SECTIONS IN BOW RIVER VALLEY. 53 



gravels appear again. They consist mostly of rounded quartzite pebbles 

 and boulders, ranging in size from one to twelve inches in diameter, and 

 have a thickness of eight feet. The pebbles increase in size toward the 

 base of the formation. The boulder-clay above the gravel holds occa- 

 sional gneissic pebbles, but they are small and scarce. 



" Two miles above the last exposure the pebble bed passes into dark 

 clays filled with stones of western origin only. Above this is 170 feet of 

 boulder-clay, alternating in places with sandy layers. A mile below the 

 mouth of Fish creek the gravels reappear, but are replaced a mile above 

 Fish creek by stratified sands. Two miles farther on the sands pass into 

 gravels again, and these continue to underlie the boulder-clay as far as 

 Calgary. West of Highwood river the western gravels underlying the 

 boulder-cla}^ consist of limestone and quartzite, the proportion and size 

 of the former increasing as the mountains are approached, but east of 

 Highwood river they are composed almost entirely of quartzite. The 

 gradual diminution in size of the limestone pebbles and their final dis- 

 appearance to the east, while the quartzite constituents still continue, is 

 no doubt due to their inferior hardness and consequent inability to stand 

 the wear attendant on a lengthy journey under the conditions in which 

 it was accomplished. 



" The Saskatchewan gravels and associated sands and clays in the 

 neighborhood of Fish creek are everywhere overlain by boulder-clays 

 holding scratched limestone and quartzite pebbles and boulders from the 

 west, and at rare intervals small gneissic pebbles from the east." 



In my own descent of Bow river, in 1881, attention was chiefly devoted 

 to the underlying rocks, but to the above description by Mr McConnell 

 it may be added that the existence of the Saskatchewan gravels, though 

 obscured by slides, was suspected at some places below the Blackfoot 

 crossing.* Above the crossing these gravels appear sometimes at the 

 water-level and sometimes at heights from 20 to 60 feet above it, but it 

 is probable that if carefully looked for they might be recognized at short 

 intervals all the way down to Medicine Hat. 



At Calgary, on the north side of Bow river about a mile below the 

 bridge, a very instructive and clear section occurs. This had been exam- 

 ined by Mr McConnell in 1890, and was in 1894 carefully reexamined by 

 that gentleman and myself It shows in descending order : f 



Feet 



1. Irregular deposits of gravel and silty soil 5 



2. Stratified silts, with some lenticular layers of boulder-clay ; striated stones 



and small boulders in both 35 



* Report of Progress, Geol. Survey of Canada, 1882-'8'1, pp. 141 C, 142 C. 

 t Elevation of base of section, 3,390 feet. 



