THE BEREA GRIT OF OHIO. By EDWARD ORTON, of Columbus, Ohio.

THE geological place of the Waverly group of Ohio is no longer a disputed question. It has been proved to be of Sub-carboniferous age so far at least as the bulk of the strata, included within its generally received limits, is concerned. Some confusion, however, still exists in regard to its boundaries and subdivisions and as to the range and extension of the series through the state and into adjacent territory.

Within the last two or three years, I have spent such time as I could control in studying this series as it is shown in Ohio, and within this period I have for the first time obtained, in regard to its leading elements at least, a clear and self-consistent view. The construction that I have been led to give to the facts differs in some details from that which has heretofore been made public. I wish to bring before the Association a few results that I consider fully established as to this series, and which seem to me indispensable to a correct interpretation of this important division of our geological scale.

The Waverly group derives its name from the town of Waverly in the lower Scioto valley. A ledge of valuable building stone that occurs at this point, and below it in the valley, began to find its way to the central portions of the state more than fifty years ago, under the name of the Waverly sandstone. The name Waverly was gradually extended to the shales below the sandstone and to the shales and sandstones above, until the whole series between the great black shale that crosses the state from north to south, and the Carboniferous conglomerate or the lowest Coal Measure rocks came to be included in a Waverly group.

Questions as to age, equivalence and continuity soon arose and decided differences of opinion were developed among the geologists who were dealing with the series in whole or in part.

In considerable portions of the group, and this too in the lower and more critical portions, but few fossils had been found, and the stratigraphical connections were obscure and uncertain. A great advance was made towards a true order when, about ten years since, Dr. Newberry announced the discovery of Chemung fossils in the upper portion of the Erie shale of northern Ohio, and of

fossils of distinctly Carboniferous type in the Cleveland shale of the same district. At the boundary between these two well characterized strata, he fixed the line of division for the Ohio scale, between Devonian and Carboniferous time.

To give this statement its proper significance it is necessary to review briefly the geological sequence of a part of the strata of northern Ohio and the classification made of them by Dr. Newberry.

A stratum of black shale, ranging from 150 to 350 feet in thickness, above the Corniferous limestone, but separated from it by ten to thirty feet of blue or calcareous shale, was named by Newberry the Huron shale, a designation adopted from Dr. Alexander Winchell's classification of the Michigan series. This black or Huron shale is almost entirely destitute of animal fossils through the greater portion of its extent, but the calcareous shale at its base is sometimes highly charged with fossils, the fossils being, according to Newberry, exclusively of Hamilton age. This thin and somewhat uncertain stratum is counted by the same geologist as the true and only representative of the Hamilton group in Ohio. I believe this stratum to be the same which Professor N. H. Winchell has named the Olentangy shale in central Ohio, where however it is very poor in fossils.

The Huron shale was further described as covered in northern Ohio by the Erie shale, a mass of blue shale that has a thickness of 100 feet or thereabouts in Cuyahoga county, and rapidly increases in thickness to the eastward, so that 1000 or even 1200 feet are claimed for it on the Pennsylvania line. It was in the upper portions of this Erie shale that the fossils were found which were clearly of Chemung age.

This blue shale, covering a black shale, as will be remembered, is itself overlain by another bed of black shale, the Cleveland shale of Newberry, and described by him as ranging from twenty to sixty feet in thickness, and as containing numerous fossils, among which he specially recognizes the scales of Paleoniscus and the teeth of Cladodus and other carboniferous sharks. This last division, viz., the Cleveland shale, he makes the base of the Waverly system. The Cleveland shale is overlain by the Bedford shale which ranges between ten and sixty feet in thickness and which is sometimes red but oftener blue in color. Fossils are quite rare in it as a rule, but they are sometimes found and they agree with those of the Cleveland shale in belonging to Sub-carboniferous forms.

The Bedford shale is followed by the Berea grit, a well known stratum in northern Ohio, of great economic value and so largely worked as to be easily followed. It ranges in thickness from ten to ninety feet and is everywhere poor in fossils.

The Berea grit is in turn covered by the Cuyahoga shale of Newberry, a mass of blue shale interstratified with sandstone beds, ranging from 150 to 250 feet in thickness according to Newberry and extending from the Berea grit to the Carboniferous conglomerate. The Cuyahoga shale abounds in fossils which have long been known and studied and in regard to which no question exists. The lower portion of this stratum was described by Newberry as dark blue or sometimes black in color and heavily charged with fossils, among which a characteristic species of Lingula and also of Discina are reported.

This constitutes the Waverly group of northern Ohio according to the classification of Dr. Newberry in 1870.

The Waverly group of southern Ohio, from the black shale upwards, is found to consist of the following elements. A mass of blue shale, often marked with red bands, from ten to ninety feet in thickness, directly overlies the black shale. It was recognized and described in the State Geological Reports as the Waverly shale, the Waverly blue shale and the Lower Waverly shale. Immediately above it is found the stratum of quarry stone, from which the whole formation derived its name, the thickness of which is between five and fifty feet.

