There are several quarries in the neighbourhood of Bath, among which may be mentioned the following: -
Found in beds from 10 inches to 41/2 feet thick. A coarse but sound stone, which weathers well except in a smoky atmosphere and by the sea. It is harder than Combe Down, but freer from vents. The stone is not now so easily worked as it used to be.
Combe Down stone differs in quality according to locality. The old quarries of this name are worked out. A new quarry, called Lodge Stile Combe, has been opened, which is said to produce a stone particularly suitable for exposure to smoky atmospheres or sea air, of a light colour, and in beds from 1 to 5 feet thick.
Farleigh Down stone is soft and very fine grained. It occurs in different beds, from 10 inches to 31/2 feet thick, some of a yellow, and others of a red colour. The former does not weather well, and is used for tracery and internal work.
Westwood Down is produced from a quarry somewhat recently opened, and is stated to be a very superior stone, free from vents and defects, and procurable in large and sound blocks.
This quarry consists of three principal varieties in several beds. The "soft scallet," in beds about 3 feet thick, is found about 90 feet below the surface. The stone from these beds is of fine grain, and suitable for sculpture and mouldings. Next below is the "corngrit," about 4 feet thick, a harder stone, full of little pieces of flint; of a good colour, sound, and durable, but unable to resist frost. It is difficult to work, but good for carrying weight, and used chiefly for engine beds, columns, landings, steps, etc. Below this again is the "bottom bed," an excellent soft stone, about 41/2 feet thick, but occasionally stained with blue patches.
Corsham Ridge is also a recent quarry, and supplies good hard stone. It was used for the face work and carved pediments of the Royal Aquarium at Westminster.
Stoke Ground is an old quarry which has recently been worked with vigour. It consists of one bed about 61/2 feet thick, yielding blocks up to 6 tons weight. The stone is of a light brown colour, soft, easy to work, fit for carving, and when seasoned for external work.
Portland Stone is obtained from the upper parts of the Oolitic series.
It has already been mentioned that there are four distinct varieties of Portland stone used for building, of which, however, three only are generally sent into the market.
The section of a quarry given at page 7 is here reproduced for convenience, but it will not be necessary again to describe the order in which the different varieties occur.
Beginning at the top of the quarry and working downwards, we find (interspersed with cap, flinty tiers, and other beds useless for building purposes four varieties of stone all more or less useful to the engineer or builder These are True Roach, Whitbed, Bastard Roach or Curf, and Basebed.
As these four varieties of stone differ greatly in their characteristics and in the uses to which they may be applied, it will be well to describe them separately.