70 Pittsburgh Coal Strata. 



hill," on the north side of the river, fossil Melania and Lymnea, 

 both fresh water shells, were found in a bed of dark carbonaceous 

 clay, under sandstone rock, at "a level many feet below the coal bed. A 

 fossil terrestrial Helix was found in the shale over the coal, changed 

 to sulphuret of iron. Terebratulse, and a small thin shell, probably 

 a Pecten, both marine shells, are also found in the sandstone rock, 

 affording incontestable proofs of the wonderful changes that have ta- 

 ken place in this valley, since the period of the first, or lowest coal 

 deposits. — 20 feet. 



10. Limestone ; light colored, hard and compact ; very few fossil 

 shells are found in the limestone rocks at this place, but at Waynes- 

 burgh and other places farther south they are more abundant.-14 feet. 



11. Great sandstone deposit ; fine grained and compact ; contains 

 but little mica ; color light brown, changing to yellowish ; argilla- 

 ceous. It has many vertical seams from the eighth of an inch to 

 several inches in thickness, filled with carbonate of hme, infiltrated 

 from the limestone rocks above. Where blocks are obtained, solid and 

 free from fissures, it makes a good building stone. This deposit ex- 

 tends to the bed of the river, and is two hundred and seventy feet in 

 thickness. A little below, at the mouth of a small rivulet, several 

 wells have been bored for salt water. At the depth of one hun- 

 dred and thirty feet, after passing through alternations of blue and 

 grey sandstone rock, white, red and blue marl slate, a bed of soft, red 

 marly rock was struck, five feet in thickness, under which was found 

 petroleum, and strong salt water. The bed of red marl reposes on 

 a deposit of coal six feet in thickness. Forty feet below, or at 

 one hundred and eighty feet from the surface, still passing through 

 alternations of sandstone rocks and beds of marly slate, or shale, is a 

 deposit of coal ten feet in thickness, being the two beds noticed in the 

 "sectional view" or "illustration" of the Monongahela river coal 

 deposits. At two hundred and fifteen feet from the surface there is 

 found a tolerable supply of salt water. From all the wells large 

 quantities of carburetted hydrogen gas were discharged, when first 

 sunk, and although several years have since passed away, gas is yet 

 freely afforded. The boring in some of the wells, has been pushed 

 to the depth of more than six hundred feet, and coal found at four 

 hundred and forty, four hundred and eighty, five hundred and eighty 

 and six hundred and sixty two feet, the last only four inches in thick- 

 ness, a proof of the vast depth of the coal measures in the Monon- 

 gahela valley. Coal is abundant in Mercer county, sixty miles north 



