416 THE GLACIAL LAKE AGASSIZ. 



Slieyenne, is traced as a low, eroded escarpment of till, 10 to 15 feet in 

 height, with base at 9'J5 feet. 



Four to G miles north of its bend the Campbell shore is compound 

 and irregularly developed, bearing three beach ridges of gravel and sand, 

 which rise 5 to 10 feet above the adjoinhig surface of till and range from 

 986 to 1,000 feet above the sea. The uppermost forms a northwardly 

 projecting spit in the southwest quarter of section 4, Walburg, on which 

 Mr. Luther Wyckoff's well found sand and gravel to the depth of 10 feet 

 and till beneath. Along its course of 6 miles onward to Wheatland some 

 portions of this shore are marked by beach gravel, with crest at 992 to 995 

 feet; but commonly there is no beach deposit, its place being occupied by 

 a somewhat steep descent toward the east, falling from 990 or 995 feet to 

 about 975 feet, eroded in the general sheet of till. Below this a tract a 

 half mile or more in width is fine lacustrine silt, descending eastward with 

 less slope. 



In the east part of Wheatland village the Northern Pacific Raih-oad 

 intersects the Campbell beach a quarter of a mile from the station. A 

 massive gravel and sand ridge here occupies a width of about 60 rods, 

 including its slopes, and rises 15 feet above the nearly level expanse thence 

 eastward. Its crest, at 994 feet, is 10 feet above the hollow, 40 rods wide, 

 on its west side. This ridge appears to have been formed during the lower 

 and more important of the Campbell stages of the glacial lake, when its 

 level was about 990 to 985 feet. The accompanying upper shore-line, 

 which should be looked for 10 to 15 feet higher, crosses section 15 between 

 2 and 3 miles north of Wheatland, where Mr. Joseph Fuller's house is built 

 on the top of its beach ridge, about 1,012 feet above the sea. His well 

 was dug 15 feet in sand and gravel, then passing into till. 



North-northeastward from Wheatland the crest of the lower and prin- 

 cipal beach holds a nearly constant elevation, varying in the first 3 miles, 

 to Swan Creek, from 993 to 996 feet, with descent of 12 to 15 feet in 20 

 rods east, and usually 3 to 5 feet in 10 rods west. About two-thirds of its 

 gravel, which has pebbles and cobbles up to 4 inches in diameter, are lime- 

 stone; three-tenths, by estimate, are granite and other crystalline rocks; 

 while about a thirtieth part is Cretaceous shale. Looking east from this 



