STATE GEOLOGIST. 121 
Per cent. 
WATHON ALE OLIN eR Ee eb t ye genet rece el eceia. is batters) e eres 97.14 
GarbonatemorsmMagn eSiaivecici cog cracie ersonn el sere ears aa eto ekouwis 1.21 
MUIMMI NAVAN deOx CeLOM IRON neers in cierto citielereios Al 
SIATCHOUSWIM ACCS Tacktae cist ahces Soe c crane lok siete rorale tee level conlalausne .70 
99.46 
Occasionally there is found a thin bed of clay, called by Foerste the 
Beavertown marl, overlying the limestone, and at other places a lean de- 
posit of the Clinton ore. The latter furnished the iron for one of the 
pioneer blast furnaces of the state. . 
That the Clinton limestone along its line of outcrop contains petro- 
leum has long been known. This character appears to have been reported 
for the first time by Dr. John Locke in 1838.1. Orton made similar ob- 
servations in 1878, 18867 and 1888.2 Neither of these geologists, how- 
ever, suspected from the surface exposure that the formation might con- 
tain either oil or gas in quantities sufficiently large to be of service to 
man. When the Trenton was being tested at Fremont it was noticed 
that considerable gas escaped from the Clinton, and the former horizon 
proving barren a number of wells were drilled to the latter, the supply of 
gas secured being sufficient usually for one or more residences.* ‘These 
were the first wells drilled anywhere in Ohio for the purpose of securing 
gas from the Clinton. The formation in the northwestern part of the 
state consists of limestone with a small amount of shale. The general 
relations are shown in the following record of a well at Fremont :° 
Feet 
\AV/ER Cent baa We) wee rene rare Ptah 3 ek CR CRS SR eee eA aati Cr 160 
INT aaa es S COME Masectew. tas evsicie ts cok fucuel ologetssighaio ouailepaieueremaiwis 200 
Niagvanas:slialle otis) irc ccistencsbar ckorebesNe-csks) ovsielanciecaeyeoenel's 
CHiNGCOMBIMMESCOM EM s rae cesesss ise Te lone a leie cob ee ee olan oaks 105 
Medina shlail erase rretus ounces wears ra Sec clea uote cots cna terete Tart 105 
Cincinnati (Hudson River) shale................... 450 
WT Cams lvale serra haan OM ONe A iis LUC SRA ei AL “SRR akltienes ei 308 
ELEN TONEMUMESTOMe mate ne taltr cee Meier RU Menai che Abe 1,328 
In central Ohio the formation presents a complete change. The 
limestone has disappeared and there is found in its place a body of shales 
and generally an intercalated bed of sandstone. As shown in the well 
records already given these shales have colors ranging from green to 
brown. They contain a noticeable amount of carbonate of lime which 
becomes most abundant in the 35 feet above the gas rock. The drillings 
strongly indicate that the green and chocolate colored shales are inter- 
1Geol. Sur. of Ohio, Sec. An. Rept. (1838), p. 225. 
2Ibid, Preliminary Rept. on Oil and Gas (1886). 3Ibid, Vol. VI, p. 12. 
4Ibid, Vol. VI, p. 187-8. SIbid, Vol. VI, p. 112. 
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