the shale formation. The drill rested in black shale at the bottom of the hole.

(3) Numerous wells drilled at New Lisbon show a similar state of facts. The driller's record of one drilled in the fall of 1886 is as follows:

The last element is the Ohio shale, re-enforced by the Bedford at the summit of the series. The white and blue sand-rock directly above are the Berea grit, here yielding quite a flow of gas and also salt-water. The Cuyahoga and Berea shales are included in the 245 feet next above, while the Logan or salt-water sand is found in the seventy feet of white sand of the record. The level of the upper surface of the Berea grit is about 323 feet above tide at this point.

(4) The wells of East Liverpool and vicinity furnish the next section. The number of these wells is large, and their records all agree as to the essential features of the section. The record of a well drilled in 1885 at Dry Run, a few miles above Liverpool, will indicate the usual order of facts. It is as follows:

The shale below the Berea grit has been deeply and thoroughly explored here also by the drill, but with not quite the same negative results as reported at the last station, so far as sandstones are concerned. One well was carried 2,500 feet below the Berea grit without exhausting the shale formation, and two or three sandstones were reported in the column. The level of the Berea grit at East Liverpool is about 240 feet above tide. From East Liverpool to Steubenville there is a much more rapid descent of the strata than has thus far been found. In the interval of twenty-four miles the dip of the basal measures is not less than 800 feet, which throws the Berea grit at Steubenville to 560 feet below tide. The Lower Coal Measures, Conglomerate and Carboniferous limestone formations, make 540 feet in the well record here; the Logan group, 265 feet; and the Cuyahoga shale, including the Berea shale, 365 feet. The Berea grit is often reduced to small dimensions, but it maintains its place with surprising constancy. It appears here as a white sandstone, oil or gas-bearing, from five to fifteen feet in thickness. The shales have been penetrated 1,000 feet below the Berea grit at Steubenville without revealing any sandstone stratum of considerable volume. At Brilliant, ten miles below Steubenville, and especially at Wellsburgh, on the opposite side of the river, a large production of gas has been obtained from the Berea grit within the last few years. The stratum is found in a normal and unmistakable section. Its surface lies 607 feet below tide.

D. A fourth radial line of sections will be traced from Shelby through Mansfield, the Neff gas-wells, Coshocton, Cambridge and Quaker City. It follows a southeast course. A part of these stations have already been described. At Shelby the Berea grit lies 940 feet above tide, and at Mansfield 640 feet. This line of sections is marked D on the map of the Berea grit.

(1) At the Neff gas-wells, which are located in the valley of the Kokosing on the east side of Knox county, near the northeast corner of Coshocton, a valuable series of facts has been obtained from seven wells drilled in the immediate vicinity, within the last twenty years.

The records all agree in their essential features. The wells are begun in the Logan group, or the Waverly conglomerate system, and find the Berea at a depth of about 600 feet. Underneath the Berea grit a chocolate-colored band of the Bedford shale occurs as the most characteristic mark. The Waverly group is considerably thicker in this region than in other parts of the state. The series penetrated appears to be divided in the way indicated below, viz.:

Below the Bedford shale the blue and black beds of the Ohio shale are found in their usual alternation for many hundreds of feet. The Berea grit in these wells (Nos. 1 and 2) is about 235 feet above tide.

(2) A well drilled 2,108 feet deep in Coshocton, in June, 1886, furnishes the following record :

The Berea grit is here found at 861 feet by the record given. By another record, it was found at 840 feet. This shows it to be seventy or ninety feet below the sea. The well was drilled by Macksburg drillers who were entirely familiar with the general section, and who were at no loss in positively identifying all of the main elements with the like elements in their own field.

The section at Cambridge, which is the next station in line D, has been already given. The Berea grit is here 175 feet below tide.

Quaker City lies a little to the north of our line, but the section obtained here can be introduced without violence at this point. A well drilled in 1886 furnished the following section:

Barren Coal Measures, Lower Coal Measures, and Conglomerate
Measures

Water sand, Logan group.................

Gray shale, Cuyahoga shale....

Black shale, Berea shale......

Macksburgh sand, Berea grit, at a depth of 1,346 feet.........

This completes the several lines of sections that were undertaken for the purpose of showing the continuity of the Berea grit throughout eastern Ohio. It is hard to see what better demonstration of this continuity could be asked than such sections furnish. Much additional testimony will, however, be found in the detailed statements of sections that are to follow. In the accompanying map, the areas in which the Berea grit lies above sea-level are distinguished from those in which it lies below, the boundary passing through Columbiana, Carroll, Tuscarawas, Coshocton, Muskingum, Perry, Hocking, Vinton, Jackson and Scioto. The entire area occupied by the formation is not less than 20,000 square miles.

