902 GEOLOaY OF OHIO. 



is well developed at several points in Green township, Hooking county, 

 and especially on Kitchen Run. In the vicinity of Junction City, 

 many thousands of tons have been raised. It is also found in Vinton 

 county, but has not been noticed south of the Marietta and Cincinnati 

 road. Its position is easily remembered on account of its relation to 

 the Blue or Zoar Limestone, the main seam of which it underlies by 

 fifteen feet, and the lower seam of which it covers when the latter is 

 present. It yields forty per cent, of iron and is in every respect a valua- 

 ble element of our geological scale. 



5. The next ore in ascending order is one of the most widely dis- 

 tributed and important of our whole series. It is the block ore which 

 immediately covers the main Zoar Limestone, and is designated in the 

 section as the Main Block. Situated thus in the most conspicuous horizon 

 of our Lower Coal Measures, it is universally known and through con- 

 siderable districts is styled the block ore, although it is never the only 

 seam of this class. Under cover, it is often a close-grained, heavy blue 

 carbonate, but along its outcrop, it is everywhere an easily worked and 

 excellent limonite. It agrees in general character with the ore last 

 described, like it yielding forty per cent, and over, of iron in the furnace. 

 It seldom exceeds a foot in thicknes and eight inches will make a very 

 satisfactory average wherever it is worked. Though ore is always shown 

 at this horizon, it is by no means to be concluded that the ore is always 

 valuable. There are very many areas in which it is too thm or too sili- 

 cious to have any value. It shows its marine origin in some instances 

 by containing fossil shells. Such a phase of it is seen at the old Hocking 

 Furnace, at Haydonville. It shares this peculiarity with the seam next 

 to be named. 



It is co-extensive with the limits of the limestone but it does not disap- 

 pear with that formation. The limestone is lost in Scioto county, a few 

 miles north of the Ohio River, but the ore retains its place with perfect 

 regularity and furnishes the means of identifying the various elements 

 of the scale that are associated with it. It is the lowest of three block 

 ores that are extensively worked among the southern furnaces, and when 

 all three are worked on the same lands, this ore is generally known as 

 the " little block " or '' little red block." It must, however, be confessed 

 that the same terms are sometimes applied to the other ores of the 

 series. 



6. Following the Upper Main Block Ore at an interval of twenty-five 

 to forty feet, quite a persistent seam occurs, the most common designa- 

 tion of which is the Rough Block Ore. It is also called the Sand-block, 

 but neither name is distinctive. It has been worked to a small extent 



