Ch. XVI.] UPPER EOCENE FORMATIONS. 281 



freshwater formations, which have been already spoken of as Lower 

 Miocene, but their superficial extent is insignificant, except in the 

 Paris basin between the Seine and the Loire. 



UPPER EOCENE FORMATIONS, ENGLAND. 



The following table will show the order of succession of the strata 

 found in the Tertiary areas, commonly called the London and Hamp- 

 shire basins. (See also Table, p. 103, et seq.) 



LOWER MIOCENE. „,, . , 



Thickness. 



Hempstead beds, Isle of Wight, see above, p. 239, - - 170 feet. 



UPPER EOCENE. 



A. 1. Bembridge Series — North coast of Isle of Wight, - 120 



A. 2. Osborne or St. Helen's Series — ibid., - 100 



A. 3. Headon Series— Isle of Wight, and Hordwell Cliff, Hants, - 170 



A. 4. Barton Clay, Isle of Wight, and Barton Cliff, Hants, - - 300 



• MIDDLE EOCENE. 



B. Bagshot and Bracklesham Sands and Clays — London and Hants 



basins, ------- 700 



LOWER EOCENE. 



C. 1. London Clay proper and Bognor beds — London and Hants 



basins, - - - - - - - 350 to 600 



C. 2. Plastic and Mottled Clays and Sands — London and Hants 



basins, ------- 100 



C. 3. Thanet Sands — Eeculvers, Kent, and Eastern part of London 



basin, ------- 90 



The true relative position of the Hempstead beds and of the Bem- 

 bridge, A. 1, and the Osborne or St. Helen's series, A. 2, were not 

 made out in a satisfactory manner till Professor Forbes studied them 

 in detail in 1852. The true place of the Bagshot sands, B., and of 

 the Thanet sands, C. 3, was first accurately ascertained by Mr. Prest 

 wich in 1847 and 1852. 



UPPER EOCENE, ENGLAND. 



Bembridge series, A. 1. — These beds are about 120 feet thick, and, 

 as before stated (p. 239), are conformable with the Hempstead beds, 

 near Yarmouth, in the Isle of Wight. They consist of marls, clays, 

 and limestones of freshwater, brackish, and marine origin. Some of 

 the most abundant shells, as Cyrena semisiriata var., and Paludina 

 lenta, fig. 176, p. 24tf, are common to this and to the overlying Hemp- 

 stead series ; but the majority of the species are distinct. The fol- 

 lowing are the subdivisions described by Professor Forbes : — 



