Beds of underclay so invariably accompany seams of coal that some have come to the conclusion that there was no exception to the rule. Here however is one, in the case of the Little Flint coal, which lies immediately upon a sand rock. Evidently it was not formed like peat from vegetation which grew and accumulated on the spot. There is no underclay to support the roots of ordinary coal-measure plants, but the coal follows closely the contour of the rock on which it lies; as though it had flowed over it and had been laid down upon it like a sheet of bituminous matter. And there is not the least doubt but that this was the case. Sigillarias, Lepidodendrons, Calamites, and tree-ferns flourished on the slime now hardened into shale, and which shows sun-cracks, and worm-burrowings, indicative of the then surface, with tracks of locomotive mullusca, as they dragged their shells along the soft impressionable slime. Heavy tropical rains then falling upon some upraised and exposed Caradoc or perhaps Millstone grit lands, the latter scarcely yet consolidated, brought down and held in suspension a quantity of sand which, as it settled down, formed a bed varying from three to thirty feet in thickness. The body of water which contained so much sand must, of course, have been much greater, and would probably cover the whole of the vegetation. The result was that the lower parts of the largest trees which were buried first were preserved in situ. The upper parts toppled over and lay embedded in the sand, as we find them. In both cases the vegetable matter decayed and was replaced atom by atom with fine sand; but the vegetable tissues, oil, and seeds, being lightest, rose above the sand, forming a pulpy bituminous plastic bed, which first fermented, and then crystalized into coal. Even the little disc-like seeds of the sigillaria, which make up a considerable portion of the coal, and which floated with other matter, lie flat and parallel with the lamina of the coal itself. Nor is this the only instance of the kind. The Top coal of Halesfield and Kemberton shews signs of liquefaction; portions of fish, such as teeth, bones, and scales being embedded in the coal. We ought to add in connection with the Black Rock section that the five feet of clunch over the Little Flint Coal is the underclay for the Clod Coal, and is full of roots and rootlets. [Picture: Trees, fens, swamp] The descent from the Crawstone crust to the Silurian shale of the Dale cannot be traced. As passed through at the Limestone pit at Lincoln Hill, it was as follows:—