536 THE GLACIAL LAKE AGASSIZ. 



in the water of the artesian wells in the drift of the Red River Valley, as 

 well as of its saline springs, has been supplied du-ectly from the underlying- 

 Silurian formations, which, as stated in Chapter III, yield an artesian flow 

 of brackish water at Grafton, N. Dak , and flows of rather strong brine at 

 Humboldt, Minn., and Rosenfeld, Manitoba. The relationship of these 

 rocks to the adjacent Dakota sandstone suggests a qiiestion whether possi- 

 bly some of the salt in the water of this sandstone at Morden, Tower City, 

 Devils Lake, and along the James River Valley may have come from the 

 same source. The gradients of the head of the artesian wells of North and 

 South Dakota show, however, by their descent toward the east and south- 

 east, that the currents of water running through the Dakota sandstone come 

 from the Rocky Mountains and Black Hills, and that they hud egress by 

 springs in the Red River Valley and in the valley of the Missouri south- 

 east of Yankton. On account of the greater weight of saline than of fresh 

 water, this suljterranean drainage of the vast western plains may have con- 

 tributed much to the quantity and strength of the brine contained in the 

 deep reservoir of the Silurian strata beneath the bed of Lake Agassiz. It 

 seems to me, therefore, more likely that the Dakota .sandstone has been 

 chiefly a giver rather than a recipient of salt, in its relation to the Silurian 

 formations penetrated by the Humboldt and Rosenfeld wells. 



ANALYSES OF WATERS FROM WELLS, STREAMS, AND LAKES IN THE 

 RED RIVER VALLEY AND THE ADJOINING REGION. 



The following analyses show the composition of the mineral matter 

 which had been held in solution and was left after evaporation by the 

 waters of several wells, streams, and lakes in this region. The first column 

 in each analysis gives the proportion of the several ingredients to the 

 weight of the natural water in parts per million. In the second column 

 their percentages are stated, and the third notes the weight of each in 

 grains per standard gallon of the United States, containing 231 cubic 

 inches. Nos. 1, 3 to 7, and 10 to 12 were analyzed under the direction of 

 Prof. James A. Dodge, of the University of Minnesota, by his assistants, 



