Building Stones. 6 1 1 



under water. Hence the Lias limestone has always 

 been largely employed in the building of piers and 

 other structures that require to be constructed under 

 water. Cement stones are also found to some extent in 

 the Eocene strata, and are obtained from nodules 

 dredged from the sea-bottom at Harwich, and the south 

 of England. These are transported hither and thither, 

 to be used as occasion may require. 



The chief building stones of our country, of a 

 hewable kind, are the limestones of the Oolitic rocks, 

 the Magnesian Limestone, the Carboniferous Lime- 

 stone, the Carboniferous sandstones, and the sandstones 

 of the Old and New Eed series. The Caradoc Sand- 

 stone, also in Shropshire near Church Stretton, yields 

 a good building stone. The chief Oolitic building 

 stones are from the Isle of Portland and the Bath Oolite. 

 St. Paul's and many other churches in London were 

 built of Portland stone, and the immense quantities 

 of rejected stones in the old quarries, show how 

 careful Sir Christopher Wren was in the selection of 

 material. The Bath stone also affords a beautiful 

 yellow limestone, which comes out of the quarries in 

 blocks of great size, and is easily sawn and hewn into 

 shape. Nearly the whole of Bath has been built of 

 this stone, and it has been largely used in Westminster 

 Abbey and other buildings in London. Excellent 

 building stones are also got from the Inferior Oolite 

 limestone, especially in the neighbourhood of Chelten- 

 ham, from the Cotswold Hills. 



In England the Magnesian Limestone is extensively 

 quarried for building purposes. It is of very various 

 qualities, sometimes exceedingly durable, resisting the 

 effects of time and weather, and in other cases decom- 

 posing with considerable rapidity. The Houses of 



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