It is very durable, as some part of the basement of West minster Abbey appears to have been built with the stone from these quarries. In this case, it seems to have been dressed smooth : and the surface still remains with little alteration ; having withstood the attacks of time with great firmness ; it being, even now, difficult to detect a loosened splinter in the work.
The common rag-stone comprehends all the different kinds which arc met with in these quarries, except that of the above, and that which is of the hassocky nature ; though the true unmixed rag is a distinct sort, having characters different from any of the others. in colour, it inclines more to the red, or liver colour, than that of the cork-stone, but otherwise resembles it considerably. Viewed with a glass, its grain is finer, and the fracture flint-like.
It has of late years come into very extensive use. Its constituents are—carbonate of lime, with a little magnesia, 9:2.6; earthy matter, 6.5 ; oxide of iron, 0.5 ; and carbona ceous matter, 0.4 = 100.
The hassocky-stone appears, to the naked eye, to be of a soft, white, sandy quality ; and its fracture is the seine ; but under the glass, its grain is fine, its contexture uniform, and so thickly interspersed with small seed like granules, of a dark or black colour, as to give it a gray appearance; some times bearing evident impressions of shells. Its texture is loose and brittle, crumbling easily between the lingers into a coarse, sand-like powder. It will not burn into good lime, although it is almost wholly calcareous.
Its principal use is-that of forming a loose friable sort of rubbly sub-soil, in some places, where it is admirably suited to the growth of saintfoin, and some other crops of the plant as well as of the fruit-tree kinds.
The quarries in several other counties contain stony mate rials of all• these different kinds, which are wrought and applied to a variety of uses.
Quarries of marble are wrought in several districts in different parts of the country, and afford great advantages in various ways. In Sussex they have a marble, which, when cut into slabs, is used for ornamenting chimney-pieces, and other purposes. It is equal in quality and beauty to most sorts, when highly polished. For square building and pay Mg, it is also a material scarcely to be excelled. By burning, it likewise affords a very valuable manure, equal, and by some thought superior, to chalk, being cheaper to those who are near the places from which it is dug. It is found the most perfect about Kirdford, at the depth of from ten to twenty feet under ground, in flakes nine or ten inches in thickness, and is called Petworth marble.. It was much
employed in building the cathedral at Canterbury ; the pil lars, monuments, vaults, pavement, &c., being formed of it ; and the archbishop's chair is one entire piece of it. Marble is got in some of the counties in the middle of the island, as Derbyshire, Nottinghamshire, &c.
At Beacon-hill, near Newark, a blue stone for hearths is obtained, which approaches to marble, and is capable of burning into lime. And, in the county of Derby, much good marble is raised in different places.—In Lancashire there are quarries of fine black marble, besides stones which approach to, and take on the polish of marbles. In many of the western and northern parts of Yorkshire, marble of vari ous kinds is found, some touch resembling, and others supe rior, in closeness of texture and distinctness of colours, to that which is wrought in Derbyshire. Also a stone, which greatly resembles the marble of that county, and which is capable of receiving much such a polish, and is nearly of the same colour, mixture, and appearance.
hi the county of Inverness, likewise, marble of the greatest variety of colours, and of the most beautiful shades, has been met with in Ben-Nevis; and inexhaustible quarries of it lie untouched in the islands which belong to it.
Besides, this sort of material exists in immense quantities in quarries in many other parts of the kingdom.
Chalk is a material which is raised from quarries and pits, mostly in the southern parts of the country. as in Sussex, Surrey, Kent, Essex, Berkshire, Hertfordshire, &c. It exists in vast ranges and tracts in most of these districts, whence it is dug up from quarries, at different depths, according to circumstances, exposed in sheds to dry when wet, and then converted into lime for various uses, by means of fire : or it is employed in its broken and powdery state, without under going the above processes, by merely digging it out of such places. in some parts, as in Kent, and the neighbouring districts, it is often dug and raised from considerable depths, from beds of very great thicknesses. And near Reading, in Berkshire, there is a stratum of this substance, which is thirty feet in thickness. It is there used and dug out for manure, and occasionally as a building material ; for the latter of which purposes it is very durable. The remains of the abbey of Hurley, and of the ancient chapel, now the parish church, built wholly of chalk, in the reign of William the Conqueror, are still as fresh and sound as if they had been the works of the last century. Chalk, when once indurated by the air, has a remarkable property of resisting the action of the weather.