18. TYRONE TOWNSHIP. F 3 . 375 



The Marcellus limestone, iron ore, and shale, (VIII.) 



The only place where any trace of rhese can be found is 

 at the high knoll opposite Oakgrove furnace, where the 

 black shale and iron ore have been taken out, the latter in 

 considerable quantity. The hill is honeycombed with old 

 workings, and to this day a horse or a man or both will oc- 

 casionally drop in. 



