560 PKE-W1SCONSIN GLACIAL DRIFT IX MONTANA 



A. Stratified, water-worn gravels ("Saskatchewan"), pebbles exclu- Feet 

 sively quartzite and other rocks from the Rocky Mountains, 

 ranging in size from fine to 6 inches in diameter. Partially 

 cemented, fine material fills the interstices and streaks of cross- 

 bedded sand occur in places. The upper 1 foot of the gravels 

 is oxidized to a dull orange tint, as though marking a zone of 

 weathering. Bottom not exposed 15 



At none of the sections examined farther up this stream were the 

 gravels exposed. In fact, although the stream has cut 60 to To feet in 

 drift below the level of the plain, at several places examined within a few 

 miles of Hillspring village (township 4 north, range 2T west) it has not 

 yet reached the bottom of the till of the Keewatin ice-sheet excepting at 

 one place, where it swings against the side slope of the preglacial valley. 

 Farther up the valley, where the stream cuts through the terminal mo- 

 raine of the Keewatin Glacier and beyond this moraine, the stream fre- 

 quently exposes the Cretaceous sandstones and shales underlying the 

 drift, but nowhere are "quartzite gravels"'" present. Xeither were the 

 "quartzite gravels'*'" found intercalated between the drift and the Cre- 

 taceous rocks at the exposures examined on Drywood Fork of Waterton 

 Eiver. Xo sections were examined on the TVaterton excepting in the 

 vicinity of its confluence with Belly Eiver. 



At most of the exposures examined on South Fork of Oldman River 

 west of Pincher (townships T and 8 north, range 30 west) till rests di- 

 rectly on the Tertiary ( ? ) sandstones or shales with no intervening 

 "quartzite gravels."'" At the point between the South and Middle forks 

 near their confluence 25 feet of loose buff till was exposed, a small per- 

 centage of the pebbles in which were Laurentian crystallines, overlying 

 35 feet of somewhat denser till, lighter buff in color and containing, so 

 far as noted, only pebbles of rocks from the Eocky Mountains and beneath 

 this sandstone. Looking back up the stream to an exposure which was 

 not closely examined, it was seen that at that place 10 to 15 feet of strati- 

 fied gravel intervenes between the lower bed of till and the Tertiary beds. 



Dawson 19 describes three sections where similar gravel underlies the 

 mountain till, one at a point on Xorth Fork of Oldman, 2 miles north of 

 its junction with Middle Fork; a second on South Fork of this stream, 

 at a point about 12 miles from the mountains, and a third still nearer the 

 mountains on Mill Creek. Concerning these he writes : 



"The two last-mentioned localities are within the limit of the country char- 

 acterized by moraines, evidently due to local glaciers from the Rocky Moun- 

 tains, and the indurated boulder-clay of the Mill Creek section is believed, like 



" Bull. Geol. Soc. Am., vol. 7, p. 43. 



