GEOLOGICAL REPORT. 89 



boring mines will be vastly increased, as there will be no fear 

 of exhausting them. 



The unfavorable opinion respecting the Lead Mines of Mis- 

 souri, which has prevailed to some extent among foreign mi- 

 ners and capitalists, has arisen, I apprehend, from the erroneous 

 opinions of some geologists that our mines have characteristics 

 and geological relations similar to those of the Wisconsin mines. 

 While I shall not deny that some of our lead veins resemble 

 those of Wisconsin, and appear like Gash-veins, there are many 

 others in which the analogy does not hold good in any one im- 

 portant character. 



1. According to Mr. Whitney, the valuable Lead veins of 

 Wisconsin are confined to a formation not more than 100 feet 

 thick ; but in Missouri the most valuable veins range through 

 three formations, the aggregate thickness of which is not less 

 than 1,000 feet. 



2. In Wisconsin the Lead veins are limited to one formation 

 in the upper part of the Lower Silurian System, while in Mis- 

 souri the most valuable veins range through two members of 

 the Carboniferous system and the two lower formations of the 

 Silurian. 



3. While in Wisconsin, so far as I know, there are no eviden- 

 ces of extensive igneous action or violent disturbances in the 

 neighborhood of the lead mines, in Missouri, both within and 

 around the lead field, there are most decisive proofs of exten- 

 sive igneous action and violent disturbances mountains of 

 granite and porphyry have been thrown up mountains and 

 ridges of porphyry have been fractured and rent asunder, and 

 the fissures filled with dykes (veins) of granite, greenstone, 

 quartz, basalt, dolerite and porphyry, and true veins of copper 

 and wolfram,* and veins (where the metalic ore fills the entire 

 fissure) of specular iron and galena ; some of these dykes pass 

 into the sedimentary rocks, changing the sandstone to quart- 

 zite and the limestone (the lower lead-bearing beds) into crys- 

 talline marble. 



4. In Wisconsin the profitable veins have not extended more 



* Dr. Norwood is my authority for these veins of copper, wolfram and dol- 

 erite. 



