222 EOCENE STEATA IN FRANCE. [Cn. XVI. 



Isle of Wight and Hampshire is often seen in actual contact with the 

 chalk, constituting in such places the lowest member of the British Eo- 

 cene series. But in other points another formation of marine origin, 

 characterized by a somewhat different assemblage of organic remains, has 

 been shown by Mr. Prestwich to intervene between the chalk and the 

 Woolwich series. For these beds he has proposed the name of " Thanet 

 sands," because they are well seen in the Isle of Thanet, in the northern 

 part of Kent, and on the sea-coast between Heme Bay and the Reculvers, 

 where they consist of sands with a few concretionary masses of sandstone, 

 and contain among other fossils Pholadomya cuneata, Cyprina Morrisii, 

 Corbula longirostris, Scalaria Boiverhankii, &c. The greatest thickness 

 of these beds is about 90 feet. 



FRENCH MIDDLE EOCENE FORMATIONS. 

 GENERAL TABLE OF FRENCH EOCENE STRATA. , 



A. UPPER EOCENE [Lozver Miocene of many French authors.) 



English Equivalents. 



A. Calcaire de la Beauce, or upper fresh- ) 



water, see p. 184, and Gres de Fon- S Hempstead series, see p. 192. 

 tainebleau, (fee. ) 



B. MIDDLE EOOENE. 



B. 1. Gypseous series and Middle fresh- ) ■„ i -i • m^ 



•^-, 1-1 . }• Bembrido:e series, p. 194. 



water calcaire lacustre moyen. ) ® ' ^ 



B. 2. Calcaire siliceux, (in part contem- 1 



poraneous with the succeeding >• Lower part of the Bembridge series, 

 group?) 3 



o /-( ^ J !-> I, o 1,1 HT ( Osborne series, and upper and middle 



B. 3. Gres de Leauchamp, or Sables Mo- J ^^ Headon series, Isle o! 



y«"^- ( Wight. 



. TT n 1 • /-I • //-( -1 \ ( Headon Hill sands. Barton, Upper 



B. 4. Upper Calcaire Grossier (Cailasse)3 ^^^ ^^^^ ^^^ ^^ Bracklesham 



and Middle Calcaire Grossier. i -, ?^ '■ 



B. 5. Lower Calcaire Grossier or Glau- L^.^^^^^^^^^^^^^ ^^^^^ 

 come Grossiere. ) 



( Lower Bagshot. Intermediate in age 

 E. 6. Soissonnais Sans or Lits coquilliers. •< between the Bracklesham beds and 



( London Clay. 



C. LOWER EOCENE. 



.,,,.. . T -^ ( Plastic clay and sand, with lignite 



c. Argile plastique et lignite. j (Woolwich and Reading series.) 



The tertiary formations in the neighborhood of Paris- consist of a 

 series of marine and freshwater strata, alternating with each other, and 

 filling up a depression in the chalk. The area which they occupy has 

 been called the Paris basin, and is about 180 miles in its greatest 

 length, from north to south, and about 90 miles in breadth, from east 

 to west (see Map, p. 195). MM. Cuvier and Brongniart attempted, in 

 1810, to distinguish five different groups, comprising three freshwater 



