Thin seams of phosphorite nodules occur at 

 intervals throughout the succeeding 120 feet of Gault 

 clay, hut they are of inconsiderahle thickness • The 

 most important is that at the junction of the Lower and 

 Upper Gault, Another "bed, some 19 feet ahove the base 

 of the formation not infrequently yields phosphatized 

 carapaces of crahs. These nodules from the main mass 

 of the Gault are generally "buff or grey in colour and 

 are distinguishahle from those in the Lower Greensand 

 and the basal sandy beds of the Gault by their 

 freedom from included sand grains and glauconite. 



Phosphorite is of economic value since it can be 

 converted into soluble superphosphate for use in 

 agriculture as a fertilizer. Prom about I856 to I880 

 there was a great demand for English phosphates and 

 phosphorite nodules were dug in many places. A 

 phosphate works was once established at Cheriton, 

 Here the Mammillatum Bed and the overlying Sul'^hur Band 

 were exploited. The nodules were extracted by means 

 of wide trenches the two phosphate seams being dug 

 out and washed. Scattered nodules were picked out by 

 hand. The washing was effected in circular frames 

 through which a constant stream of water was running, 

 the nodules being kept in motion by travelling rakes. 

 When Y/ashed the nodules were sifted and then carefully 

 picked^ over by boys for removal of pyrites before 

 being carted off to the manufacturer. For conversion 

 to superphosphate the nodules were ground to powder 

 and then treated with sulphuric acid at high 

 temperature. 



The demand for phosphate stimulated exploration 

 in other countries and the introduction of foreigh 

 phosphates brought an end to the industry in England, 

 The Cheriton works was closed in I876, The old 

 v/orkings were still visible up to 1939, but were filled 

 in during the construction of Harcourt School, 



