276 
EOCENE PERIOD. 
[Ch. XX. 
Basin of the Cotentin, or Valognes. — The strata in the 
environs of Valognes, in the department of La Manche, consist 
chiefly of a coarse limestone resembling the calcaire grossier of 
Paris, of which M. Desnoyers has given an elaborate descrip- 
tion. It is occasionally covered with a compact fresh-water 
limestone alternating with fresh-water marls. In these Eocene 
strata more than 300 species of fossil shells have been disco- 
vered, almost all identical with species of the Paris basin. (See 
Tables, Appendix I.) Superimposed upon the Eocene strata 
of this basin is a newer marine deposit, extending over a 
limited area, the fossils of which agree with those of the Faluns 
of the Loire*. Here, therefore, the geologist has an opportu- 
nity of observing the superposition of the Miocene deposits 
upon those of the age of the Paris basin. 
Rennes. — Several small patches, also, of marine strata, have 
been found by M. Desnoyers, in the neighbourhood of Rennes, 
which are characterised by Eocene fossils and repose on ancient 
rocks, as will be seen in the map. 
Basin of Belgium, or the Netherlands. — The greater part of 
the tertiary formations of the Low Countries consist of clay 
and sand, much resembling those of the basin of London, after- 
wards to be described. The fossil shells, also, are of the same 
species, 49 of which will be found referred to by M. Deshayes, 
in the tables, Appendix I. 
Aix, in Provence. — The tertiary strata of Aix and Fuveau 
in Provence are of great thickness and extent, the lower mem- 
bers being remarkable for containing coal grit and beds of 
compact limestone, such as we only find in England in 
ancient secondary groups. Yet these strata are for the most 
part of fresh-water origin, and contain several species of Eocene 
shells, together with many which are peculiar to this basin. It 
would require a fuller comparison than has yet been made of 
the fossil remains of Aix and Fuveau, before we can determine 
with accuracy the relative age of that formation. Some of the 
plants seem to agree with those of the Paris basin, while many 
* Desnoyers, Mem. dela Soc. d'Hist. Nat. de Paris, 1825. 
