SUPPLEMENTAL EEPOET — HANGING BOCK DISTRICT. 903 



m Perry county, and also in Jackson county, but it is nowwhere verj 

 highly esteemed. It is easily traced and thus helps to connect the sec- 

 tions of quite distant localities. 



7. Prom ten to twenty feet above the seam last named, another block 

 ore occurs. Its place is made quite conspicuous by its association with 

 the limestone and flint called Gore, in the present classification. The 

 place of the ore is immediately above the limestone or flint. It is often 

 wanting, but a good deal of iron is found at this horizon. The limestone 

 itself IS highly ferruginous. The ore is variously designated, its name 

 changing with its quality. It is called Sand-block more frequently than 

 anything else, but in many localities, it is counted valuable. It often 

 resembles the main block ores so much as to be confounded with them. 



Near Hamden, Vinton county, it is known as the Robbins ore. It is 

 there fossiliferous, containing sometimes beautifully preserved brachiopod 

 shells, thus proving its marine origin. Prof. Andrews called attention 

 to this interesting fact in the Report of 1870. 



There are in the Vinton county section two or three seams of block 

 ore above the one now named, but it is not certain that they are persistent. 

 In Scioto county, and in the western part of Lawrence, three block orea 

 make a considerable contribution to the supply of the furnaces located 

 there. The lower one of them is the Upper Main Block, that covers the 

 Zoar or Blue Limestone. Whether the second, which is known as the 

 Sand-block, agrees with the seam here described as the rough block No. 

 6, has not yet been determined. It is either this or the one now under 

 consideration, No. 7. If it is the rough block, then the upper ore of the 

 three which is locally known as the red block or big red block holds the 

 place of the Gore limestone and ore. It lies from ten to fifteen feet 

 above the middle block. 



The intervals all expand somewhat as they are followed southward, 

 and, unless frequent sections are taken, there is danger of confounding 

 diflerent elements of the scale. 



The red block of Scioto county becomes the main block of the, Ohio 

 Valley. Its position is determined by its relation to the limestone ore 

 which is everywhere known and worked. It is about one hundred feet 

 below this horizon. 



On its western outcrops, where it lies high in the hills and under light 

 cover it is often w !athered into an excellent ore — quite as good as the 

 ores of the same class just enumerated, but at many points, and notably 

 in the neighborhood of Ironton, it is a very close-grained, dark blue 

 carbonate, which has thus far proved intractable, having been tried only 

 in charcoal furnaces. It is found here in fine volume, measuring two 



