644 GEOLOGY OF OHIO. 



in the chapter on Highland county in the Report of 1870, and no further 

 mention of these facts is demanded here. It may be said, in passing, 

 that these quarries furnish in their remarkably even-bedded courses 

 some of the most desirable stones of the State. The fact that all the 

 fragments and. waste of the quarries can be burned into lime of fair 

 quality, renders the working of them as economical as possible. 



But few varieties of fossils are seen in the quarry rock. The bivalve 

 crustacean, Leperditia alta, which is characteristic of the formation, 

 covers thickly the surfaces of many successive layers. A favosite coral 

 is not uncommon, and several species of brachiopod shells are occasion- 

 ally met with. 



Two miles below the Greenfield quarries the rock becomes more fossil- 

 iferous, and well-preserved casts of several species of shells have been 

 found. They are referred to the genera Atrypa, Nucleospira, Meristella, 

 etc. The species are probably undescribed. 



The Helderberg limestone is through all of these exposures — a magne- 

 sian limestone, containing forty to forty-four percent, of carbonate of mag- 

 nesia, and fifty to fifty-four per cent, of carbonate of lime. As the name 

 of the lower member of the group denotes — to which this division, now 

 under consideration, undoubtedly belongs, viz., the waterlime — a cement 

 rock often finds place in the series. The formation is true to its name in 

 Ross county. On the Rittenhouse farm, in Concord township, the upper 

 beds of the series have long been burned into a hydraulic lime of a high 

 degree of excellence. Experience of its qualities for thirty years makes 

 it certain that it is a strong and durable cement. Its composition is 

 given in the report on Highland county, above named. The supply is 

 large, and the cement can be manufactured at advantage in all respects. 

 It requires to be worked, however, in a different manner from the ce- 

 ments in common use, and this fact has hindered the development of the 

 business here. The valuable properties of the stone will doubtless be 

 utilized in time to come. 



The lowest courses exposed in the bed of Paint Creek, at the locality 

 named above, viz., two miles below the railroad crossing at Greenfield, 

 belong, as has been said, to a different horizon, viz., to the Niagara group. 

 They are very readily distinguished, both by lithological characters and 

 by the fossils which they contain. The upper beds of this series in 

 southern Ohio are almost every where characterized by the very conspic- 

 uous casts of one or more of the following fossils, viz., Pentamerus oblongus, 

 Trimerella Ohioensis, Megalomus Canadensis. The casts sometimes make 

 up the very substance of the rock. Other forms are intermingled occa- 

 sionally in great abundance. The more noticeable sorts are favosite 



