264 SPARKS FROM A GEOLOGIST'S HAMMER. 



the Saginaw Enterprise in February. The East Saginaw 

 salt well was completed February 24. It was 669 feet 

 deep, and yielded brine of 94. It had reached the solid 

 rock at the depth of 92 feet, and after passing through 

 the coal measures, with their initial and terminal sand- 

 stones, pierced the carboniferous limestone, and found the 

 Michigan Salt Group of strata 169 feet thick, and emi- 

 nently saliferous, though from the compact nature of the 

 formation the brine was very limited in amount. In the 

 Napoleon sandstone beneath, 109 feet thick, the reservoir 

 of the brine was struck which furnished an abundant 

 supply, and was obtained at almost precisely the point 

 which geology had predicted. The well terminated near 

 the middle of the sandstone. On June 12 I ac^ain visited 

 the salt works. Preparations were making to bore a sec- 

 ond and larger well. This was subsecjuently carried to 

 806 feet, extending through the sandstone and penetrating 

 the underlying shale 64 feet. By July, 1860, a "block" 

 had been erected, and boiling commenced. Before the 

 close of the year 4,000 barrels of salt had been manufac- 

 tured, and four other companies had commenced boring 

 at diiferent points along the river. 



During the season of 1860 careful geological explora- 

 tions were conducted around the Michicjan shores of Lake 

 Huron and the islands at the head of the lake. Thus the 

 correct view of the geology of the peninsula was more per- 

 fectly defined, and more permanently settled. The most im- 

 portant determination in this connection was the identifi- 

 cation of a great development of the gypseous formation of 

 the state in a high ridge which approaches near the lake 

 about four miles south of Tawas. The gypseous series 

 had been traced in the salt-boring at East Saginaw, and 



