280 SPARKS FROM A GEOLOGIST'S HAMMER. 



ern part of the state, and consequently failed to identify 

 the underlying shales. In the next place, Mr. Hubbard 

 identified with the Point aux Barques shales the shales 

 of the Michigan Salt Group struck in the salt wells at 

 Grand Rapids, although these latter actually occupy a 

 position above the Marshall sandstones. When, therefore, 

 these sandstones and the underlying Huron shales were 

 struck in the boring of the salt wells, they were supposed 

 to constitute the third couplet of similar strata, and are 

 set down as groups H and I in the above table.* 



It is manifest from these documentary proofs that there 

 were not in existence at the period when Dr. Houghton 

 gave personal attention to the geology of the peninsula, 

 and formed his judgments on the geological relations of 

 the salt springs, any such correct conceptions of the basin- 

 structure of the peninsula, the geological origin of the 

 brine, the mode of occurrence of the brine springs, or the 

 general geological constitution of the peninsula, as ren- 

 dered possible the belief that the lowest depression of the 

 salt basin (or basins) of the peninsula would be found 

 under the Saginaw valley. Dr. Houghton's procedures- in 

 locating the two state artesian salt wells are in accord- 

 ance with the evidence cited, and are of themselves suffi- 

 cient to prove that he did not entertain the belief ascribed 

 to him. If such beliefs were held, why did he not con- 

 centrate his efforts in the Saginaw valley? Why locate 

 one well on the Tittabawassee and the other on the west- 

 ern slope of the peninsula? I have heard one solution 

 of the mystery, which no friend of Dr. Houghton, and in- 

 deed no person cognizant of his personal integrity, would 

 feel disposed to urge or to credit. I have heard that 

 * Report, p. 133. 



