470 THE GLACIAL LAKE AGASSIZ. 



North of Lake Winnipegosis, the Ossowa shore on the ascent of the 

 eastern Mossy portage, as described by Mr. Tyrrell, takes the form of an 

 escarpment, with its crest 63 feet above this lake, or 891 feet above the sea. 

 It was probably eroded by the waves of Lake Agassiz when its snrface 

 there was approximately at 875 feet, midway between its Burnside and 

 Stonewall levels at this locality. 



THE STONEWALL BEACH. 



In the town of Stonewall, Manitoba, the main street crosses a conspic- 

 uous beach ridge which runs from south-southwest to north-northeast a 

 third of a mile or more. Its crest is 820 to 825 feet above the sea, and its 

 depth is about 10 feet. Only 2 or 3 feet of till intervene between this 

 gravel and sand and the underlying limestone, which, thinly covered by 

 drift, rises in a swell here about 25 feet above the adjoining country a half 

 mile distant to the east and west. Beach deposits belonging to this stage 

 were not elsewhere observed in southern Manitoba, but they are doubtless 

 traceable from Stonewall northward through the west half of townships 14 

 and 15, range 2 east. Lake Agassiz, at the time of the Stonewall beach, 

 probably extended on the flat Red River Valley to a distance of about 

 25 miles south of the international boundary, being some 15 feet deep at 

 Emerson, St. Vincent, and Pembina, while over the site of Winnipeg its 

 depth was about 60 feet. 



A somewhat ridged contour upon the otherwise very flat surface of fine 

 alluvial silt was noted 6 to 7 miles east of Hamilton and Bathgate, N. Dak. 

 The wave-like and almost beach-like tmdulations, rising 2 to 4 feet above 

 the depressions which separate them and above the general level, run north- 

 northwestei'ly through the east part of section 11 and the central part of 

 section 2, township 162, range 52, close southeast of the Tongue River. 

 Similar contour was also noticed in the continuation of this course within a 

 few miles northward between the Tongue and Pembina rivers. The height 

 of tills belt is about 805 feet above the sea. 



On the eastern Mossy portage the crest of the Stonewall beach, as 

 observed by Mr. Tyrrell, is 27 feet above Lake Winnipegosis, or 855 feet 



