94 



LOWER PENINSULA. 



carried deep enough, under the preconceived false impression that 

 the salt brine had its site in the higher gypsiferous rock series, in 

 the Michigan salt group of Winchell. 



In the borings at Muskegon, salt brine was found at a depth of 

 1250 feet from surface, which would appear to come from the 

 Waverly group ; the salt brine found at the depth of 2400 feet in 

 all probability is within the rock series of the Onondaga group. 



There remain yet to be given some accounts of borings executed 

 in the salt-producing districts of Saginaw valley. The salt wells 

 of Caseville have a very great depth; one of them is 1735 feet 

 below the surface, but, unfortunately, no record of the boring 

 was kept. I am informed, however, by persons who were pres- 

 ent when the boring was made, and who gave attention to the 

 matter, that the upper 900 feet went principally through a blue 

 shale, sometimes through red shales, with no important seam o 

 harder rock in the whole interval. At 900 feet, a large body of a 

 whitish sand rock was struck which contained strong brine ; another 

 supply of brine was found near the bottom of the well, likewise in a 

 sand rock. No limestone formation, or any other rock series in- 

 dicating a lower horizon than the Waverly group, was met with in 

 the boring, which commenced in the top part of the above-named 

 series, immediately below the incumbent gypsum formation. 



One of the first borings made in Saginaw valley, and at the same 

 time the most accurately recorded, is the well of the East Saginaw 

 Salt Mining Company. Dr. Lathrop, who kept the records, commu- 

 nicates to me the following details of it : 



Drift 92 ft. 



Sandstone 78^- " 



Dark shale , 26 " 



Light shale 14 " 



Sandstone with seams of coal 23 " 



Brine, 10 degrees salinonieter. 



Shales 1 2-|- " 



Sandstone with seams of coal 10 " 



Blue shales 36|- " 



Brine, 14 degrees salinometer. 



White sandstone 106 " 



Limestone, foetid 42 *' 



Sandstone , 5i 



1 " 



