BRICKEARTH AND CLAY. 85 



In Sir Christopher Wren's account of the foundations of St. 

 Paul's Cathedral he noted from 4 to 6 ft. of close hard pot-earth 

 over sand and gravel. This pot-earth ' had been used at a Roman 

 pottery, near the north-east angle of the present church.' 1 



In many places the level of the land has been considerably 

 decreased by excavations for brickearth. Thus, along the 

 borders of the Kingsland Road large areas were lowered from 

 4 to 10 ft., and afterwards levelled and laid down to grass. 2 



Brickearth from 2 to 9 ft. in thickness was formerly worked 

 east of Bromley-by-Bow, at Bow, Old Ford, Homerton, and 

 Hackney. It was cleared off large tracts, exposing the gravel 

 beneath, which alone is depicted on the Geological Survey map. 

 This process of artificial denudation is carried on at the present 

 day in the neighbourhood of West Dray ton, Hayes and Southall ; 

 at the last locality, as also at Shepherd's Bush and Acton Vale, 

 the brickearth is practically exhausted. Near Hayes ' the 

 bricks are made of a mixture of brickearth, ashes, and chalk. 

 They are first sun-dried, and then stacked in kilns and burnt. 

 The brickearth having been removed, the gravel is then sold at 

 so much an acre, and worked to within a foot of the water level.' 3 



East of London the brickearth has been largely worked at 

 Ilford and Upminster, but some of the famous brickyards at 

 Uphall, south of Ilford, and elsewhere are abandoned or obscured 

 by buildings. 



Forty or fifty years ago brickearth was largely dug at 

 Clapton, Stoke Newington, and over the area of Highbury New 

 Park; here, in most cases, the old pits were filled with 

 rubbish. Northwards brickyards are now worked near Edmonton 

 and Enfield. 



To the south of the Thames the brickearth is worked between 

 Crayford and Erith; and an alluvial clay from the marshes of 

 Stone has also been dug for brickmaking. 



The Clay-with-flints and associated brickearth on the Chalk 

 plateau have been used for brickmaking ; arid at one time the 

 Boulder Clay and associated beds of reconstructed London Clay 

 at Finchley were worked for the same purpose. 



The plastic clay and sands of the Reading Beds are utilized 

 in the manufacture of bricks, tiles and pottery, notably near 

 Plumstead and East Wickham, while at Nonsuch Park, Ewell, 

 bricks have been made from sandy clay, called ' fire-earth ' 

 (see p. 20). Reading Beds are now largely worked for bricks 

 in the Harefield district. 



The London Clay is extensively dug for making tiles, drain- 

 pipes and pottery, and, mixed with sand and sometimes with 

 chalk, largely utilized for brickmaking. The pits are mostly 

 in the upper part, now known as Claygate Beds, as on the west 

 of Harrow, at Willesden Green, Buckhurst Hill, Loughton and 



1 Buckland, Trans. GeoL Soc., vol. iv, 1817, p. 288. 



2 Middleton, ' Agric. of Middlesex, 1 Ed. 2, 1807, p. 23. 



8 de Sails, R. Fane, Proc. GeoL Assoc., vol. xviii, 1904, p. 410. 



