UPPER EOCENE (bARTON AND UPPER BAGSHOT FORMATIONS). 579 



distinctly Eocene in facias that the flora of Bournemouth, which is 

 at the base of the Middle Eocene, may be said to be the typical flora 

 of the Oligocene in Europe. 



The Upper Eocene in England will, according to our views, com- 

 prise the Barton Series and the Upper Bagshot Series, the inferior 

 limit being the Bracklesham, and the superior limit the Headon 

 Beds. We have gathered conclusive evidence that the Upper Bag- 

 shot Series of the London basin is, to a large extent, the equivalent 

 of the Barton Series of the Hampshire basin, and represents, indeed, 

 rather its lower than its upper bed. This fact, again, has rendered 

 revision necessary, and the classification which, we submit, best 

 meets the requirements is the following: — 



Upper Eocene. 

 London Basin. Hampshire Basin. 



Upper Bagshot Series. | Unrepresented. | ^^^^^,^^.;Beds. 



The base-line of the formation is, it must be confessed, not too 

 well marked, but it almost coincides with the disappearance of 

 J^ummulites in our area, and with a considerable change in the 

 character of the fauna, through the disappearance of a number 

 of subtropical forms. Deposition was so continuous here during 

 the Eocene time that it is not always easy to draw strongly 

 marked lines of division, for such, in this case, would only occur 

 where there had been great changes of level, or where an "arm of 

 the sea became landlocked and dry. It would thus be perfectly 

 easy, say, to distinguish between early Pliocene deposits in Italy 

 and those forming in historic times along the margin of the 

 Adriatic ; but if the whole basin of the Adriatic were upheaved, and 

 escarpments cut through it, as in Hampshire, it might be very diffi- 

 cult to draw satisfactory lines between the Pliocene and the recent 

 beds. 



Literature. — We have not compiled any list of works on the 

 Upper Bagshot Beds, as those of importance are referred to further 

 on. The splendid preservation and abundance of the fossils in the 

 Barton Beds attracted the attention of Mr. Brander, Curator of 

 the British Museum, and, in 1766, a work upon them was so admi- 

 rably illustrated that all the 85 species of MoUusca described in it 

 by Dr. Solander can readily be identified. Professor Prestwich 

 communicated descriptions of the Barton Beds to this Society in 

 1847-1854 ; and a Geological Survey Memoir on the Isle of Wight, 

 dealing with the Barton Beds at Alum and Whitecliff Bays, appeared 

 in 1862. Prof, Prestwich also described the Bagshot Beds of the 

 London area in 1847*, placing the Upper Sands provisionally some- 

 where between the Bracklesham and Headon Series ; and Trimmer 

 included both the Barton and Bracklesham Beds in the Middle 

 * Quart. Journ. Geol. Soc. vol. iii. p. 384. 



