Shale Mass Research Articles

III.—The Upper Devonian Fishes of Ohio

Under the true Carboniferous strata of Ohio, that is below the base of the Berea Grit, lies a mass of shale of varying colour many hundred feet in thickness. The uppermost fifty or sixty feet are often red or reddish, and have been separated with the name of the Bedford Shale. The next layer, of about the same thickness, is usually black or at least very dark and bears the name of the Cleveland Shale. Below this again is a greenish mass 500 feet or more in thickness, known as the Erie Shale. Another dark bed follows—the Huron Shale—beneath which is the great limestone base of the Devonian in Ohio, the Corniferous.

On the Fish-remains found in the Cannel Coal in the Middle Coal-measures of the West Riding of Yorkshire, with the Descriptions of some new Species

In paper I had the honour to read before this Society in 1876*, a section of the strata composing the West Riding of Yorkshire Coal-field from the Elland Flag rock to the Blocking Coal is given. The Blocking Coal is probably the equivalent of the Silkstone Coal of the more southern part of the Coal-field, and is regarded by the members of the Geological Survey as the most convenient stratum to form the dividing line between the Lower and Middle Coal-measures. The coal-seams yielding the fossil fish-remains which form the subject of the present paper occur about 400 feet higher in the series than the Blocking Coal. The following section may serve to give an idea of the position of the Stone- or Gas-coal of Adwalton and the surrounding district :— The whole series exhibits considerable variations in the character and relative thickness of the strata. The coals, though perhaps more persistent than the other members of the series, do not form an exception. Sections exposed in pits and borings in different localities prove the coals to thin off in certain directions and almost disappear; in some the coal is divided into two bands by lenticular masses of shale or sandstone many feet in thickness; in others two beds of coal gradually converge and form one thicker bed. In this respect the Middle Coal-measures differ from the Lower Coal-measures. The latter, especially in the Lower or Halifax series, are remarkably persistent. The Halifax hard and soft coals extend over the

On the Mode of Occurrence of Diamonds in South Africa

The conditions under which diamonds occur in South Africa are quite different from those of every other known locality, and are so unusual as to deserve the earnest attention of all geologists. It is quite certain that the present “dry diggings,” such as “Colesberg Kopje,” “Du Toit's Pan,” “De Beer's,” “Bultfontein,” and “Jagersfontein,” are being worked in the rock which has brought the diamonds to the present surface; they all possess certain common features of very marked character. Each area is more or less circular in form (fig. 1, a ); the boundary of each is usually horizontal, or nearly horizontal, shale. At the junction, and back for a distance of from one to several feet, the edges of the shale are bent sharply upwards (fig. 1, b ). The contents of these “pipes” in the shale are the same in all cases, and show distinctly that they are of igneous origin. The base is more or less decomposed gabbro (?) or euphotide (?), through which are scattered particles, fragments, and huge masses of shale, nodules of dolerite, occasional fragments of chloritic schist, micaceous schist, and gneiss. The principal foreign ingredient is the shale, which in many places, particularly at Colesberg Kopje, is thoroughly comminuted, forming a breccia , with euphotide (?) as a base. Where large masses of shale occur, the lines of bedding, as might be expected, are not horizontal, but lie in all directions.