278 SPARKS FROM A GEOLOGIST'S HAMMER. 



that that portion of the rock series which, in Illinois and 

 Wisconsin, embraces the ores of lead, is identical with a 

 portion of the rock formation which occurs in the north- 

 ern part of our state" (p. 10). Now, the lead ores referred 

 to are found in the lower silurian, while the Michigan 

 rocks are Hamilton and Corniferous, in the Devonian. It 

 is not pretended that such errors of identification reflect 

 the least discredit upon their author ; but, being facts, 

 they show the impossibility of a truthful conception of 

 the geological relations of the brines of the peninsula. 



Messrs. Hubbard and Douglass devoted their attention 

 to the lower peninsula, while Dr. Houghton was mostly 

 occupied with the upper peninsula. The assistants, there- 

 fore, acquired a more thorough acquaintance with the 

 lower peninsula, and I never look over their reports with- 

 out a feeling of admiration for the general accuracy at- 

 tained, in the face of the gigantic difficulties presented 

 by the unsettled and unimproved condition of the country. 

 But these assistants never attained an entirely correct 

 correlation of the formations on the eastern, western and 

 southern slopes of the peninsula. 



The first attempt at a systematic general account of 

 the stratification of the peninsula was made in 1840, by 

 Mr. Hubbard.* In this he reached several important 

 conclusions, which, under the authority of certain later 

 geologists, were ignored, but which, with a more thorough 

 acquaintance with Michigan geology, have been admitted 

 as sound. The northern outcrops of the formations of the 

 peninsula were not reported on by him until 1841.t In 

 his attempt to assign them to their proper stratigraphical 

 positions he fell into singular errors, and introduced into 

 * Mich. Geol Rej). 1840, p. 87. t Mich. Geol. Bep. 1841, pp. 115, 136. 



