J. S. Gardner — Revision of the British Eocenes. 467 



temporaneous sea-deposits have to be separated from them. The 

 grouping adopted is in some cases quite artificial, and the existing 

 divisions do not even approximately correspond in value, either 

 stratigraphically, or as measures of the physical or biological changes 

 that took place during the Eocene period. 



The suppression of the term Upper Eocene, applied b}'^ Lyell and 

 all the older authors to the classic Fluvio-Marine Series of the Isle of 

 "Wight, leaves our English group — and this I believe applies equally 

 to the foreign Eocenes — almost without an Upper division. Under 

 these circumstances, I submit that the following arrangement presents 

 a more natural and useful classification than that now in use. 



UiiTier Eocene \ Upper Bagshot. 



upper J^ocene j Middle Bagshot. 



Middle Eocene | 



Lower Bagshot. 

 London Clay. 



I Oldbaven Series. 



Lower Eocene < "Woolwich and Eeading Series. 



( Thanet Series. 



If an Oligocene formation is not recognized, there will be no 

 occasion for any rearrangement — while the change introduces no 

 new names, and scarcely affects the very exact and admirable work 

 of Prof. Prestwich and the Geological Survey. 



All these divisions are well marked in this country, and are 

 characterized by groups of fossils peculiar to each, and as they are 

 perhaps better developed here as a series than anywhere on the 

 Continent, we may well trust that the modified classification they 

 so clearly require to reduce them to a natural system, should be 

 adopted in countries where the sequence is possibly more difficult to 

 trace than in our own. 



The Lower Eocene group in the proposed system is singularly 

 homogeneous, and embraces all the beds below the London Clay. 

 There is nothing, moreover, so far as I am aware, to prevent the 

 still older beds of France and Belgium — as far down as the Calcaire 

 de Mons — from being grouped with it. 



This group consists of sediments of marine, littoral, estuarine and 

 freshwater origin. They ai-e roughly classified as Thanet Beds, 

 Woolwich and Eeading Beds, and Oldhaven Beds. The Thanet Beds, 

 developed almost exclusively in Kent, are marine, though certainly 

 deposited close to shore. They are best seen between Eeculvers and 

 Heme Bay, and a minute study of the l:)eds there tends to show that 

 the upper parts of the section, divided off by the Survey as Woolwich 

 and Eeading and Oldhaven Beds, are but minor subdivisions of a 

 single and continuous formation. This great marine deposit is trace- 

 able westward in the ancient beaches known as Oldhaven deposits, 

 which form a zone reaching to the south and east of London as far 

 as Croydon. It is obvious that such extensive tracts of beach or 

 shoals could only be produced by continued retrogression of the 

 sea, and the beaches furthest inland would be the oldest. There is 

 absolutely no reason that I see at present why the vast accumulations, 

 of shingle at Bickley and elsewhere should not be contemporaneous 



