712 GEOLOGY OF OHIO. 



whole. For iron making the supply is abundant, and it is found in so 

 many different horizons that it will be difficult to find property on which 

 there is not a full supply. 



On the west, where the ravines cut the base of the Coal Measures, the 

 Maxville limestone is accessible, which, at Webb's Station and Maxville, 

 is eleven feet thick. 



About one hundred and fifty feet below the Great Vein is the Blue 

 limestone, sometimes cherty, but often of good quality, reaching a thick- 

 ness of two and three feet. It is exposed at Shawnee, Straitsyille, and in 

 the valleys to the west and south. 



Associated with the Baird ore, on the horizon of Coal No. 5, is a limestone 

 which in other parts of the State sometimes reaches a thickness of six 

 and ten feet, but seems generally thin in this field. It will probably be 

 found here in places worth quarrying. 



At about forty and seventy feet above the Great Vein are limestones 

 in places five feet thick, frequently ferruginous, and carrying valuable 

 ores. That at seventy feet is the limestone used as a flux in the furnaces 

 at Shawnee, and is rarely wanting in any part of the field. 



The Cambridge limestone is about one hundred and seventy feet above 

 the Great Vein, from two to three feet thick, and of good quality. 



The Ames limestone, two hundred and seventy to two hundred and 

 eighty feet above the Great Vein, is two to three feet thick, and in places 

 in Trimble township, Athens county, is reported by Professor Weethee 

 as fifteen feet thick. Both of these limestones are very persistent, and 

 each will doubtless make a good flux. In the eastern part of Trimble 

 the limestones of the Pittsburgh coal are regularly developed, and are of , 

 good quality. Besides these there is a black limestone three feet thick, 

 seen near Ewing, thirty-seven feet above the Bayley's Run coal, bowlders 

 of which, fallen down from their proper horizon, are often seen through- 

 out the whole territory. There is no doubt that the supply of limestone is 

 ample for all the wants of the smelting furnaces. 



The following table shows the composition of the limestones which 

 have been analyzed : 

 No. 1, Shawnee limestone, by S. B. Newberry : 



Silica 9.91 



Lime 31.19 



Magnesia 12.50 



Alamina and protoxide of iron 3,57 



Oxide of manganese 2.76 



Sulphur -• 0.28 



Phosphorus 0.05 



Carbonic acid 39.35 



Water 0.65 



