Cir PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



have already said that it would be no easy matter to work out such 

 a problem, as regards the recent, or now-forming deposits, were we 

 furnished only with the data afforded by the relics of their organic 

 inhabitants. The labours of Mr. Prestwich in this line we have 

 already dwelt upon ; and in this posthumous work we have set before 

 us the most recent of those of Edward Forbes^ valuable at once for 

 the practical matter it contains, and for the further proofs it affords 

 of what we might have expected in the higher and most philoso- 

 phical speculations of our science, had our lamented friend been 

 still spared to us. 



The whole series of Eocene or Lower Tertiaries of the Isle of 

 Wight is thus stated in a descending order : — Hempstead Series, 

 Bembridge Series, Osborne Series, Headon Series, Barton Series, 

 Bracklesham Series, Lower Bagshot Series, London Clay, and sub- 

 jacent members of the Lower Eocene. By comparing this list with 

 those previously published, it will be observed that Professor Forbes 

 had discovered a group of sands, marls, and clays, to which he 

 gave the name of Osborne Series, from their occurrence within the 

 royal demesne, and that he intercalated it between the Bembridge 

 and Headon Series. 



In the distribution of these groups a nearly similar arrangement 

 is adopted to that proposed by Mr. Prestwich, as the Bracklesham 

 and Barton Beds are associated together as the Middle Eocene, just 

 as Mr. Prestwich considers them to constitute, with the Lower Bag- 

 shot Sands, the Paris Tertiary Group ; the Headon Series, Osborne 

 Series, and Bembiidge Series constituting the Upper Eocene. As 

 on the first reading of his paper by Mr. Prestwich, the Paris 

 Group was designated Middle Eocene, the terms Middle Eocene and 

 Paris Group appear synonymous, and in truth in any attempt to 

 classify these beds in groups the organic approximation between the 

 Bracklesham and Barton Series in England, and between the Cal- 

 caire Grossier and Sables Moyens in France, must render it very 

 difficult to form any natural separation betAveen them. For draw- 

 ing the upper limit of the Eocene, as Professor Forbes has done, 

 so as to exclude from England all Miocene deposits, very strong 

 reasons are adduced ; these lines of demarcation will, however, 

 vary according to the view taken by different geologists * of the 

 relative importance of the organic evidence made use of. This work 

 forms part of the publications of the Geological Survey, and Mr. 

 Austen has been assisted in several parts of it by Mr. Salter and 

 Mr. Bristow, members of that establishment, as well as by Mr. 

 Morris and Mr. Jones. The ample tabulated, or as they might 

 be properly called, statistical details, on which the several geological 

 deductions have been founded, mark most strongly the care which 

 as editor Mr. Austen has bestowed upon the work ; and it is only 



* During the progress of this address through the press, the Supplement to 

 the 5th edition of the ' Manual of Elementary Geohigy ' has heen pubhshed, in 

 which Sir C. Lyell separates the Barton Clay and its equivalents, the Sables 

 Moyens and 1-aeken beds, from the Middle Eocene, leaving the Bracklesham Sands 

 as their only English representative. 



