PICKAWAY COUNTY. 3 591 
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 Taek 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 
overlying 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 large 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. 
Cornijerous Limestone.—This important formation is found in the west- 
ern part of the county. It is the limestone so largely used at Columbus, 
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- 
sliamsport. 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 
