230 GEOLOGY OF OHIO. 



textured, often carious, yet when compact is crystalline. It is in thin 

 beds of about three inches, more or less lenticular, making it easy to 

 quarry and to get into fragments of suitable size. Yet it also sometimes 

 has a brecciated or concretionary structure, when large pieces of irregu- 

 lar shape, often cavernous and easily broken, are taken out. It has a 

 light buff color, and is sometimes white. When freshly quarried it may 

 be spotted and variously marked with purple, especially when taken 

 from the deeper parts of the quarry. The rough and vesicular condition . 

 may be seen in Woodbury's quarry, also in Mr. Holt's ; the more even- 

 bedded in William Habbeler's. Fossils collected at Genoa have been 

 forwarded to the Palaeontologist of the Survey, and the reader is referred 

 to his report for names and descriptions. 



The Salina shale immediately overlies the Niagara in Ottawa county. 

 Along the north shore of Sandusky Bay, in the township of Portage, it is 

 an earthy, dove-colored limestone, in beds of two to four inches, which, 

 exposed to the weather, becomes quite blue ; and being permeated with 

 gypsum in small, detached masses, it often crumbles. Some of the beds 

 are more enduring, and are, in that case, more brown than blue, weath- 

 ering a chocolate. The bedding is quite loose, as if some profound dis- 

 turbance had shattered the layers. At the Plaster Beds, owned by Mr. 

 George A. Marsh, of Sandusky, the Salina 'is exposed to the depth of 

 thirty feet in quarries which have been opened for gypsum.* Although 

 the geological relation of the rock containing the gypsum cannot be ascer- 

 tained by examining outcrops within Ottawa county, it is believed to 

 hold a place within the Salina, since neither the Niagara nor the Water- 

 lime is known to afford this mineral in workable quantities in other 

 parts of the country ; yet the lithological features of the rock containing 

 it are very similar to those of the Waterlime seen in Wyandot and Allen 

 counties. Although it here has a thickness of at least thirty feet, at 

 Genoa it is reduced to less than a foot, and is seen in the form of a green 

 shale, which also, on weathering, turns blue and falls to pieces. It is 

 best seen at the bottom of the quarry of Messrs. Newman and Ford, but 

 'is penetrated also in Wyman and Gregg's. 



Over the Salina shale the Waterlime is found. This has three distinct 

 lithological characters within the limits of the county. It most fre- 

 quently occurs — 



1st. As a coarse brecciated, gray, or drab- gray, limestone, with rough, 

 cavernous surfaces, indistinct bedding, or massive, with no fossils. It 



* About 10,000 tons of gypsum are taken per annum from these quarries. It is 

 of excellent quality, and is widely sold throughout the western States. 



