and count this element as but one of the many alternations in color that are found for many hundred feet in this part of the section.

116. The Berea Grit.

We have reached in our review the Berea grit, the second element of the Waverly series, and not only the most important member of the series, but by far the most important single stratum in the entire geological column of Ohio. Its economic value above ground is great, but it is greater below. In its outcrops it is a source of the finest building stone and the best grindstone grit of the country, and when it dips beneath the surface it becomes the repository of invaluable supplies of petroleum, gas and salt-water. Its persistence as a stratum is phenomenal. Seldom reaching a thickness of fifty feet, its proved area in Ohio above ground and below, is scarcely less than 15,000 square miles, and beyond the boundaries of Ohio it extends with continuity and strength unbroken into at least four other adjacent states. As a guide to the interpretation of our series, and especially as a guide in our subterranean geology, it is invaluable.

The stratum was named by Newberry from the village of Berea, Cuyahoga county, where the largest and most important quarries of the formation are located. The name is the most appropriate that could have been selected for this stratum, and inasmuch as it has priority in all fields, it ought to be made to supersede all others.

From what has already been stated, it will be seen that the Berea grit and the Waverly quarry-stone of southern Ohio are one and the same sheet of sandstone. This identity was missed for a long while in the study of our geology, and a wrong order of arrangement found temporary acceptance. The resulting dislocation of our Subcarboniferous series brought into all our work upon it an element of confusion that is scarcely yet eliminated.

The Berea grit, as seen in outcrop, is a sandstone of medium grain in northern Ohio and of fine grain, from the center of the state southward. In northern Ohio, it contains one pebbly horizon over a considerable area, but the seam is thin and the pebbles are small. The stratum is sometimes false-bedded and sometimes remarkably even in its bedding-planes. Its main beds, or sheets, have a maximum thickness of six feet, but this is an unusual measure and is seldom reached. It ranges in thickness from 5 to 170 feet, and it very rarely fails altogether from the sections in which it is due.

Like the Bedford shale below it, it stands for an old shore-line, many of its surfaces being ripple-marked and worm-burrows abounding in its substance.

It is pcor in fossils, but not entirely destitute of them. Several species of Lingula have been found in it, and a few lamellibranch shells also. Fishremains are the most conspicuous, but by far the rarest of the forms that it contains. Plant impressions are also unusual through most of the formation, but in northeastern Ohio there is a certain part of the stratum in which they are quite abundant. Throughout the great quarry district the material of which the stratum is composed is as clean sand as can be found on any sea beach. It grows more impure as its sand grows finer in grain in central, and especially in southern Ohio. A small percentage of clay is held in it at most points.

Under cover, it retains the same characteristics as to composition that it possesses above ground, ranging from fine to middling grain and very seldom showing pebbles. It has been proved by many hundred borings in southeastern Ohio during the last few years, and its composition there is almost as well known as in its outcrops.

11c. The Berea Shale-Waverly Black Shale of Andrews.

A bed of dark, often black shale, fifteen to fifty feet in thickness, makes the constant and immediate cover of the Berea grit throughout its entire extent in Ohio. The shale is highly fossiliferous. It contains Lingula melie and Discina Newberryi, almost everywhere, and at many points it is crowded with fish-remains, becoming, in fact, a true bonebed. Species of Cladodus, Orodus and Ctenacanthus have been already described from it. Conodonts are very abundant in it. The bottom layer, which is especially rich in fossils, is very hard and stubborn, being composed of sand bound together with pyrites. It is often referred to the sandstone below rather than to the shale above, but its fossils and its bituminous character favor the reference here given, inasmuch as it marks new conditions in the history of these beds.

The stratum was first described by Andrews under the name of the Waverly black shale, the typical outcrop being found at Rockport, on the Ohio River, but about the same time Meek, who was studying its fossils in northern Ohio, introduced the designation Berea shale. (Pal., Vol. II, Plate XIV.) The latter name is clearly preferable and ought to obtain currency.

Its southern outcrops were mistaken by Newberry for the Cleveland shale, and the fossils found in it were credited to the latter stratum, and thus a good deal of confusion prevails in the published statements upon this part of the Waverly series.

In southern and central Ohio, and indeed in almost all of its outcrops, the boundaries of the Berea shale are sharp and perfectly distinct.

The Berea grit is its base, and the blue beds of the Cuyahoga shale overlie it. In Cuyahoga county, however, and eastward, the upper limit cannot always be fixed with precision, neither the dark-color nor the fossils of the shale disappearing abruptly, but both gradually diminishing. There are, however, twenty to forty feet that always deserve to be counted here.

When struck by the drill under cover the formation yields uniformly a similar line of facts to that already reported. Of the records of the many hundred wells that have been carried down to and below this horizon in southern Ohio and in adjacent territory during the last few years, there has not a single one been found that has failed to give a place to this little band of black shale. Its services in setting in order our Subcarboniferous geology have been simply invaluable. It is wanting at a few points in northern central Ohio apparently.

The Berea shale contains a larger percentage of bituminous matter than the Ohio shale, the amount sometimes reaching 24 per cent. It is a source of petroleum on a small scale, as is shown by the fact that in southern Ohio an important ledge of sandstone that belongs just above it is often found saturated with a tar-like oil, derived from this source.

