42 G. M. DAWSON — GLACIAL DEPOSITS OF SOUTHWESTERN ALBERTA. 



foliated leathery clays. The lower part of the boulder-clay is darker 

 in color than the upper, but there is no division into upper and lower 

 members, as dark and light layers alternate and change in color when 

 followed along the bank. Stones both of western and eastern origin 

 occur throughout, the former preponderating toward the bottom and the 

 latter toward the top. The mass of the boulder-clay is in some places 

 hard and clayey, in others soft and sandy, that of the last mentioned 

 character passing occasionally into layers of sand and gravel." 



The stratified sands, silts and leather}^ cla3^s or shales of the above 

 section much resemble the interglacial beds of I.ethbridge, but, as already 

 stated, there is here no means of certainly identifying the boulder-clay- 



Farther up along Oldman river, at the mouth of Beaver creek (28 miles 

 from the mountains, elevation about 3,260 feet), a bank examined by 

 Mr McConnell shows, above the river level, " 50 feet of compact boulder- 

 cla}^ overlain by 6 feet of stratified silts and sands. There is here a marked 

 diminution in the proportion of eastern drift as compared with the last 

 section, a rough estimate making it about two per cent of the whole." 



In the same vicinity, on Oleson creek, about 400 feet above the river 

 and to the north of it, a moderately indurated pale drab silty or sandy 

 boulder-clay was found holding com[)arativel\^ few stones, but some of 

 them distinctly glaciated. 



Still further to the westward, at the confluence of the North and Middle 

 forks of the Oldman (about 15 miles from tlic line of tlie base of the 

 mountains, elevation approximately 3,650 feet), a good section was found, 

 which may be set out as follows in descending order: 



Feet 



1. Well rolled and rounded gravels, with some stones as much as 8 or 10 inches 



in diameter, ai)i)arently all of Rocky mountain ori^nn 10 



2. Good typical boulder-clay, moderately indurated ; matrix brownish yellow 



and earthy, containing glaciated stones and boulders of moderate size, 

 mostly suban<2:ular, but some well rounded, derived from the mountains 

 or from the Cretaceous rocks of the foothills, but chietiy quartzites ; some 

 limestone an<i a few examples of jjreenstone. Two or three small i)ieces 

 of Laurentian rocks were found which probably came from this boulder- 

 clay 20 



3. Stratified, earthy, brownish yellow sands, containing a few glaciated stones. 10 



4. Obscurely stratified gravels, containing some stones 10 inches through, all 



well rounded and like beach or river shingle. Traces of glaciation were 

 suspected on a few of these, but Mere in no case observed to be abso- 

 lutely decisive. The line between this and the overlying deposit is quite 

 regular and definite. Althoujjh there is an appearance of l)lending in a 

 thickness of a few inches, there is no sign of any intervening condition 

 of importance 10 



5. Laramie sandstones and shales to river level 40 



90 



