PLASTIC CLAY. 
63 
miles west of Arundel ; and also on the declivity 
of the hill by which the Binstead and Chichester 
road descends into Arnndel. 
The country around Chichester has a foundation 
of chalk, with a subsoil of fine red gravel, and 
])ebbles, mixed with sand, loam, and chalk rubble. 
Furrows and wells in the chalk, filled with these 
materials, are commonly observable in the quarries 
near that city. 
From the immense quantity of marine, and the 
almost entire exclusion of freshwater shells, it is 
manifest that of the straUi of Castle Hill, the beds 
below the blue clay, with cerethites, can alone be 
considered as analogous to the freshwater form- 
ation of the Paris Basin. In the Geo^rap/u'e Mi- 
m'ralop'ique des Environs de Paris, the Plastic clay 
formation is divided as follows : — 
{ Argile plastique. 
Lignites. 
Premier gres. 
From the description of the strata around Paris, 
in the celebrated work above referred to, it ap- 
pears, that although its illustrious authors consider 
the Plastic clay as a freshwater formation, yet, in its 
up})er division, marine shells predominate. That, 
generally, in the beds resting immediately upon 
the chalk, organic remains do not occur* ; that, 
in the middle portion, freshwater shells (Planorbis, 
Lymmea, Paludina, Cyrena, &c.) and vegetable 
remains, commonly prevail ; and that if marine 
* “ C’est ordinairement dans les parties inferieures que se trouve la 
veritable argile 2)lasfi(jHc; I’argilc pure, infusible, ne renfermant aucun 
debris organique.” — Geog. Min. |). 
