426 THE GLACIAL LAKE AGASSIZ. 



on the west about 2 miles wide separates them from the base of Riding 

 Mountain. 



Mr. Tyrrell's observations and map of the beaches of Lake Agassiz 

 adjacent to the northern part of Riding Mountain and on the eastern and 

 northern sides of Duck Mountain, as correlated with my mapping from 

 Lake Traverse to the southern end of Riding Mountain, show the principal 

 Campbell shore, there probably the upper one, to be marked by a promi- 

 nent gravel ridge, which Mr. Tyrrell has traced through distances of many 

 miles.^ The elevation of this beach ridge where it crosses the Ochre River, 

 on latitude 50° 56', is 1,115 feet above the sea. On the Valley River, 

 about 30 miles farther northwest, its height is 1,135 feet. Twenty miles 

 thence northward, on Shanty Creek, this shore has two beach ridges, 

 respectively 1,180 and 1,190 feet above the sea. The lower one of these 

 beaches has been followed continuously 15 miles to the north, attain- 

 ing there an elevation of 1,225 feet. Nearly 20 miles farther north, the 

 elevation of the Cam])bell beach at its most northern observed localit)^, 

 on latitude 52°, is 1,290 feet, perhaps corresponding to its upper ridge on 

 Shanty Creek. 



This well-defined, massive gravel ridge, double in portions of its course, 

 is doubtless the continuation of the similar beach which is called the Beau- 

 tiful Plain and Orange Ridge, ha^^ng at Arden an elevation of 1,090 feet 

 above the sea. For the distance of about 70 miles north from Arden to 

 the Ochre and Valley rivers its ascent continues somewhat as from the 

 international boundary to Arden, averaging two-thirds of a foot per mile. 

 But northward from Valley River to Diick River, in a distance of about 

 55 miles, between latitudes 51° 13' and 52°, this beach rises 145 feet, or 

 more than 2^ feet per mile. After the Campbell stages of Lake Agassiz, 

 the southern part of the lacustrine area was only slightly uplifted; l)ut the 

 region of Duck Mountain subsequently experienced a greater differential 

 uplift, increasing in amount from south to north, than that of the earliest 

 Herman beach farther south, where nearly all of its inclination had taken 

 place before the Campbell beaches were formed. 



'Pages 39i) and 406, this chapter. Geol. and Nat. Hist. Survey of Canada, Annual Report, new 

 series. Vol. Ill, for 1887-88, Part E ; 16 pages, with map. Bulletin, G. S. A., Vol. I, 1890, pp. 395-410. 

 Am. Geologi.st, Vol. VIII, pp. 19-28, July, 1891. 



