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XXVIII. Proceedings of Learned Societies. 

 GEOLOGICAL SOCIETY. 

 [Continued from p. 74.] 

 Dec. 21, 1887.— Prof. J. W. Judd, F.R.S., President, in the Chair. 



HP HE following communications were read : — 

 -*- 1. " On the Correlation of some of the Eocene Strata in the 

 Tertiary Basins of England, Belgium, and the North of France." 

 By Prof. Joseph Prestwich, M.A., F.R.S., F.G.S. 



Although the relations of the several series have heen for the 

 most part established, there are still differences of opinion as to the 

 exact relation of the Sable de Bracheux and of the Soissonnais to 

 the English series ; of the Oldhaven Beds to the Woolwich series ; 

 and of the London Clay and Lower and Upper Bagshots to equiva- 

 lent strata in the Paris basin. The author referred to the usual 

 classification of the Eocene Series, and proceeded to deal with each 

 group in ascending order. 



The Calcaire de Mons is not represented in England, but may be 

 in France by the Strontianiferous marls of Meudon. It contains a 

 rich molluscan fauna, including 300 species of Gasteropods, many 

 of which are peculiar, but all the genera are Tertiary forms. The 

 Heersian are beds of local occurrence, and the author sees no good 

 reason for separating them from the Lower Landenian or Tltcmet 

 Sands. He gave reasons for excluding the Sands of Bracheux from 

 this group. Out of 28 Pegwell-bay species, 10 are common to the 

 Lower Landenian, and 5 to the Bracheux Sands, which present a 

 marked analogy with the Woolwich Series. These Sands of Bracheux 

 are replaced in the neighbourhood of Paris by red and mottled clays. 

 Out of 45 species at Beauvais only 6 are common to the Thanet 

 Sands and 10 to the Woolwich Series. Out of 75 species in the 

 Woolwich and Heading Beds 19 occur in the Bracheux Beds, if we 

 add to these latter the Sands of Chalons-sur-Yesles. 



Respecting the Basement Bed of the London Clay (Oklhaven Beds in 

 part), the author would exclude the Sundridge and Charlton fossils, 

 which should be placed on a level with the Upper Marine Beds of 

 Woolwich. He allowed that the former were deposited on an eroded 

 surface, but this involves no real unconformity, whilst the palaeon- 

 tological evidence is in favour of this view, since out of 57 species 

 in the Sundridge and associated beds, only 16 are common to the 

 London Clay. He therefore objected to the quadruple division. 

 Either the Oldhaven should go with the Woolwich or with the 

 Basement Bed. He admitted that the term " Basement Bed" is 

 objectionable, and preferred Mr. Whitaker's term for the series, as 

 he would limit it. 



The Lower Bagshot Sands the author would call " London Sands " 

 whose Belgian equivalent is the Upper Ypresian, and the French 

 the Sands of Cuise-de-la-Motte, forming the uppermost series of 

 the Lower Eocene. A group of fossils has been discovered in the 



