80 THE GLACIAL LAKE AGASSIZ. 



Feet. 



Bluish and gray shale 20 



Eed shale or clay, inclosing much quartz sand 15 



Granite or gneiss, chiefly composed of quartz and red feldspar in rather small 



crystals 2 



Total 1, 037 



Alluvial and lacustrine silts and drift deposits reach a depth of 143 

 feet, the top of the bed-rock being 60 feet below the level of Lake Winnipeg. 

 Examining the succession of strata penetrated below, we confidently recog- 

 nize the thick limestone formation Avhich extends between the depths of 495 

 and 800 feet as the same that is found with nearly as great thickness in the 

 Humboldt well. It is referable, as Dr. Dawson concludes, to the Galena 

 limestone, passing below into the Trenton. In the distance of 30 miles 

 from Humboldt this limestone sinks somewhat more than 300 feet, aver- 

 aging between 10 and 11 feet per mile. Comparison with the Grafton well, 

 in which the base of this formation lies 73 feet higher than at Humboldt, 

 indicates an approximately west-northwest direction for the maximum dip 

 of the strata here, so that probably they sink at about the same rate, nearly 

 11 feet per mile, in the distance of 24 miles from Rosenfeld west to Morden, 

 as from Humljoldt northwest to Rosenfeld. Such inclination from the top 

 of the section under the drift at Rosenfeld would coincide very nearly (as 

 shown in PL XV) with the bottom of the Morden well, from which Mr. 

 Tyrrell reports fossils belonging to the lower part, probably the base, of 

 the Devonian series. 



From these considerations, it appears that the 192 feet of shales, lime- 

 stones, and sandstone shown by this section next below the drift must 

 represent the whole Upper Silurian series of this district, and that the 

 lower 100 feet of this thickness are probably the Guelpli and Niagara 

 formations. The lowest of these limestones, 30 feet thick, seems to be the 

 equivalent of the limestone of Stonewall and the top of Stony Mountain. 



The Lower Silurian series includes the next 160 feet of red shale, 

 belonging to the Hudson River formation; the 305 feet of Galena and 

 Trenton limestone; the underlying red shale and St. Peter sandstone, 

 together 125 feet thick; and, finally, 110 feet of shales, occupying the place 

 of the Lower Mag-nesian limestone. 



