532 



THE GLACIAL LAKE AGASSIZ. 



where the reported pressure is i^robahly erroneous, hickhiy lOt) pounds or 

 more of its true amount. At Hitchcock the head of water has a computed 

 altitude of 1,743 feet above the sea; 18 miles to the south, at Huron, it 

 is 1,691 feet; 22 miles farther south, at Woonsocket, it is 1,661 feet; and 

 81 miles still farther south, at Yankton, it is only 1,325 feet. Fig. 3-4 illus- 



Fig. 34 Section showing the series of artesian wells Irom Devils Lake and Jameato^ u southward to Yankton and 



Vermillion. Horizontal scale, 75 miles to an inch. 



trates this relationship of the series of artesian wells extending from north 

 to south in the James River Valley. 



Equally distinct gradients of the plane of watei- head are found descend- 

 ing from west to east on and near the latitudes of Huron and Yankton. 

 Thus at Harold, 75 miles west of Huron, the head is 1,986 feet above the 

 sea; at Higlnnore, 15 miles east of Harold, it is 1,948 feet; at Miller it 



DAHO tA: '■ ■■ S/^/yps ro.f^A: 



Flu. 35.— Section showing the series of artesian wells li-om Harold eastward to Huron. Horizontal scale, 15 miles to 



has decluied 73 feet in a distance of 22 miles farther to the east; and in 

 the 38 miles thence to Huron it falls 184 feet more. The relationship of the 

 wells at these places is shown in Fig. 35. From Kimball to Plankinton, in 

 24 miles from west to east, the water head declines 156 feet. Between Fort 

 Randall and Yankton, in a distance of 60 miles from west to east, this plane 



