mountain drift 

 continued to be supplied from the west during the deposition of this 

 boulder-clay, as the preexisting Saskatchewan gravels have evidently be- 

 come incorporated with it in places to an unknown degree. 



Above this boulder-clay, and evidencing altogether different conditions 

 over a tract at least 50 miles in extent from east to west where cut across 

 by the Belly river, are well stratified intergiacial deposits, including 

 locally a thin bed of lignite. 



Succeeding the intergiacial deposits is the upper boulder-clay, which, 

 like the lower, contains mingled drift of eastern and western origin. 

 Above this and forming the surface of the plains are stratified loamy, 

 silty, sandy and gravelly deposits, which appear to have been laid down 

 in water and in and on which are scattered many of the larger erratics 

 met with in the district. 



