Trenton (?) limestone.-Because of the importance as a source of gas and oil in western Ohio of the Ordovician limestone that is commonly called Trenton limestone two wells have been drilled to that formation in the Cleveland district. They were both put down in the eastern part of Cleveland, and both were unsuccessful. One was drilled by the Park Drop Forge Co. at East Seventy-ninth Street and the New York Central Railroad, and the other by the Cleveland Twist Drill Co. at Lakeside Avenue and East Forty-ninth Street. In the latter well a small flow of gas was found in the so-called Trenton, and the highest rock pressure observed was only 37 pounds to the square inch. An analysis of this gas, furnished by Mr. J. V. Emmons, follows:

Analysis of natural gas from Trenton (?) limestone at Cleveland

A condensed record from this well, in which the top of the Trenton (?) limestone was reached at 4,445 feet, follows:

Partial record of well of Cleveland Twist Drill Co., Lakeside Avenue and East Fortyninth Street, Cleveland

Pressures. The largest authentic rock pressure reported in the Cleveland district was in a well of the National Carbon Co., which registered 1,120 pounds to the square inch. One of 1,250 pounds was reported, but it was probably not authentic. The usual initial pressure for wells in the Lakewood area was about 1,100 pounds. In the West Park area the initial pressures were about 1,000 pounds. The Stadler well decreased from 950 to 100 pounds during its period of service of about a year and a half.

PETROLEUM

Although there are vast amounts of petroleum in the Devonian shales, it is disseminated through them in such small quantities that it is not obtainable economically. At many places in the district are so-called oil springs. The "Euclid bluestone" at some localities contains a little oil, which comes to the surface along cracks and bedding planes. The oil, however, probably originates in the shales immediately underneath. The Mills well, cited in the discussion of rock gas (p. 117), showed oil at 2,200 feet, at a position in the Niagara limestone of the Big lime. This is probably the horizon of the Newburg sand. Several wells that were drilled and abandoned by the East Ohio Gas Co. in 1907 and 1908 were left uncapped, and oil either flows out at the top or can be obtained at a depth of a few feet, where it probably floats on water. During the gas boom, in 1914 and 1915, about 30 wells are reported to have found showings of oil. Two of these wells found oil in the Stray sand at a depth of about 1,400 feet, four in the Newburg sand, and the remainder in the Clinton sand. Several wells were reported to flow 30 to 40 barrels daily, some before and some after shooting, but most wells came in at 10 to 20 barrels, and practically all were short lived. Most of the wells of the Cleveland field after producing a few barrels for a month or so have ceased pumping. It is therefore evident that any hope of an oil boom in the Cleveland district was disappointed. Probably the best oil well is that of the Newburg Brick & Clay Co., which was the real pioneer of the district. (See p. 117.) This gas and oil well came in on October 17, 1911, with a natural flow of 35 to 40 barrels. After it was shot it produced 100 barrels. daily for a time. The oil was struck at a depth of 2,520 feet in the Newburg sand; it is said to contain little gasoline.

The results of three distillation tests, made by the National Refining Co., of crude oil from the Cleveland district, all of which probably came from the Clinton sand, are given below.

Distillation test of 16,000 cubic centimeters of crude oil, with a gravity of 41.2° Baumé, from Lakewood

This crude oil contains a large percentage of high-grade waterwhite oil, which can be refined for market without the use of lead. The percentage of sulphur is very low.

Distillation test of 11,000 cubic centimeters from a 3-gallon sample of crude oil having a gravity of 41.1° Baumé, from West Park

Distillation test of 16,000 cubic centimeters of crude oil having a gravity of 42.2°

Baumé, from Cleveland

EFFECT OF STRUCTURE AND OF PHYSICAL CHARACTER OF THE SAND ON

ACCUMULATION OF OIL AND GAS

In general the accumulation of shale gas in the vicinity of Cleveland is only slightly if at all affected by underground structure. Small terraces and local anticlines in the shales have long been known, and Orton 19 has mentioned one place where an arching of the shales along an axis trending N. 40° E. has possibly caused an accumulation of gas. The Mastick well, mentioned in the discussion of shale gas, was driven on the apex of this fold, but as the fold is believed to have resulted from only a surface disturbance, its influence on the accumulation of gas at depth is considered slight. In general, it is believed that these structural features have little if any relation to the occurrence of shale gas in the district as a whole. The factors in the accumulation of oil and gas in the sands of the Cleveland gas field are discussed as follows by Rogers: 20

In attempting to find extensions of the Cleveland field or new pools in this region a knowledge of the factors that have influenced the accumulation of the gas is very desirable. It is a common belief, especially among oil and gas operators in northern Ohio, that geologic structure has had little to do with the position of pools in the Clinton sand and that variation in the porosity of the sand itself is the controlling factor. On the other hand, it is held by many that accumulations in the Clinton are controlled by terrace structure or by minor undulations in the monoclinal slope, and it has recently been shown that the pools near

19 Orton, Edward, Ohio Geol. Survey, vol. 6, p. 432, 1888.

30 Rogers, G. S., The Cleveland gas field, Cuyahoga County, Ohio, with a study of rock pressure: U. S. Geol. Survey Bull. 661, pp. 27-30, map, 1918.

Wooster, 50 miles south of Cleveland, are closely associated with small anticlines.21 If in the Cleveland region the texture of the sand is the controlling factor, a large number of dry holes must be expected in efforts to discover extensions of the field; but if structural conditions have played an important part, prospecting may be conducted more intelligently.

