90 GEOLOGICAL REPORT. 



than 100 feet in depth, but in Missouri, two shafts have been 

 sunk on the large Virginia vein to the depth of 260 feet, with- 

 out any diminution or indication that it would run out. 



5. In Missouri some of the veins do pass from the Limestone 

 into the Sandstone above, as seen at the Evans and the Caswell 

 Mines. 



6. Many of the veins in Missouri present all the appearances 

 of true veins ; dislocations and disturbances have been produ- 

 ced by powerful agencies, as indicated in some places by the 

 fragments of the original strata filling a part of the fissure, by 

 well marked and extensive slickensides, by the displacement of 

 the strata, and the irregularity of the fissure. 



7. The veins are often very long; some have been explored 

 more than one mile. 



8. In many mines the fissures are filled as they usually are 

 in true veins; the sheet of galena runs through the middle, 

 with a gangue of heavy spar or calc spar, or both, on each side. 



9. Selvages, so remarkable in true veins, also occur in the 

 Missouri mines. 



Such are some of the facts which should lead us to suspect 

 the validity of all arguments drawn from any apparent analogy 

 between the Wisconsin mines and our own. And besides, even 

 on the supposition that our veins do not extend below the base 

 of the 3d Magnesian limestone, there is still from 200 to 400 

 feet of this rock below the deepest workings of nearly all the 

 mines in the counties of Jefferson, Franklin, Crawford, and the 

 north of Washington ; while in the South-west the lead-bearing 

 portion of the Mountain Limestone is at least 200 feet thick. 

 Below these beds are the Chemung rocks, which are not over 

 100 feet in thickness. Whether the lead passes down through 

 this formation is not known, as no vein has been traced or 

 worked to it. The character of the rock, however, does not 

 indicate the existence of valuable veins, though some deposits 

 of lead and copper have been discovered in it. In passing from 

 the Chemung rocks near the northern boundary of Taney, we 

 come directly upon the lead-bearing rocks of that county, which 

 are the 2d and 3d Magnesian Limestones. The 1st and 2d 

 Sandstones are very thin or entirely wanting in this part of the 



