EOCENE PERIOD. 549 



of sands, clays, and gravels, and attaining a very considerable 

 thickness (Bagshot and Bracklesham beds). The superior 

 portion of the Middle Eocene of Britain, on the other hand, 

 consists of deposits which are almost exclusively fresh-water 

 or brackish-water in origin (Headon and Osborne series). 



The chief Continental formations of Middle Eocene age are 

 the " Calcaire grossier " of the Paris basin, and the "Num- 

 mulitic Limestone " of the Alps. 



III. UPPER EOCENE. If the Headon and Osborne beds of 

 the Isle of Wight be placed in the Middle Eocene, the only 

 British representatives of the Upper Eocene are the Bern- 

 bridge and Hempstead beds though the latter are regarded 

 by Sir Charles Lyell as being of Lower Miocene age. These 

 strata consist of limestones, clays, and marls, which have for 

 the most part been deposited in fresh or brackish water. 



IV. 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 fresh- 

 water 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. I. Gypseous series of Mont- I. Bembridge series. 



martre. 



A. 2. Calcaire silicieux, or Tra- 2. Osborne and Headon series. 



vertin Inferieur. 



A. 3. Gres de Beauchamp, or 3. White sand and clay of Barton 



Sables Moyens. Cliff, Hants. 



MIDDLE EOCENE. 



B. I. Calcaire Grossier. I. Bagshot and Bracklesham beds. 



B. 2. Soissonnais Sands, or Lits 2. Wanting. 



Coquilliers. 



LOWER EOCENE. 



C. I. Argile de Londres at base of I. London Clay. 



Hill of Cassel, near Dun- 

 kirk. 



C. 2. Argile plastique and lignite. 2. Plastic clay and sand with lig- 

 nite (Woolwich and Reading 

 series). 

 C. 3. Sables de Bracheux. 3. Thanet sands. 



V. EOCENE STRATA OF THE UNITED STATES. In North 

 America, Lower Eocene Rocks are extensively developed at 



