This suite of rocks offers many objects worthy of a minute inquiry, far beyond the limits of these short notices.
A very excellent account is given of the Veryan limestone by S. J. Trist, esq. in the first volume of the Transactions of the Geological Society of Cornwall.
Mr. Trist says,
The limestone occurs on the coast at Pendower Beach, and may thence be traced for a mile and a half inland.
It comes to the surface, in three different places, nearly equidistant from each other, but at different elevations, the most inland being probably a hundred and twenty, or thirty feet above the level of the sea. In each instance it creeps out at the brow of a hill, and no where appears in the vale below, where it would seem originally to have stretched across the valleys, but to have been subsequently carried away, together with the accompanying matter, by diluvian action.
In breadth it extends over a superficies of 350 yards, but alternates with an argillaceous schist, the lime itself never exceeding three feet in thickness, and that only in the upper beds of the strata. The lime scarcely amounts altogether to one eighth of the whole mass.
According to an analysis made by the Rev. William Gregor, a good specimen of this stone consists of about nine parts in ten of carbonate of lime.
Mr. Trist then gives a comparative statement of the results from calcining this limestone, and the well-known limestone of Plymouth, that 200 Winchester bushels of lime from the kiln, provincially called shells or foreright lime, are produced from 11 tons of the Veryan limestone, by the consumption of 46 Winchester bushels of culm, more universally known as Welsh stone coal; but that 14½ tons are required of the Plymouth limestone to give the same quantity of lime from the kiln, with the consumption of 56 bushels of culm, which would make the Plymouth limestone inferior to that of Veryan, in about 32 per cent.
as to quality, and about 22 per cent. more in regard to fuel. As a cement, its quality is remarkably good. Small spherical masses of oxide of iron occur in great abundance; they are, in the opinion of Mr. Gregor, pyrites in a state of decomposition, the sulphur having escaped.