1881.] Hordwell Cliffs, Hampshire. 147 



Beauchamp representing our Barton beds : above this comes the 

 Calcaire de St Ouen, mainly freshwater. Connected with St Ouen 

 limestone are sands and marls, with abundance of G. concavum, Sow., 

 a layer near the base, and another at the top. It is plain then 

 that the St Ouen period represents our Headon series, only that 

 our beds are thicker. Moreover, in the Hampshire basin the fresh- 

 water and marine conditions in the Headon series are not in the 

 same order as in the St Ouen beds. With us the marine facies 

 with G concavum comes between the two freshwater Lower and 

 Upper Headon deposits, respectively 100 and 50 feet thick. Near 

 Montjavoult M. Munier-Chalmas represents the bulk of the fresh- 

 water limestone, in the centre between two deposits with this 

 Cerithium. In France therefore the G. concavum zone is not 

 connected with the G. pleurotomoides zone but comes distinctly 

 above it. The Mortefontaine sand with G. pleurotomoides is classed 

 by French authorities as the upper part of the " Sables de Beau- 

 champ" or Barton beds. The fossils of the Paris basin Tertiaries 

 are usually so much better preserved than in equivalent English 

 beds, and the faunas have been so much better worked out in 

 France — partly no doubt from this circumstance, and partly from 

 the different zones being found frequently in different localities — 

 that we may derive great assistance in classifying our beds from 

 comparison with the classical series of the Paris basin. 



In the Table following an attempt is made to correlate the 

 beds on either side of the Channel. The thickness of the English 

 beds is given as a guide to those who have not actually visited 

 them, and we hope these details may aid in comparison with 

 foreign equivalents 1 . In the French series some of the minor 

 subdivisions are omitted. The line between Miocene and U. Eo- 

 cene 2 is drawn according to Lyell, a method of classification adopted 



1 As an instance of misconceptions which it is desirable to clear up may be 

 mentioned the following ; Prof. Sandberger [Suesswasser Conchy lien, p. 312 note] 

 citing Melania turritissima as occurring at Hordwell and Hamstead, intimates that 

 these beds are of the same horizon. It will be seen by the Table that about 250 

 feet of beds intervene. 



2 Though we do not wish to enter into the question here of the utility of the 

 term Oligocene, we may remark that we consider tbe fine sections of the Isle of 

 Wight show that it is less applicable to the English Tertiaries than the older and 

 more classical division into Eocene, &c. This is shown too by the fact that foreign 

 authorities who have attempted to apply tbis term in the correlation of English 

 with German beds are not agreed about the boundaries. Thus Von Koenen makes 

 the M. Headon, including the Brockenhurst bed, the equivalent of the German 

 L. Oligocene. But Prof. C. F. Sandberger (Land und Suesswasser Conchylien <Ier 

 Vorwelt, p. 198) makes the St Ouen limestone or Cerithium concavum zone the 

 top of the Upper Eocene, so that the Lower Oligocene boundary is shifted higher 

 up, and our M. Headon is Upper Eocene in this scheme. In other words the break 

 between Oligocene and Eocene is an unnatural one, and the introduction of the 

 term in our opinion obscures the affinities between the members of the English 

 series. 



