250 



The Ohio Journal of Science [Vol. XXI, No. 8, 



In Ohio the steel molding sands are at present all derived 

 from rocks of Pennsylvanian or Carboniferous age. These 

 rocks are subdivided on the basis of their age as follows: 



Pennsylvanian : 



Monongahela formation. 

 Conemaugh formation. 

 Allegheny formation. 

 Potts villa formation. 



At present only the Pottsville and Allegheny formations 

 yield steel molding sand in Ohio, and the Pottsville is much 

 the larger source. 



KENTUCKY 



Map I. 



This shows the outcrop of the Pottsville formation and the location of the plants 

 which produce steel molding sands in Ohio. 