II. PRODUCTION OF OIL AND GAS.
A. SOURCE OF THE SUPPLY.

The Berea grit is a representative oil-rock. The presumption in regard to it in any portion of the state in which it lies below the surface is that oil, gas, or salt-water, one or two or all, will be found in it in appreciable amount when it is reached by the drill. In a field of a few square miles it has been found to contain so large a stock of oil that its production for a year exceeded 2,500 barrels per day, and at many points a small production has been established from it; in several fields it has been found charged with high-pressure gas, and at very many points with low-pressure gas; in others it has been a productive source of brine for the manufacture of salt, and also of bromine, and generally in connection with more or less vigorous supplies of natural gas.

Its oil is not indigenous. There are but few beds of clearer or cleaner sand in our geological scale than this. It would be absurd to suppose that the great petroleum stocks of the Macksburg field have their origin in ten or twelve feet of clean sand which contain the oil. The source of occurrence of oil at Mecca is also decisive as to this point. The Berea grit is here covered only with bowlder clay, so far as much of the productive territory is concerned. It thus appears that the natural shale cover of the sand was all eroded in distant ages. Before this took place the stratum must have been charged with oil. While lying exposed as a surface rock, oil must have continually oozed from it, as we find oil and gas escaping from certain outcrops now, but when the nearly impervious beds of bowlder clay had once more formed a cover the accumulation of oil was resumed in the rock, and thus the somewhat scanty stocks that have been drawn up for the last twenty-five years have originated.

The source of the oil of the Berea grit is not doubtful or problematical, it is obvious and demonstrable. The oil is derived from the great shale series which underlies the sandstone, and is simply stored in the latter as a reservoir. The shales are an adequate source, and they are directly at hand. They contain free petroleum through their whole extent. Some storage is effected in the shales themselves. The hard bands are often found, as the drill descends through them, to hold some small accumulation of either oil or gas, but the great accumulations pertaining to them are, in all cases, effected by sandstones or conglomerates that are buried in the shales. The Berea grit, being the only regular sandstone contained in the Ohio shales within the limits of the state, becomes, as has been noted, a universal source of these bituminous products.

The conditions for these accumulations, so far as source is concerned, are absolutely univeral throughout the territory occupied by the Berea grit. There is everywhere underlying the Berea grit an abundant source of oil and gas. A second condition, which, like the first, is indispensable to oil accumulation, viz., an impervious cover to the oil-rock, is found wherever the Berea grit has its normal roof, viz., the Berea and Cuyahoga shales, but it has this normal roof wherever it lies deep enough to retain it. This condition also is complied with to a large extent throughout the territory in question. A third requisite for oil and gas accumulation, the Berea grit itself meets. As has been already shown, it constitutes a reservoir for both substances. It cannot, however, be claimed that it meets this requisite as effectively and as constantly as the two series of shales that serve respectively as source and as cover meet the conditions imposed on them. It is, doubtless, too finegrained and too close in parts of its extent to make a good oil-rock. Its thickness is also, in many instances, too small to afford large storage. But still it is true that so far as can be seen, this condition of a reservoir is also fulfilled on a very large scale in the territory under consideration, and we can, accordingly, declare that the three principal requisites and conditions ordinarily laid down for petroleum accumulation occur throughout a large portion of eastern Ohio.

But, although these conditions are present, the stocks of oil that become valuable to us have not been gathered, except at a very few points. It is obvious, therefore, that there is some other essential requisite for large production. This requisite we find in peculiarities of geological structure. There is a small accumulation in the Berea grit almost everywhere, by virtue of its relation to the shales that respectively support it and make its roof, but the oil and gas-fields that deserve the name seem to be characterized in all instances by departures from the regularity of structure which belongs to eastern Ohio generally. The best example of this abnormal structure comes from the most important field of oil production from the Berea grit, viz., Macksburg.

In the vicinity of Macksburg, north of Marietta, the light southeastward dip of the strata is found to be interrupted, and for nearly a mile a terrace-like structure prevails. This is masked, it is true, by the immense erosion which the country has suffered, and only comes into view when the best-known elements of the exposed section as coal-seams are followed by means of the level. All of the strata ever reached by the drill, as well as all that are above the surface, are equally affected by this structural irregularity.

But this terrace is an oil-field, and has been for twenty years. Oil was first found here in shallow wells, from two hundred to three hun