Page:Notes on the State of Virginia (1802).djvu/49

Rh Rockfiſh. The ſamples I have ſeen, were ſome of them of a white as pure as one might expect to find on the ſurface of the earth: but moſt of them were variegated with red, blue, and purple. None of it has been ever worked. It forms a very large precipice, which hangs over a navigable part of the river. It is ſaid there is marble at Kentucky.

But one vein of lime-ſtone is known below the Blue ridge. Its firſt appearance, in our country, is in Prince William, two miles below the pig-nut ridge of mountains; thence it paſſes on nearly parallel with that, and croſſes the Rivanna about five miles below it, where it is called the South-Weſt ridge. It then croſſes Hard-ware, above the mouth of Hudſon's creek, James River at the mouth of Rockfiſh, at the marble quarry before ſpoken of, probably runs up the river to where it appears again at Roſs's iron-works, and ſo paſſes off ſouthweſtwardly by Flat creek of Otter river. It is never more than one hundred yards wide. From the Blue ridge weſtwardly, the whole country ſeems to be founded on a rock of lime-ſtone, beſides infinite quantities on the ſurface, both looſe and fixed. This is cut into beds, which range, as the mountains and ſea-coaſt do, from ſouthweſt to north-eaſt, the lamina of each bed declining from the horizon towards a paralleliſm with the axis of the earth. Being ſtruck with this obſervation, I made, with a quadrant, a great number of trials on the angles of their declination, and found them to vary from 22° to 60°; but averaging all my trials, the reſult was within one third of a degree of the elevation of the pole or latitude of the place, and much the greateſt part of them taken