THE MISSISSIPPIAN-PENNSYLVANIAN UNCON- 

 FORMITY AND THE SHARON 

 CONGLOMERATE 1 



G. F. LAMB 



Mount Union College 



There exists in northern Ohio a well-defined boundary between 

 the strata of the Mississippian and Pennsylvanian ages, a boundary 

 marked by a pronounced unconformity. The upper limit of the 

 Mississippian is the top of the well-known Cuyahoga formation, 

 and the lower limit of the Pennsylvanian is the bottom of the 

 equally well-known Sharon conglomerate. 



So far as the writer is aware the Sharon has been generally 

 regarded as a formation of general extent around the northern and 

 northwestern border of the Appalachian coal basin, and resting 

 upon the Mississippian in a continuous sheet except where removed 

 by erosion. 



Field work the past summer in Mahoning, Trumbull, Portage, 

 Summit, and Geauga counties has revealed some facts that lead 

 the writer to believe that the Sharon conglomerate is not the 

 simple formation that it has been thought to be, and that it has a 

 setting of unusual interest. 



Following its outcrop from place to place, the formation is 

 found to change in structure quickly, to disappear suddenly, and 

 to be absent over considerable areas, letting later rocks form the 

 contact with the Cuyahoga. Where its development is greatest, 

 it lies in troughs of the Cuyahoga. Further, it is found to occur 

 in belts having a more or less north-and-south direction, and these 

 belts, in places at least, are not now and never have been connected 

 from east to west. This is due, in part at least, to the fact that the 

 conglomerate lies between ridges of the Cuyahoga, and not alone 

 to post-Pennsylvanian erosion. 



1 Published by permission of Dr. J. A. Bownocker, state geologist of Ohio. Pre- 

 sented at the twentieth meeting of the Ohio Academy of Science, Akron, November 



25, IQIO. 



104 



