II.  EOCENE BEDS OF THE PARIS BASIN.—­The Eocene strata are very well developed in the neighbourhood of Paris, where they occupy a large area or basin scooped out of the Chalk.  The beds of this area are partly marine, partly freshwater in origin; and the following table (after Sir Charles Lyell) shows their subdivisions and their parallelism with the English series:—­

GENERAL TABLE OF FRENCH EOCENE STRATA.

UPPER EOCENE.

French Subdivisions. English Equivalents.
A. 1.  Gypseous series of Mont 1.  Bembridge series. 
Montmartre. 
A. 2.  Calcaire silicieux, or 2.  Osborne and Headon series. 
Travertin Inferieur. 
A. 3.  Gres de Beauchamp, or 3.  White sand and clay of
Sables Moyens.  Barton Cliff, Hants.

MIDDLE EOCENE.

B. 1.  Calcaire Grossier. 1.  Bagshot and Bracklesham beds. 
B. 2.  Soissonnais Sands, or 2.  Wanting. 
Lits Coquilliers.

LOWER EOCENE.

C. 1.  Argile de Londres at base 1.  London clay.
of Hill of Cassel, near
Dunkirk. 
C. 2.  Argile plastique and 2.  Plastic clay and sand with
lignite. lignite (Woolwich and Reading
series). 
C. 3.  Stables de Bracheux. 3.  Thanet sands.

III.  EOCENE STRATA OF THE UNITED STATES.—­The lowest member of the Eocene deposits of North America is the so-called “Lignitic Formation,” which is largely developed in Mississippi, Tennessee, Arkansas, Wyoming, Utah, Colorado, and California, and sometimes attains a thickness of several thousand feet.  Stratigraphically, this formation exhibits the interesting point that it graduates downwards insensibly and conformably into the Cretaceous, whilst it is succeeded uncomformably by strata of Middle Eocene age.  Lithologically, the series consists principally of sands and clays, with beds of lignite and coal, and its organic remains show that it is principally of fresh-water origin with a partial intermixture of marine beds.  These marine strata of the “Lignitic formation” are of special interest, as showing such a commingling of Cretaceous and Tertiary types of life, that it is impossible to draw any rigid line in this region between the Mesozoic and Kainozoic systems.  Thus the marine beds of the Lignitic series contain such characteristic Cretaceous forms as Inoceramus and Ammonites, along with a great number of Univalves of a distinctly Tertiary type (Cones, Cowries, &c.) Upon the whole, therefore, we must regard this series of deposits as affording a kind of transition between the Cretaceous and the Eocene, holding in some respects a position which may be compared with that held by the Purbeck beds in Britain as regards the Jurassic and Cretaceous.

The Middle Eocene of the United States is represented by the Claiborne and Jackson beds.  The Claiborne series is extensively developed at Claiborne, Alabama, and consists of sands, clays, lignites, marls, and impure limestones, containing marine fossils along with numerous plant-remains.  The Jackson series is represented by lignitic clays and marls which occur at Jackson, Mississippi.  Amongst the more remarkable fossils of this series are the teeth and bones of Cetaceans of the genus Zeuglodon.