SUPPLEMENTAL REPORT—HANGING ROCK DISTRICT. 
in Perry county, and also in Jackson county, but it is nowwhere very 
highly esteemed. It is easily traced and thus helps to connect the seo- 
tions of quite distant localities. 
7. From 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. Th 
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 1s 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 ia 
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 ores 
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 cither 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 
different elements of the scale. 
_ The red block of Scioto county becomes the main block of the Ohio 
Valiey. 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 wxathered 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 
