DEPOSITS ON MILK RIVER RIDGE G95 



looks as though the ice emerging from the mountain valley extended this 

 high up on the slopes. Overtopping the proximal end of Milk Eiver 

 Eidge, the glacier appears to have spilled across the crest, extending a 

 small lobe about 2 miles northeastward down the slope on the north. 

 Perhaps this was assisted somewhat by ice descending from a fine big 

 cirque in the east slope of the mountain. Two well formed lateral mo- 

 raines are seen curving northward through the east side of a sag in the 

 crest of the ridge. Crossing this sag and climbing to the high flat top, 

 which here stands at an elevation of 6,100 feet above the sea, it appears 

 that the last ice just overtopped the north slope at the west end of this 

 part of the ridge and left there a small marginal ridge of drift. This 

 may be traced eastward about three-quarters of a mile on the top of the 

 ridge; it then drops down to a lower level and lies along the slope 100 

 feet or so below the top. On the high flat part of the top of the emi- 

 nence, beneath and beyond the little marginal ridge, is a deposit of 

 coarse gravelly drift yellowed with age and in which no limestone was 

 observed, although a massive bed of limestone is exposed in the moun- 

 tain slope to the west, and derived fragments are plentiful in the later 

 drift. It does, however, contain striated pebbles. The character and 

 relations of this deposit show that there is here another remnant of the 

 old high level drift. At the east end of this mesa an abrupt slope drops 

 down about 500 feet to a second sag in the crest li/^ miles in width. 

 This broad sag in the crest afforded another spillway for Cut Bank 

 glacier, and through this a tongue of ice extended northward a distance 

 of 3 miles into the Milk Eiver Basin, spreading out on the lower ground 

 as a lobe over 2 miles in width. This small lobe is designated the Milk 

 Eiver glacier by Mr. Calhoun.'^ 



Crossing this second sag and climbing about 350 feet up a steep slope 

 one reaches the top of the main part of Milk Eiver Eidge. From the 

 high west end one looks out over an extensive and remarkably smooth 

 plateau, sloping toward the northeast. In the first 1% miles the surface 

 declines 300 feet; beyond this there is a fairly uniform slope of nearly 

 80 feet per mile for 5^2 miles, the farthest distance to which the tract 

 was traversed by the writer. Fartlier east deepening ravines cut the 

 plateau into digitate, flat-topped ridges, and these in turn give place to 

 successively lower separated buttes. This elevated plateau is the best 

 preserved and most typical remnant of Mr. Willis's Blackfoot peneplain 

 seen by the writer. 



The drift of the "Wisconsin stage extends nearly to the top of the head 

 of the high level plain, reaching an elevation of 5,800 feet above the sea 



''Op. cit., p. 20. 



