1881.] Hordwell Cliffs, Hampshire. 149 



from French authorities. The Geological Survey is followed as 

 far as the Middle Eocene is concerned. 



The parallelism of the beds in both basins is conspicuous when 

 arranged in this way. It will be noticed in passing that in the 

 Hampshire basin the beds placed opposite the Calcaire de St Ouen 

 are very much thicker than that deposit, while on the other hand 

 the thickness of the French gypsum series is enormous compared 

 to our Bembridge limestone. It is possible therefore that our 

 Osborne freshwater beds which succeed the G. concavum zone are 

 contemporaneous with the lower part of the gypsum series 1 . 



The analogy between the Long Mead End sands and those of 

 Mortefontaine concerns us more. That they are equivalents few 

 can doubt on considering that both immediately succeed the Barton 

 beds, or rather constitute its uppermost portion ; the fossils which 

 they have in common- — about 25 per cent. — also tends to confirm 

 that conclusion ; while if the Cerithium which each contains is 

 acknowledged as identical, the proof is still more positive. 



From this would follow, that the Upper Bagshot sands is the 

 most fitting name to express the relationship of these sands, since 

 the Barton and Bracklesham beds together are usually considered 

 as the equivalents of the M. Bagshot. Of course few would be 

 disposed to maintain that the division — Upper Bagshot sand — is 

 exactly equivalent in the Hampshire and Bagshot areas. Fossils 

 being scarce in the latter no detail horizons can be drawn there. 

 It would be hard to say what part of the Middle Bagshot cor- 

 respond to the top of the Barton beds in Barton cliffs. Indeed 

 some considerations have lately been put forward 2 which make it 

 probable the Upper Bagshot in Surrey partly represent the Barton 

 beds, since the fossils which occur in them are Barton forms. 

 Prof. Prestwich 3 had previously suggested the same thing. 



We think that we have shown how inadvisable it would be to 



1 Perhaps the most minute comparison between English and Foreign Tertiaries 

 is that made by Prof. C. Mayer, Tableau Synchronistique des Terrains Tertiaires 

 inferieures. Zurich, 1869. 4th edit. Here we find the Mortefontaine beds 

 divided into two divisions, viz. fossiliferous above, which are paralleled with the 

 Long Mead End sands, and unfossiliferous below, placed on a line with the calcaire 

 of St Ouen and unfossiliferous sands of Mortefontaine. We prefer to consider that 

 the unfossiliferous sands of the Senlis and Mortefontaine district are simply part of 

 the Barton sands, and they are separated from the St Ouen limestone by the 

 fossiliferous Mortefontaine bed proper, where developed. There are some miscon- 

 ceptions in this table arising from insufficient distinction between beds in the 

 English localities. Thus the lacustrine [L. Headon] of Hordle seems mixed up with 

 the Upper Headon, Osborne, and Bembridge limestone of Headon Hill. This throws 

 the whole correlation into confusion. The affinity of the Brockenhurst bed is 

 thereby misunderstood. We have endeavoured to rectify this in the table now put 

 forward. 



2 W. H. Herries, On the Bagshot Beds of the Bagshot district, Geog. Mag. xvm. 

 p. 172. 



3 Q. J. G. S. xiii. p. 132. 



VOL. IV. PT. III. 11 