The quarry stone is in turn covered by a very persistent and well characterized bed in central and southern Ohio, which was first recognized and described by the late Professor E. B. Andrews, under the name of the Waverly black shale. It is from fifteen to thirty feet in thickness, is highly charged with bituminous matters and is extremely rich in fish remains, for considerable portions of its extent.

Above the Waverly black shale comes a great mass of blue and sandy shales, interstratified with beds of sandstone, the whole being from 250 to 350 feet in thickness. Some valuable quarry courses occur in this series, especially in its lower portions. In particular, the great quarries of the Ohio valley at Buena Vista and Rockville, from which Cincinnati and the cities of the whole valley have drawn so largely, are found to directly overlie this black shale that I have last named.

A heavy stratum of sandstone which in central Ohio becomes a coarse conglomerate completes the series here. This conglomerate was long a puzzling element. It simulated the true Carboniferous conglomerate perfectly and was mistaken for this stratum by the earlier geologists, but it was assigned to its proper place in the scale by Professor Andrews who showed it to be Sub-carboniferous in age. It is sometimes overlain by the fossiliferous shale and sandstone, to which the same author gave the name of the Logan sandstone, and sometimes by the Maxville limestone which has been proved to be of Chester age.

These are the series of the northern and southern portions of the state respectively, and they seem at first sight to be quite discordant, but their upper and lower limits are the same and a general equivalence must exist. Are there any continuous elements? Can any clew be found to lead out of the confusion?

A false clew was at first adopted and a misleading analogy was followed, to the great disadvantage of our geology.

It will be observed that a comparatively thin bed of black shale occurs in northern Ohio, overlain and underlain by blue shales, viz., the Cleveland shale, overlain by the Bedford and underlain by the Erie shale. A bed of black shale with similar boundaries has been noted in southern Ohio, viz., the Waverly black shale of Andrews. This latter stratum was assumed to be the true equivalent and extension of the Cleveland shale, and its fossils soon came to be credited to the latter. This identification placed the Berea grit of the north and the Buena Vista quarries of the Ohio valley on the same horizon. It also made the Cuyahoga shale the equivalent of the upper Waverly shales, the Waverly conglomerate and the Logan sandstone of southern Ohio. One unfortunate consequence of this identification was obvious. If the Waverly group begins with the Cleveland shale and if the Cleveland shale is the equivalent of the Waverly black shale, we find that the Waverly quarry stonefrom which the whole formation took its name-drops out entirely from the Waverly series, and that this important stratum as well as the blue shale that underlies it, must be placed in the Erie shale. The order is a false one, and it brought confusion into all parts of the series. Students of our scale came to believe that the equivalence of the different portions of the system constituted an unsolved if not an insoluble problem.

Out of this confusion and uncertainty, the Berea grit has helped

to lead us. When firmly held in its stratigraphical extension and truly followed, it proves to be a safe and reliable guide. It bridges the chasm that had been left in our series and stretches in unbroken continuity from the shores of Lake Erie to the valley of the Ohio. It makes a foundation on which the Sub-carboniferous system of the state can be securely built, and it offers the means of correlation for the rocks of our scale, on the one side with those of Pennsylvania and on the other with those of Kentucky, which have already been fruitful in good results.

More than this, if the history which its lithology and structure contain is rightly interpreted, we find in it a very suggestive guide to much of the subsequent geological history of the state.

The Berea grit of northern Ohio is, as its name implies, a sandstone stratum, the first one to be reached in ascending the geological scale of the state. In its best phases, it constitutes a building stone of the highest excellence. Of the quarries that are worked in it at Berea, Amherst, Independence and other points, the annual output already exceeds $1,100,000, according to the carefully gathered statistics of the census of 1880.

The stratum varies considerably in grain, but it is never coarse and only in rare instances does it contain any pebbles. Its boundaries have a picturesque distinctness, the stratum on which it rests being red, and that which covers it being black or dark gray, the latter being also charged with characteristic fossils. There ought to be no difficulty in following such a stratum across Ohio and there is none.

Professor N. H. Winchell first traced it to central Ohio, but to this part of the state, the Waverly quarry stone had been followed from the southward. To abandon the preconceived error, and to accept the now obvious conclusion that these two strata were one, cost time and trouble, but when at last the truth was recognized, it reconciled the facts that had before seemed so discordant and brought the first real harmony into the lower Waverly group of Ohio. The Waverly black shale of southern Ohio proves to be the black base of the Cuyahoga shale of northern Ohio instead of the Cleveland shale to which it was at first referred. The Waverly blue shale of southern Ohio is the Bedford shale of the north, like it also carrying enough peroxide of iron to redden it in many in

stances.

But what of the Cleveland and Erie shales below? The latter is a formation of extraordinary interest and economic value else