Geology. 229 



and modern workings, extending for miles underground. 

 Consisting of beds of shelly limestones and fine freestones, 

 it may be divided into 



/ I. Coarse shelly limestone. 1 



Upper Rags. \ 2. More or less fine Oolites. (. j°f° 



( 3. Tough brown argillaceous Limestone. ) 

 Fine Freestone ... ... ... 10 to 30 



Lower Rags. Coarse shelly limestones ... 10 to 40 



Near Gloucester and in Oxfordshire the Great Oolite 

 thins out to 60 ft. 



In the quarries, the most celebrated of which are situated 

 at Box, Farley, Hampton, and Combe Down, the workmen 

 generally leave one of the "Rag"* beds — a hard, tough, 

 shelly limestone — to form the "roof," as less liable to give 

 way, and work out the softer and finer-grained beds beneath, 

 leaving another " rag " bed as the floor. The stone, when 

 first cut in its green state, is quite soft, and of a warm, 

 yellow colour, but hardens and whitens much by exposure 

 to the air and the evaporation of the moisture. It has been 

 stated that a cubic foot of Bath stone will absorb one gallon 

 of water. The spherulitic granules or eggs (whence its name), 

 of which the rock is composed, have often been examined 

 microscopically, and usually fail to present any organic struc- 

 ture, consisting merely of concentric films of carbonate of lime. 

 The beds so much used in building are not by any means 

 highly fossiliferous, though here and there rmnntQ ■ mollusca 

 and a stray palatal tooth occUrs. But on the Cotteswold 

 hills, particularly at Minchinhampton, they are especially rich 

 in fossils. The absence of organisms indeed renders them 

 the more easy to work ; but the beds which form the " roof" 



* Rag is a term used by the workmen for those beds containing shells, 

 and less easy to work. 



