410 THE GLACIAL LAKE AGASSIZ. 



gravel and sand from 992 to 980 feet on the descending slope of till, is 

 crossed bj'the railway, and thence runs northward as a more definite ridge, 

 with crest at 992 to 995 feet, through the west half of section 12. The top 

 of the lower beach ridge, which lies an eighth of a mile to the west, run- 

 ning nearly along the west line of this section, is at 985 feet, with descent 

 of 2 or 3 feet eastward and al)out 10 feet westward. 



Through the next four townships to the north, extending 24 miles, the 

 Campbell shore-lines have not been exactly mapped, but their position is 

 known very nearly by the general westward descent of the border of the 

 lacustrine area toward the flat Red River Valley plain which forms its cen- 

 tral part. Near the middle of this distance, however, on the Northern 

 Pacific Railroad, two beach ridges, belonging to the Campbell stages, lie 

 between 3 and 3.^ miles west of Muskoda. The railroad profile shows that 

 the elevation of the eastern one of these ridges is 1,004 feet above the sea, 

 with descent of 4 feet east and 1 1 feet west in its width of 30 rods, and 

 that the crest of the second ridge is at 1,000 feet, 7 feet above its east base, 

 while its west slope falls almost 20 feet, the whole width of this beach 

 being about 50 rods. The unusually massive development of the Campbell 

 beaches here, and of the closely associated McCauleyville beach, is due to 

 their derivation partly from the delta of the Buffalo River, and in larger 

 part from exceptional erosion in the slope of till that formed the lake shore 

 northward. This slope is strewn with many bowlders, the remnants from 

 a considerable depth of till worn away by the lake waves. 



In Hagen the Campbell shore is mainly traced by a line of erosion 

 forming a somewhat steep escarpment, from 5 or 10 to 25 feet in height, 

 near the foot of the slope of till which thence rises gradually toward the 

 east; but beach gravel and sand deposits mark its course where it crosses 

 the depression occupied by the South Branch of the Wild Rice River. 

 Likewise through Rockwell this lake margin is an eroded till escarpment. 



The shore again bears a well-defined gravel ridge in Lake Ida Town- 

 ship, passing from the southeast quarter of section 34 north-northeastward 

 across section 26 to the Wild Rice River, and thence nearly due north 

 through the west edge of sections 13, 12, and 1, there rising 6 to 8 feet 

 from its eastern base and descending 20 feet toward the west. The height 



