84 LONDON DISTRICT. 



Reference to the Chislehurst c pit ' occurs as early as the 

 13th century, as noted by Mr. W. Johnson, who mentions also 

 that chalk was brought up in baskets from a shaft in the early 

 part of the 19th century. 1 The mining of chalk for lime-burning 

 was continued until about 1854. When it began is uncertain, 

 but the opinion was long ago expressed, and is supported 

 by Mr. W. J. Nichols, that the outer galleries may have been 

 worked for the manufacture of lime by the Romans. 2 



Mr. T. V. Holmes has noted subterranean chalk-chambers on 

 the northern side of Beacon Hill, Purfleet, and certain shafts met 

 with at Aveley and near West Thurrock, that were probably 

 made for domestic use as dene-holes. 3 



In the manufacture of lime, both for agricultural and building 

 purposes, the Chalk has been largely utilized. The upper beds, 

 which contain from 95 to 97 per cent, of calcit? carbonate, yield 

 the best ' white lime ' for use on the land. Lime for mortar 

 used in building St. Paul's Cathedral was obtained from the 

 Chalk at Sutton. 



Whiting is prepared from the Chalk in the neighbourhood of 

 West Thurrock and Greenhithe; and in these areas lime and 

 Portland cement are extensively manufactured from chalk, 

 with an admixture of clay and other ingredients. Cement is 

 also manufactured from the Chalk at Harefield and Waddon. 



Septaria, or cement-stones from the London Clay, were 

 formerly used in the manufacture of Roman cement, and quite 

 recently they, and also London Clay, have been utilized for 

 cement-making by the Associated Portland Cement Manufac- 

 turers in the neighbourhood of Swanscombe, not far from 

 Greenhithe. 



Gun-flints were manufactured from chalk-flints in olden times 

 at Chislehurst, Crayford, Greenhithe and Purfleet. Flints have 

 also been sent to Staffordshire for use in the manufacture of 

 pottery. 



Large quantities of chalk were carried away as ballast for 

 vessels during the 18th century; much is now exported to 

 America. 



BRICKEARTH AND CLAY. 



In and around London extensive brickyards have been 

 opened, more especially in the Thames Valley brickearth and in 

 the London Clay. 



Brickearth has been worked at intervals since the time of the 

 Roman occupation, and potter's earth from the Bronze period. 

 The Romans made bricks in the south of England, but subse- 

 quently to their occupation of this country the manufacture 

 appears to have been abandoned until the latter half of the 

 15th century, although tiles were made. 



1 Folk-Memory,' 1908, pp 231-233. 



2 Athenceum, Feb. 27, 1904, p. 276; see also Journ. Brit. Arch. Assoc., N.S., 

 vol. x, 1904, p. 64. 



3 Essex Nat., vol. xv, 1907, p. 6. 



