DEPOSITS IN VICINITY OF BELLY RIVER 705 



acter of the underlying deposit, suggests that the drift composing the 

 bench was deposited under the same conditions as that capping the flat- 

 topped ridges and mesas at a pre-Wisconsin stage of glaciation; that 

 during the later extension of the Belly Eiver glacier a tributary ice- 

 stream, heading in the cirques above, cut through the bench, forming 

 the broad sag, and that, after the melting of this glacier and that in the 

 valley, post-glacial drainage cut the sharp notch. 



Going northward along the slope to a point about one-half mile south 

 of the international boundary, another similar bench is found at about 

 the same elevation, with an exposure in the steep marginal slope, showing 

 glacial till similar to that described above. The sides of the valley are 

 heavily wooded and no detailed examination of them was made, so that I 

 am not prepared to say what was the upper limit of the last glaciation, 

 but I doubt very much if it overlapped these high-level deposits. These 

 benches stand like remnants of high level terraces and appear to repre- 

 sent a former stage in the development of the valley. 



Crossing the line into southern Alberta, high, straight-topped ridges 

 like those described above were seen, one on either side of Belly Eiver 

 and one east of Lower Waterton Lake. Unfortunately, however, owing 

 to a heavy fall of rain and snow, we were unable to examine the tops of 

 these ridges. Seen with field glasses from the valley below, there ap- 

 peared to be a heavy capping of coarse gravel on the ridges bordering 

 Belly Eiver, and since seeing the other high-level deposits I will be sur- 

 prised if there are not on these ridges remnants of the same pre-Wis- 

 consin glacial drift. 



Age of the High-level Drift 



Until further investigation of the relations of these deposits have been 

 made no satisfactory conclusions can be drawn as to their full signifi- 

 cance. As stated above, these flat-topped tracts have been regarded as 

 remnants of a late Tertiary peneplain. If the widespread "quartz ite 

 gravels" capping these elevated tracts away from the mountains are to 

 be correlated with this older glacial drift, then we may infer that the 

 drift was deposited prior to the dissection of the Blackfoot peneplain, 

 since the gravels must have been deposited prior to such dissection. TIk^ 

 presence of glaciated pebbles in the deposit capping Milk Eiver Eidge, 

 the most typical remnant of this Blackfoot peneplain, and their presence 

 also in the type exposure of the 'TCennedy gravels" certainly point to 

 such a correlation. If the valleys between these high-level tracts havo 

 been excavated to depths of 900 to 1,600 feet, and the headward'exten- 



