144 Mr Tawney, On the Upper Bar/shot Sands of [Nov. 28, 



1859. H. W. Bristow. Explanation of Sections across the Isle of 

 Wight, illustrative of Geological Map, Sheet No. 10. In this explana- 

 tion, and in the legend to the Survey Vertical Sections, the above facts 

 collected by the Survey are repeated. 



1862. H. W. Bristow. The Geology of the Isle of Wight. Mem. 

 Geol. Surv., Sheet 10, pp. 50 — 52. A fuller account of the Survey re- 

 sults than given in Forbes' Memoir or Appendix to it. The casts of 

 bivalves found in these sands at White Cliff Bay are said to be Cardium, 

 Tellina, Panopcea. 



1864. A. Von Koenex. On the Correlation of the Oligocene de- 

 posits of Belgium, Northern Germany and the South of England. 

 Q. J. G. S. xx. p. 97. In a note to p. 99 this sand at Headon Hill is 

 classed with the Barton beds, because at Hordwell it contains many 

 characteristic Barton shells, Oliva Branderi, &,c. 



From the excellent descriptions of the late Searles Wood and 

 Marchioness of Hastings, it will be seen that the sands in question 

 are from fifteen to twenty feet in thickness. Our experience agrees 

 too with former descriptions, that the fossils are confined to the 

 upper part of the sands, where they are so crowded together that 

 sometimes the shells contribute more to the substance of the bed 

 than the sand. The Gyrena and Melania are the most abundant, 

 after them perhaps comes the Gerithium pleurotomoides. 



The object of the present communication is to discuss the 

 affinities of the deposit with a view to the classification, and also 

 to glance at its equivalent in the Paris basin. 



With regard to the actual position of the sand below the fresh- 

 water Lower Headon all observers are agreed, and its more marine 

 character in contrast with these was insisted on by Searles Wood. 



We are confronted however with less unanimity when we con- 

 sider the question of its classification in the Tertiary system — 

 whether it should be placed in the Middle or Upper Eocene, &c. 



There are two views to be noticed. Even so early as 1838 

 D'Archiac was inclined to classify it with the marine [Barton] beds 

 below, rather than with the freshwater deposits above. 



Forbes and the Geological Survey most 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, the designation of some previous authors) sands. Forbes 

 noticing its containing apparently Barton species at White Cliff 

 Bay presents to us thus its affinity to Barton beds. Dumont 1 

 may be said to have favoured a similar classification. 



An opposite view is that lately advanced by Prof. Judd 2 ; in dis- 

 cussing the development of the Headon Hill beds, he writes [p. 169], 



1 Loc tit. pp. 37, 48. 



2 On the Oligocene Strata of the Hampshire Basin. Q. J. G. S. xxxvi. (1880), 

 p. 137. 



