78 THE GLACIAL LAKE AGASSIZ. 



Trenton age, found next beneath the drift in the Humboldt well, its upper 

 part here having been lost by arosion. 



The St. Peter sandstone occupies a thickness of 93 feet. 



Red, blue, and pink shales, representing the Lower Magnesian forma- 

 tion, ensue, with a thickness of 87 feet. 



The next stratum, 49 feet thick, is probably the equivalent of the 

 Jordan sandstone, the highest division in the St. Croix series of the Upper 

 Cambrian. Its thickness in southeastern Minnesota ranges from 40 to 116 

 feet, and in Wisconsin, where it is known as the Madison sandstone, it is 

 from 30 to 60 feet thick. 



The succeeding shales, having a thickness of 234 feet, appear to rep- 

 resent the St. Lawrence formation, the second in the St. Croix series, which 

 in southeastern Minnesota varies from 128 to 213 feet in thickness. 



Beneath the shales, the thin bed of water-bearing sandstone, lying on 

 the granite, may be a trace of the Dresbach sandstone, a tliird division of 

 the St. Croix, wliich has a thickness of 50 to 80 feet or more in southeastern 

 Minnesota. The brine rising from this bed was analyzed by Prof Hem-y 

 Montgomery, of the University of North Dakota, and was found to be 

 snore saline than sea water. 



Samples of the borings in the lowest 12 feet were submitted to Prof 

 N. S. Shaler, who pronounced them to be granite or gneiss, being the 

 Archean bed of the ocean in which the overlying Paleozoic strata were 

 deposited. 



The water used from this well is taken from the St. Peter sandstone, 

 the lower part of the bore ha-\ang been filled. The diameter of the pipe is 

 6 inches, and the flow, according to thi-ee measui-ements in 1886 and 1887, 

 during the first year after the completion of the well, was 800 gallons per 

 minute. 



WELL AT ROSENFELD, MANITOBA. 



Rosenfeld is situated 14 miles north of the international boundary and 

 11 miles west of the Red River, being 30 miles northwest of Humboldt, 

 and about 54 miles distant, in a direction slightly west of north, from 

 Grafton. Like Humboldt and Grafton, it is on the flat plain of the Red 