11d. The Cuyahoga Shale.

It is impossible to retain for this great division of the Waverly the limits assigned to it by Newberry when he gave it its name. He made it fill the entire interval between the Berea grit and the Coal Measure conglomerate, and according to present knowledge, at least three distinct elements are to be found in every normal section of this interval. One of them has already been described, viz., the Berea shale, cut off from the foot of the column. Another, and a much more conspicuous element must be taken off from the top of the column, viz., the Logan group. But there still remain 150 to 400 feet of a perfectly distinct, homogeneous and most persistent formation that deserves a name as much as the Berea grit itself, or any other stratum in the Ohio scale, and for which no more suitable name could be found than that which it already bears, viz., Cuyahoga shale.

It consists of light-colored, argillaceous shales, which are often replaced with single courses of fine-grained sandstone, blue in color, and in southern Ohio weathering to a brownish-yellow. As a constant characteristic, there are found through the shales, flattened nodules of impure iron ore, concretionary in origin, and often having white calcareous centers.

By good rights the shale should suffer one more reduction at its

lower extremity. Everywhere through the state there is found directly above the Berea shale, or at a short remove from it, a number of courses of fine-grained stone. These courses are sometimes separated from each other by beds of shale, or they may be compacted into a single stratum. The individual courses also vary greatly in thickness, and in color and general characters. Throughout southern Ohio, and particularly in Ross, Pike and Scioto counties, the stratum yields freestone. It is best known from its outcrops on the Ohio river at Buena Vista, where it has long been very extensively worked for Cincinnati and other river markets. The Buena Vista stone, at its best, is one of the finest building stones of the country. The same horizon yields excellent stone near Portsmouth, Lucasville and Waverly. It is known as the Waverly brown stone at the latter point.

Northward, through the state, stone of more or less value is found in the bottom courses of the Cuyahoga, but in Trumbull county, near Warren, the horizon acquires extreme importance as the source of the finest natural flagging that is found in our markets.

It would have been well if the thirty or forty feet containing these courses had been cut off from the Cuyahoga shale, in which case the division thus formed would have been well named the Buena Vista stone, but inasmuch as the series does not absolutely require the change, it is left unmodified. As will be presently shown, the Sharpsville sandstone of White (Second Penna. Survey), belongs to this horizon, and is the proper equivalent of the Buena Vista stone.

There are a few sections in which the Cuyahoga shale is more largely replaced by these freestone layers than in the general account above given. In the cuts of the Marietta and Cincinnati Railroad, east from Chillicothe, the freestone appears to constitute a notable percentage, perhaps fifteen or twenty, of the whole material. There are other points at which the stone has no value.

Under cover the Cuyahoga shale retains with great distinctness and persistency the same characteristics that are found in its outcrops. From the deep drillings of eastern Ohio, wherever its horizon has been reached, there are uniformly reported 300 to 400 feet of white shales with occasional sandstone layers, through which the drill descends rapidly and easily. The Buena Vista courses are also frequently reported directly above, or at least near to, the Berea shale.

The fossils with which the Cuyahoga shale has been credited have been largely derived from the division next to be described, while this was counted a part of the shale. As here limited, it is, for most part, very poor in fossils. The surfaces of many of its beds are marked with

the impressions of the cock-tail fucoid, and in its upper portions occasional courses are found in which the animal fossils of this age are abundant and well-preserved.

11e. The Logan Group.

(The Olive Shales of Read. The Logan Sandstone of Andrews. The Waverly Conglomerate of Andrews).

The divisions of the Waverly series in northern Ohio happened to be made at a point where the section is abnormal and incomplete. By atrophy or by overlap, the upper member of the series is wanting in the Cuyahoga Valley, or is at least very inadequately represented there. The missing member is in volume second only to the Cuyahoga shale, among the divisions of the Waverly. It is much richer in the fossils of the Subcarboniferous than any of the other members. In composition it is varied and striking, one of its elements being a massive conglomerate not less than 200 feet in its largest sections, which extends in unbroken outcrop through at least a dozen counties of Ohio. No good reason can be found for dividing the Waverly series at all, if a member like this is to be left without a name, or is to be merged with an unlike and incongruous division from which it is as sharply differentiated as any one stratum of Ohio is from any other.

The real, though not the formal, separation of this group from the underlying shale, is due to the late Professor E. B. Andrews, and constitutes one of his most important contributions to our knowledge of Ohio geology. He was the first to show that the great conglomerate of Hocking, Fairfield and Licking counties is Subcarboniferous in age, and he further called attention to a highly fossiliferous, fine-grained sandstone overlying the conglomerate, to which he gave the name of Logan sandstone, from its occurrence at Logan, Hocking county. Up to this time this conglomerate had been universally counted as the Coal Measure conglomerate. Read made known the existence of a heavy body of shale, which he called Olive shales, overlying the conglomerate and replacing the Logan sandstone in Knox, Holmes and Richland

counties.

As both conglomerate and sandstone have their typical outcrops at Logan, no better name can be found for the formation which must include conglomerate, sandstone, and shale, than that here adopted, viz., Logan group.

The maximum thickness of the Logan group is not less than 400 feet. Its average thickness is perhaps 200 feet. It has received less study than the rest of the series, and much work is needed in the