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



It will be noted that the Laurentian drift is in this neighborhood 

 markedly more abundant at the higher levels, the upper limit of the 

 traveled material standing above all the hills and ridges to the eastward. 

 A distinct terrace was observed on the opposite (west) side of Beaver 

 Creek valle_y at an estimated height of about 5,130 feet. This may pos- 

 sibl}'' correspond with that previously noted as seen from the hills above 

 Oleson creek, but is not the same. The levels in both cases are neces- 

 sarily somewhat uncertain. 



In crossing the last ridge of the Porcupines on the west, between Beaver 

 creek and the North fork of Oldman river, a height of 4,986 feet was 

 reached, and here a few pebbles of Rocky mountain origin were found, 

 although on projecting points 200 feet higher no traveled drift was ob- 

 served. This evidence is, however, of a purely negative character. On 

 the west slope, in descending toward the North fork, Laurentian drift 

 was first recognized at 4,710 feet and continued sparingly down to about 

 4,060 feet. None was seen near the river itself (3,960 feet). 



Plain and Valley Wp:st of the Porcupine Hills. 



Between the Porcupines and the foothills proper a plain some miles 

 in width here runs north and south. This to the eye ap])ears almost 

 perfectly level. It is continued southward beyond the INIiddle and South 

 forks of the Oldman with increasing width and probably with a some- 

 what decreasing elevation. The lowest part of this plain actual!}^ trav- 

 ersed on our route is near tlie confluence of the Nortli and Middle forks, 

 with an elevation of 3,750 feet. In about three miles farther north it 

 rises gradually to 4,140 feet, the surface being generally gravelly (num- 

 ber 1 of section on page 42). This gravel plain resembles in character 

 that occurring near Macleod at an elevation lower by about 1,000 feet, 

 but no eastern drift was found among the peb])les, wliich appear to have 

 been entirely brought down by rivers flowing from the mountains. 



In following the i)lain northward it becomes narrowed, but again widens 

 about the bend of the North fork, where its average elevation is about 

 4,200 feet. From this vicinity (near the Upper Walrond ranch) the wide 

 valley of North fork runs northwestward to the base of the mountains. 

 It is floored by a regular terrace, apparently in continuation of the plain 

 last referred to, which attaches to the bases of the neighboring hills some 

 miles to the west at an elevation of about 4,400 feet. 



From the Upper Walrond ranch a continuous valley, bounding the 

 Porcupine hills on the w^est, runs northward to Highwood river, a distance 

 of 48 miles. A very few small Laurentian boulders were seen near the 

 ranch, and one was observed about a mile and a half to the north at a 



