THE OOLITE.
The division of the secondary formations, called “Oolite,” takes its name from the most characteristic of its constituents, which is a variety of limestone composed of numerous small grains, resembling the “roe” or eggs of a fish, whence the term, (from the Greek oon, an egg, lithos, a stone). The oolite, however, includes a great series of beds of marine origin, which, with an average breadth of thirty miles, extend across England, from Yorkshire in the north-east to Dorsetshire in the south-west.
The oolite series lies below the Wealden, and where this is wanting, below the chalk, and consists of the following subdivisions, succeeding each other in the descending order:—
| Oolite. | |
|---|---|
| Upper. | Portland stone and sand. |
| Kimmeridge clay. | |
| Middle. | Coral rag. |
| Oxford clay. | |
| Lower. | Cornbrash and forest marble. |
| Great oolite and Stonesfield slate. | |
| Fuller’s earth. | |
| Inferior oolite. | |
Upon the portion of the island representing the oolite series, the most conspicuous of the restored animals of that period is—