586 MESSES. GAET):JfEIl, EZEEPING, AND MOFCEiTOlS^ ON THE 



naceous matter and a band of ironstone Septaria thi^oughont a part 

 of their horizontal extent. The base is not visible here, but can be 

 seen at Hengistbury Head *. Eight feet above the beach there is 

 a scattered line of typical Bracklesham pebbles, and another more 

 considerable layer of the same capping the white sandf. The 

 flints are moderate in size, either quite white or black, and mixed 

 with small quartz-pebbles and grains, and lignitic matter abraded 

 and worn into pellets. The upper layer is imbedded in warm-drab 

 loamy sand, with pale green grains and sulphur-yellow partings and 

 pipes, giving a green streak to the tool. Casts of bivalves abound 

 in the upper pebble-bed, and, like the pebbles themselves, are most 

 numerous at the base. The pebbles extend upwards throughout 

 nearly 3 of the 4 feet of loamy sand composing the bed. Mr. 

 Osmond Eisher looked on the upper pebble-bed as indicating a 

 natural physical break, though he addedj, '^ the division is probably 

 in reality one of convenience only, the two groups forming a con- 

 tinuous series, changing gradually throughout in its lithological 

 character and fauna." Prestwich considered that there was no 

 break between the two formations. A dozeu fossils were determined 

 by Pisher from the sand, and 18 from the pebble-bed, only 4 of 

 which are Gasteropods. The last 10 feet is very green, stiff, sandy 

 clay, rifle-green when fractured, but of a bright green colour when 

 scraped. It abounds with wood, mostly Teredo-hoTed, and well- 

 preserved fir-cones are not uncommon in it. Its angle of repose is very 

 steep, and the abundance of green grains enables it to be distinguished 

 easily from the overlying series. Casts of MoUusca abound in this 

 part of the series, and are seen to belong to species that pass into 

 the Bracklesham below as well as the Barton above §. 



At this horizon there is a band 9 inches thick of ferruginous 

 loam or imperfectly formed ironstone, mottled with green and con- 

 taining grains and small pebbles of quartz. It was described by 

 Prestwich as a band of tabular soft Septaria mixed with green-sand |!f 



* " Description and correlation of the Bournemoutli Beds. — Part I. Marine 

 Series, by J. S. Grardner," Quart. Journ. Geol. Soc. vol. xxxr. (1879) p. 214. 



t This is coarse quartz-sand of largish subangular to rounded grains, mixed 

 with very minute grains. 



I Quart. Journ. Geol. Soc. vol. xviii. (1861) p. 88. 



§ Osmond Fisher, I. c, gives the following list: — Fusus ■pyrus, Pyrula 

 nexilis, Voluta nodosa, Bentalium, Cardimn seojiistriatum, Cardita (small ribbed), 

 Cytherea (a Barton species). Crassatella costata, Corbula pisum. An analysis of 

 the beds is also given, p. 86 :— 



Water 10-02 



Silica oO-ll 



Iron protoxide 25'04 



Alumina 6*12 



Magnesia 3'14 



Potash 5-17 



99-60 



II Quart. Journ. Geol. Soc. vol. v. (1849) p. 45. 



