MEDIlSrA COUNTY. 363 



south-east. The glaciated surface is generally covered with a bowlder 

 clay containing many pebbles of crystalline rock, granite, quartz, etc., 

 brought from the far north, and more and larger stones derived from 

 some neighboring region or locality. 



GEOLOGICAL STRUCTUEE. 



A detailed account of the geological structure of the county will follow 

 this introduction, the exposures of rock in each township being described 

 separately. A brief summary only will be given at this point. The 

 general section of the rocks exposed in the county is as follows : 



FEET. 



1. Coal Measures 100 



2. Conglomerate 13.5 



3. Cuyahoga shale (Waverly group) 250 



The Coal Measures reach into the south-eastern corner of the county, 

 and Coal No. 1 is worked with profit in three mines, all in Wadsworth 

 township. This bed of coal also underlies a portion of the south part of 

 Sharon township, these' two townships being the only ones in the county 

 which contain coal. Where mined, the coal reaches a maximum thick- 

 ness of nearly five feet, is of superior quality, containing but little sul- 

 phur. The production of the two principal mines during 1871 was over 

 fifty thousand tons. 



The Carboniferous Conglomerate is exposed in seven townships, all in 

 the two easterif tiers excepting Guilford. But most of this conglomerate 

 region shows the Cuyahoga shale of the Waverly group in the deeper 

 ravines ; in fact, the prevailing rock in Medina county is of this older 

 division. Some fair building stone is quarried from the Conglomerate, 

 but a great portion of this rock is unfit for building purposes. The 

 character of the Conglomerate varies materially in the several places 

 where exposed. In general the pebbles contained in it are quite small, 

 and compose no considerable part of the formation, sand constituting 

 the bulk of the material. The estimated thickness of the Conglomerate 

 in Medina county is one hundred and thirty feet. 



The Waverly series, or the upper division of it, now named Cuyahoga 

 shale, is the third and oldest group of rocks found in Medina county, 

 the greater portion of the Drift being immediately underlain by the 

 Cuyahoga shale, which is exposed in a majority of the townships. 

 Roughly estimated, the Cuyahoga shale in Medina county may be said 

 to have a thickness of two hundred and fifty to three hundred feet. 



This formation is exceedingly rich in fossils, some of the characteristic 

 species being Hemipronites crenistria, Productella Newherryi, Sanguinolites 



