372 CRETACEOUS. 



Four divisions are noted at Folkestone by IMr. F. G. H. Price :^ — 



Sands and conglomeratic bed, about 7 feet. Zone of Arnvionites 



mafumillaris. (Junction-bed with Gault.) 

 Calcareous sandstone (Folkestone Stone) and sand, made up 



largely of Sponges 60 feet. 



Clayey sandstone 2 ,, 



Brown ferruginous sandstone with phosphatic nodules i ,, 



In places there occur beds of greenish clayey sandstone, which 

 owe their colour to the deposition of glauconite in the interior of 

 shells of Foraminifera, etc. The upper (or Junction) bed com- 

 prises coarse grit, composed of quartz, jasper, etc., with phosphatic 

 nodules, and contains Ammonites mammillaris, Exogyra conica, etc. 

 M. Gaudry in 1859 proposed to place this bed with the Gault.' 



The Folkestone Beds contain Ana Raulini, Lima clongata, Ostrea 

 frons, L^icina Arduciiensis, Aviciila pcctinata, Panopaia plicaia. Pec ten 

 ( Janira) quinquecostatiis, P. orbicularis, Exogyra sinuata, Terebratula 

 biplicata, T. sella, Rhynchonella depressa, Waldhcimia pseiido-jiirensis, 

 Serpula filiciformis, and Ichthyosaurus campylodon. 



The beds are not as a rule fossiliferous, but specimens have 

 been found at Copt Point, Folkestone. The Folkestone Beds form 

 a very persistent stratum beneath the Gault in the Wealden district. 



The term Carstone is applied to a ferruginous grit of irregular nature, which is 

 largely quarried for road-metal at Pulborough, Fittleworth, Trotton Common, 

 etc. In Woolmer Forest it is termed the Forest Stone. At Ightham hard green 

 grit is found in large masses on the Common, and called the Ightham Stone. 



Sometimes phosphatic nodules occur in the upper part of the series, at the 

 junction with the Gault : they have been worked at Farnham. They occur also 

 at the base of the Folkestone Beds. 



Glass-sand is often dug from the Folkestone Beds ; large quantities of white 

 sand are obtained for this purpose at Reigate (Reigate Sand), and also in Kent at 

 Aylesford (25 feet), Berstead (Berstead Sand), White Heath near HoUingbourn, 

 and elsewhere. 



Mr. Topley observes that the Folkestone Beds form an exceedingly sterile soil, 

 especially where they spread over a wide tract or make high ground, as on Albury, 

 Black, and Farley Heaths. The escarpment of the Folkestone Beds, overlooking 

 the lower ground of the Sandgate Beds, is well marked in many places.-* 



In the Kentish Town boring, and at Tottenham Court Road, 

 London, there was no trace of Lower Greensand, while at Rich- 

 mond it was proved to have a thickness of about ten feet, at 

 Caterham twenty feet, and at Chatham forty-one feet.* 



1 P. Geol. Assoc, iv. 138. 



2 Bull. Soc. Geol. Fr. (2), xvii. 32; G. Mag. 1SS2, p. 92; C. Barrois, Ann. 

 Sec. Geol. du Nord, iii. 23. 



3 Geol. Weald, p. 25S. 



* Whitaker, Geol. London, ed. 4, p. 20 ; Judd, Q. J. xl. 744 ; Prestwich, Q. J. 

 xxxiv. 909. 



