2V0 
ELEMENTS OE GEOLOGY. 
UPPER EOCENE FORMATIONS OF FRANCE. 
The tertiary formations in the neighborhood of Paris con¬ 
sist of a series of marine and fresh-water 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. MM. 
Cuvier and Brongniart attempted, in 1810, to distinguish 
five different groups, comprising three fresh-water and two 
marine, which were supposed to imply that the waters of 
the ocean, and of rivers and lakes, had been by turns admit¬ 
ted into and excluded from the same area. Investigations 
since made in the Hampshire and London basins have rather 
tended to confirm these views, at least so far as to show that 
since the commencement of the Eocene period there have 
been great movements of the bed of the sea, and of th-e ad¬ 
joining lands, and that the superposition of deep-sea to shal¬ 
low-water deposits (the London clay, for example, to the 
Woolwich beds) can only be explained by referring to such 
movements. It appears, notwithstanding, from the research¬ 
es of M. Constant Prevost, that some of the minor alternations 
and intermixtures of fresh-water and marine deposits, in the 
Paris basin, may be accounted for without such changes of 
level, by imagining both to have been simultaneously in 
progress, in the same bay of the same sea, or a gulf into 
which many rivers entered. 
Gypseous Series of Montmartre (A. l. Table, p. 252).—To 
enlarge on the numerous subdivisions of the Parisian strata 
would lead me beyond my present limits; I shall therefore 
give some examples only of the most important formations. 
Beneath the Gres de Fontainebleau, belonging to the Lower 
Miocene period, as before stated, we find, in the neighbor¬ 
hood of Paris, a series of white and green marls, with subor¬ 
dinate beds of gypsum. These are most largely developed 
in the central parts of the Paris basin, and, among other 
places, in the hill of Montmartre, where its fossils were first 
studied by Cuvier. 
The gypsum quarried there for the manufacture of plaster 
of Paris occurs as a granular crystalline rock, and, together 
with the associated marls, contains land and fluviatile shells, 
together with the bones and skeletons of birds and quadru¬ 
peds. Several land-plants are also met with, among which 
are fine specimens of the fan-palm or palmetto tribe {Flabella- 
ria). The remains also of fresh-water fish, and of crocodiles 
and other reptiles, occur in the gypsum. The skeletons of 
