[74 ECONOMIC GEOLOGY 
tension; and as the material is not plastic it remains friable 
so that all the surface is reached by the liquid that is being 
filtered. England formerly produced the largest quantity, 
which mainly came from a bed known as “the Fuller's 
Earth ” in the Lower Oolite of Wiltshire. Its existence led 
to the establishment there of the early woollen industry. 
The second important English deposit is in the Lower Green. 
sand of Nutfield and Reigate in Surrey. In America Florida 
earth is largely used for the discoloration of oils. .The 
American fuller’s earths are very varied in character and 
origin ; that in Arkansas occurs in veins formed by the altera- 
tion of basalt dykes; the Bentonite of Tennessee is an 
altered volcanic ash; that of Massachusetts is a glacial silt. 
The production of fuller's earth in* England in recent 
years has varied from about 20,000 to 30,000 tons, and its 
price has been about £2 per ton.