452 OLIGOCENE. 



Hastingsicc, Trionyx (several species) and Emys crassns} The 

 thickness of the Lower Headon Beds between Long Mead End 

 and Paddy's Gap is about 80 feet, according to measurements by 

 Messrs. E. B. Tawney and H. Keeping. The beds consist of 

 greenish marly clay and sands. 



The Lower Headon marls have been used for marling lands in Hampshire. 

 The Lower Headon Beds of the Isle of White furnish white glass-house sand 

 of fine quality. 



Middle Headon Beds. 



Colwell Bay Marine Bed, etc. — The Middle Headon Beds con- 

 sist of sand and sandstone with clays attaining a thickness of about 

 100 feet. At Headon Hill they contain a brackish-water fauna, 

 yielding Potamities ductus, P. ventricosus, P. concaviis, Neritina 

 concava, Cerithium concavum (taken sometimes to indicate a zone), 

 Cytherea iticrassata, etc. Further north in Colwell Bay the upper 

 and lower portions of the series are marked by the presence of 

 brackish-water MoUusca, but the central part assumes a distinctly 

 marine character (Colwell Bay Marine Bed), consisting of clays 

 with Cytherea mcrassata (Venus bed), and containing also Oyster- 

 beds with Ostrea flabellula. Planorhis eiiomphalus, LinuicEa longiscaia, 

 and Paliidina lenta abound in the freshwater beds, and Chara 

 Wrightii is abundant in the Neritina bed (with N. concava) at the 

 base of the series. Trigonoccclia deltoidea occurs in a layer above 

 the Neritina bed. 



Brockenhurst Beds. — In 1858 Mr. H. Keeping collected a series 

 of fossils from Cutwalk Hill, near Lyndhurst, but attention was not 

 particularly directed to the fauna until 1864, when Baron Adolf von 

 Koenen observed that the railway-cuttings at Whitley Ridge in the 

 New Forest (Brockenhurst, etc.) had exposed certain marine beds 

 overlying the Lower Headon (freshwater) series, and containing 

 fossils which he believed to constitute the marine equivalent of the 

 Middle Headon strata.* The Brockenhurst Beds occur at the base 

 of the marine Headon Beds at Brockenhurst and Lyndhurst, and 

 also at Whiteclifif Bay (14 feet), but they have not been recognized 

 at Colwell Bay and Headon Hill. 



The Brockenhurst Beds yield Valuta spinosa, Pisania fFususJ 

 labiata. Typhis pungens, Pleurotoma transversaria, P. Hantoniensis, 

 Ostrea ventilahrum, Cyti^erea Solandri, Psammobia ccstiiarina, Corbula 

 pisum, etc. The fossils obtained at Whitley Ridge railway-cutting 

 differ a little from those obtained from a brickyard at Roydon in 

 the same neighbourhood, and this has led Messrs. Keeping and 

 Tawney to divide the beds into two zones, both of which are on a 



1 S. V. Wood, London Geol. Journal, No. i, p. i ; Dr. T. W^right, Proc. 

 Cotteswold Club, i. 120 ; Marchioness of Hastings, Bull. Soc. Geol. France (2), 

 ix. 141 (the collection made by this lady is in the British Museum) ; Tawney and 

 Keeping, Q. J. xxxix. 566; W. Davies, G. Mag. 1884, p. 433 ; R. Lydekker, Ibid. 



443' 547- 



"- Q.J. XX. 97; G. Mag. 1867, p. 507. 