The Clinton sand is exceptional among important oil and gas reservoirs in that it does not crop out in the vicinity of its productive area. It rises from a great depth beneath the Appalachian coal basin, becomes somewhat thinner toward the west, and feathers out in central Ohio, where it approaches nearest the surface. The tendency of gas to migrate up the rise is generally considered the ultimate cause of its accumulation near Cleveland as well as in the great belt to the south, for it is in this general zone that its upward migration is stopped by the thinning out of the sand. The sand does not disappear completely along a single regular line; there is a border zone in which it is present only in small irregular areas, some of which, like that at Oberlin, may prove productive. As the logs of a number of wells a short distance west of the Cleveland field report the sand as absent, the field appears to be on the eastern edge of the zone in which the sand is irregular.

Although the feathering out of the sand has determined the general position of the great Clinton gas fields, structural conditions have undoubtedly operated to localize the accumulations. In many of the southern fields and as far north as Wooster the gas is not accumulated directly at the edge of the sand but has been trapped in structural irregularities a short distance below. In the writer's opinion structural conditions have also controlled the accumulation of gas near Cleveland. The field as now developed is confined entirely to a very gentle structural nose or bulge; most of the oil occurs below the gas and approximately at one structural level, and below this level the sand appears to be practically barren of either oil or gas. Aside from this local structure, the marked change in the strike of the Clinton, forming an elbow or pocket near Cleveland, has probably also furthered the accumulation of gas in this locality. [See pl. 19.]

A third condition affecting the accumulation of the gas is variation in the porosity of the sand, and this factor seems to have controlled very largely the detailed outline of the productive area and the position of the richer territory within it. In fact, the outline of the productive area is so irregular that at first sight it appears to have little relation to geologic structure. For example, the narrow and sharply defined strip of barren territory separating the West Park and Lakewood pools and extending at right angles to the strike can not be explained on structural grounds, nor can the irregular barren area on the minor structural terrace in the central part of Middleburg Township. These local variations must be attributed to the character of the sand, and it is only when the field is viewed broadly that the true significance of the structure becomes apparent. As accumulations of gas in areas near by have probably formed under conditions similar to those in the Cleveland field, the foregoing conclusions furnish several suggestions for prospecting. It is evident, in the first place, that the Cleveland field is near the western limit of the general productive belt and that the sand becomes irregular and discontinuous to the west. Productive areas may be discovered west of the Cleveland field, but such areas are likely to be small, and prospecting for them will probably involve a number of dry holes. The zone in which the sand dies out trends somewhat west of south, however, and as prospecting continues south it may therefore be extended farther west. The eastern limit of the general productive belt can not now be determined.

" Bonine, C. A., Anticlines in the Clinton sand near Wooster, Wayne County, Ohio: U. S. Geol. Survey Bull. 621, pp. 87-98, 1916.

Although in the Cleveland field the territory below the 1,000-foot contour seems to be practically barren, farther south productive areas have been found at lower levels, correspondingly farther from the thin edge of the sand. The pools near Wooster, for example, extend at least as far down the dip as the 600-foot contour (2,400 feet below sea level). Furthermore, as the strike of the Clinton turns to the east near Cleveland, the sand may be found along the lake shore to the northeast at depths of 2,000 to 2,400 feet below sea level. This area has not been seriously tested, and although such results as have been attained are chiefly negative the district should not be condemned without further exploration. Southeast of the Cleveland field the depth of the Clinton sand increases rather rapidly, and prospecting can not extend many miles in that direction.

The most favorable localities for prospecting within the area just outlined are those in which the dip of the Clinton changes in degree, and the larger accumulations of gas will probably be found in the structural irregularities so formed. The pools near Wooster are closely related to rather sharp anticlines; in the Cleveland district the structure is more gentle, but the field as a whole is confined to a broad nose. As the southern edge of this nose seems to be at Berea, the development on this particular structural feature may be regarded as already well outlined. Little is known of the detailed structure between Berea and Wooster, but it is highly probable that other noses, anticlines, or terraces exist. A sufficient number of wells have already been drilled in certain parts of this district to make possible a general comparison of the altitude of the sand at different points, and a study of this kind, supplemented if possible by an examination of the surface geology, would doubtless prove a valuable aid in prospecting. In the district east and northeast of Cleveland nothing is known of the detailed structure, and prospecting offers less chance of quick returns than in the area to the south.

Although structural conditions undoubtedly control the general position of the pools, it should be borne in mind that the character of the sand itself determines their detailed outline. One or two unsuccessful wells in an area of favorable structure do not necessarily condemn it; several of the earliest wells in the Cleveland field, put down close to what has proved highly productive territory, were dry. As a general rule the more pronounced the structure the more closely is the distribution of the gas related to it; where the structure is broad and gentle, as in the Cleveland field, the character of the sand becomes a more important factor.

SAND AND GRAVEL

The large population of the district requires a great amount of sand and gravel for many purposes, the chief uses being for making mortar and concrete. Other uses are for gravel roofs, railroad ballast, and surfacing roads and walks. Minor uses are for molding in foundries, in sanding molds for soft mud brick, and as an abrasive for sawing stone. The sand and gravel of the district are composed of fine and coarse particles of quartz, feldspar, garnet, and magnetite, as well as pieces of granite, diorite, anorthosite, granitic gneiss, various schists, quartzite, and limestone. Some of it may have originated in each of four ways, and consequently four kinds of sand or gravel may be distinguished-glacial, lake, river, and artificial. The largest deposits in the district are of glacial origin and are found along the electric railroad connecting Akron, Bedford, and Cleveland and along the Pennsylvania Railroad near Garfield Park, where they