PICKA.WAY COUNTY. 591 



ed with the minuter forms of vegetable or animal life. Thus far, search 

 for these forms has been unrewarded. After a failure by myself, I placed 

 samples of the slate in the hands of Prof. Wormley, whose skill in mi- 

 croscopic researches is well known, and whose instruments are of the 

 most perfect kind. Thus far his search for distinct organisms has been 

 unsuccessful. It is reasonable to suppose that the organisms contained 

 no silica or lime, and that in their decomposition and bituminization all 

 organic structure was destroyed. 



The black slate is an evident source of rock oil, or petroleum. It af- 

 fords oil readily by artificial distillation, but we find abundant evidence 

 that it is distilled naturally. At numerous points we find springs of oil 

 at the top of the slate. Generally they are in the lowest layers of the 

 OTerlying Waverly sandstone, as if the ascending oil (for oil, being 

 lighter than water, is upward in its tendency) had been intercepted by 

 the sandstone, and had flowed out between its more open layers. Such 

 oil springs abound in the western part of Scioto and eastern part of 

 Adams counties. In the black slate are often found septaria, or largn cal- 

 careous concretions, which are generally hollow, and contain crystallized 

 calcite, and often shining globules of asphaltum. Near Delaware, and 

 further north, they contain the remains of fishes of the most remarkable 

 size and form. Oil is easily distilled from this black slate, but the yield 

 is not large, and such distillation will be unprofitable while the earth 

 yields petroleum so bountifully. The slate, when burnt and pulverized, 

 is said to answer an excellent purpose for coating for roofs, when mixed 

 with coal tar. Wells bored in the black slate often strike fissures charged 

 with combustible gas, and the gas may be economically used for lighting 

 and warming dwellings and factories. It is so utilized at Painesville, 

 and at other places on the Lake where wells have been bored into the 

 black slate. 



Corniferous Limestone. — This important formation is found in the west- 

 ern part of the county. It is the limestone so largely used at C jlumbus, 

 where it is found on the west side of the Scioto River. The State House, 

 the walls of the Penitentiary, etc., etc., were constructed of this stone. 

 It contains interesting remains of fishes, shells, etc., already described in 

 a previous volume of the Geological Report. In Pickaway county this 

 limestone appears in the bed of Deer Creek, a few miles west of Wil- 

 liamsport. From this point it should be found northward to Columbus, 

 unless buried by Drift and valley deposits. Where the Cincinnati and 

 Muskingum Valley Railroad passes over this formation, on the western 

 edge of the county, the rock is probably covered by superficial materials ; 

 at least I have heard of no quarries of this stone along its line. It 



