526- EEPOET — 1882. 



having strengtliened the previous labours of Forbes and Bristow, and the later re- 

 searclies of Messrs. Tawney and Keeping have still more firmly established the 

 succession and correlation of the Middle Headon series of the island, and aflbrding 

 a basis for further research and analysis for the ' Anglo-Parisian or Hampshire 

 Tertiary Basin.' 



Mr. Tawney prepared an important paper upon the Upper Bagshot Sands of 

 Hordwell Cliff, which was read before the Cambridge Philosophical Society and 

 published in their Proceedings. The object of the communication was to discuss 

 the affinities of the Bagshot series with a view to their classification, and also to 

 endeavour to show their correlation and equivalents in the Paris basin. 'All 

 observers are agreed as to the actual position of the sands lieing below the fresh- 

 water Lower Headon. Edward Forbes and the Geological Survey distinctly ally 

 it to the Marine Bagshot beds. They place it in the Middle Eocene Bagshot series, 

 terming it Upper Bagshot (instead of Headon Hill Sands). Forbes noticed the 

 fact of its containing Barton species at Whiteclift' Bay. This shows its afiiuity to 

 Barton beds. Dumont favoured a similar classification in his essaj', and in his 

 table the Headon Hill sands are grouped with the Barton clay as being respectively 

 equivalent to the upper and lower divisions of the Behjian Laekenian, while the 

 Headon Hill limestones and marls are placed in the Tonr/rien. Lately these views 

 have been questioned by the author of the ' Oligocene Strata of the Hampshire 

 Basin,' in the 'Quarterly Journal of the Geological Society,' vol. xxxvi., who 

 regards these beds as constituting the lowest member of the Headon group, stress 

 being laid upon the occurrence of Cerithiuni concaiiim as a test. The author also 

 places the whole of the Upper Bagshot sands and the Lower and Middle Headon 

 beds as the equivalents of tlie jNIortefontaiue sands, placing them above the St. 

 Ouen limestone ; these St. Ouen beds representing perhaps the Osborne, and all 

 three Headon divisions, which come above the Mortefontaine beds. Ceritldum con- 

 cavum is said to occur both in the Bagshot and Headon series. Careful research 

 and examination shows that the shell in question is Lamarck's C. pleurotomoides 

 in the one case, and not C. concavum, which species has evidently been con- 

 founded with the Lamarckean shell. Examination of equivalent beds in France 

 by Mr. Tawney, and the researches of Professor Hebert and M. Munier-Ohalnias 

 clearly show that the Mortefontaine sands do not contain Cerithium concavuyn, 

 the sliell so common on that horizon being C. plei(roto7noides Lamk. Gompariaon 

 of the Headon shell with those brought from near Mortefontaine shows that 

 the Long Mead End species agrees with the French form. It would appear that 

 there is much greater parallelism between the French and English series than we 

 have hitherto expected. The Mortefontaine sands are the upper part of the Sables 

 de Beauchamp, representing our Barton beds; above this comes the Oalcaire de 

 St. Ouen, chiefly of fi-eshwater origin. Connected with the St. Ouen limestone are 

 sands and marls, containing at the top and bottom Cerithium concavum abundantly. 



The St. Ouen period, therefore, witliout doubt represents our Headon series. 

 'In our Hampshire basin the freshwater and marine condition in the Headon 

 series are not in the same order as in the St. Ouen beds.' ' The marine facies in 

 Hampshire, with C. concavum, comes between the freshwater Lower and Upper 

 Headon deposits, near Montjavoult ; tlie bulk of the freshwater limestones is in 

 the centre or between two deposits with this CeritJnum conr(ivu?)i.' ' In the Paris 

 basin, therefore, the zone of C. concavum is not connected with the zone of 

 C. pleurotomoides, but comes immediately above it.' Thus C. concavum charac- 

 terises the Middle Headon of Colwell Bay and Hordwell, while C. pleurotomoides 

 is found only in the Upper Bagshot of Long ilead End. That the Long Mead 

 End sands and those of Mortefontaine are equivalents few can doubt. Both 

 succeed or constitute the uppermost portion of the Barton beds, and 2-5 per cent, 

 of the fossils are in common. These affinities show that the term Upper Bagshot 

 sands is the most appropriate, and expresses the relationship of these sands, since 

 the Barton and Bracklesham beds together are usually considered as the equivalents 

 of the Middle Bagshots. The author believes, therefore, that it would be wi'ong to 

 reject Edward Forbes's name of 'Upper Bagshot' for the Long Mead End sands, 

 and accept in place of it the older term of Headon Hill sands. 



