672 J. A. BOWNOCKER PETROLEUM IN OHIO AND INDIANA 



the time the drill had penetrated 50 feet of the limestone it was useless 

 to continue work. Later^ however, a second and even a third ^^pay" was 

 found, but these have proven of small value in comparison with the first. 



The Trenton limestone in the Ohio part of the field, at any rate, is 

 dolomitic, two analyses showing from 33 to 43 per cent of magnesium 

 carbonate. The rock usually has a dark gray color and, true to its com- 

 position, has a marked porosity. Morever, many samples hurled to the 

 surface in shooting wells contain frequent holes, doubtless due to the 

 solvent action of the contained water. 



The structure of the Trenton limestone in these two States has a 

 marked relation to the production of oil. As has long been known, the 

 Cincinnati axis crosses the Ohio River a short distance east of Cincinnati. 

 Following it northward from that place, it is soon found to bifurcate, 

 one arm running northwest toward the south end of Lake Michigan, and 

 the other one east of north toward the west end of Lake Erie.'^ In other 

 words, the axis forms a Y with the stem crossing the Ohio River near 

 Cincinnati. In Ohio, part of the richest territory has been found on 

 this arch, but in Indiana it does not appear on the summit of the arch, 

 but on the north side, where the rock dips to the northeast. The Tren- 

 ton limestone everywhere in these two States contains an ocean of brine, 

 and this naturally forced the oil to the higher places. 



The "Clinton" Sand Field in Ohio 



This field lies entirely in Ohio and consists of a number of com- 

 paratively small pools that extend from Vinton County on the south to 

 Wayne County on the north. Natural gas was discovered in this rock 

 at Lancaster in 1887, and the drill has extended the reservoir so that it 

 now extends in a disconnected manner from the shore of Lake Erie 

 south almost to the Ohio River. Oil producers argued that where gas 

 existed in such abundance oil must be near, and they at once began the 

 search. Oil in paying quantities was first gotten in this rock in 1899. 

 but no large pools were found until in 1907, when the reservoir in east- 

 ern Fairfield County was located. 



While the producing rock is known as the "Clinton/' it usually lies 

 from 100 to 150 feet below the limestone of that name and appears to 

 form a part of the Medina formation.^ It commonly has a light color, 

 but in places is brick red. The rock is patchy in nature, so that the 

 driller can not be certain of finding the sand when he reaches its position. 



^ Edward Orton : Geol. Survey of Ohio, vol. vi, p. 46. 



E. P. Cubberly : Geol. and Nat. Hist, of Indiana, 18th Ann. Kept., p. 221. 

 8 J. A. Bownocker : Econ. Geol., vol. vi, p. 37. 



