162 J. L. LOBLET — THE EOCENES OF ENGLAND 



the county of Hants and the northern part of the Isle of Wight, 

 is known by the name of the Hampshire Basin. No beds of 

 Eocene age occur in Great Britain outside these areas. The 

 physical features of the Eocene districts of England are not striking, 

 the elevations being inconsiderable, and the valleys broad ; but a 

 luxuriant growth of timber trees of large size gives a rich ap- 

 pearance to a great portion of each area, while utterly barren wastes 

 occupy a by no means inconsiderable portion of the London Basin. 



But though the single name Eocene has been given to the whole 

 of the lower division of the Tertiaries, this group of strata is by no 

 means uniform either lithologically or palaiontologically. On the 

 contrary, it consists of siliceous, calcareous, and argillaceous beds, 

 some marine, some estuarine, and some freshwater, with, as a con- 

 sequence, markedly distinct assemblages of fossils. There are 

 therefore abundant grounds for distinguishing the various beds by 

 different names, and thus it is that the term the Eocenes of England 

 is used. 



The following are the various divisions of the Eocene group of 

 British strata (in descending order) : — 



Bembridge Series. 



Osborne or St. Helen's Beds. ] Upper Eocene. 



Headon Series. 



Upper Bagshot Beds. 



Bracklesbam and Barton Beds. ] Middle Eoceni 



Lower Bagshot Beds. 



London Clay and Bognor Rock. 

 Oldhaven Beds. 



Woolwich and Reading Series. 

 Thanet Sands. 



Loweu Eocene. 



The Lower Eocenes. 



The Thanet Sands. — Above tlie Chalk in the London Basin we 

 find a series of beds chiefly of sand extending from the east of 

 Thanet to a little west of London, lying chiefly south of the Thames. 

 To these beds the name Thanet Sands has been given. Besting 

 immediately upon the Chalk, the surface of which is irregularly 

 eroded, lies a bed of large flints, unworn, but all covered with a 

 green coating which has been ascertained to be silicate of iron. 

 These flints are obviously Chalk flints, and since thoy are unworn, 

 it is concluded that they, being siliceous and therefoi-e insoluble 

 bodies, have been left by the removal of a bed of Clialk, not by 

 running water, but by its solution by carbonated water which has 

 percolated through overlying beds, and that the flints are a measure 

 of the amount of chalk so removed. The bed of green-coated 

 flints, or Bull Head bod, with argillaceous matter, forms the base 

 or lowest bed of the Tlianot Sands, which are divisible in the 

 typical locality of Pegwell Bay into Ave distiiut beds. Tlu^y 

 are described in detail by Mr. Wliitaker in his pa})er " On the 

 Lower London Tertiaries of Kent," in the ' tiuarterly Journal of 



