40 
THE CRETACEOUS ROCKS OF BRITAIN. 
on account of the number and variety of the fossils which it con¬ 
tains. Mr. Price describes it as a soft chalk-marl of a light grey 
colour, mottled and striped with darker grey, and, as it is soft 
enough to be cut with a knife, its fossils can be easily extracted. 
It is sometimes known as the “ cast-bed/’ 
This bed rises above high water level at a point about two miles 
east of Folkestone, and the place is marked by the issue of a strong 
perennial spring, which is. known as Lydden Spout. This out¬ 
flow of water is evidently due to the impermeability of this com¬ 
pact argillaceous mail which forms a floor under the hill behind, 
and holds up the water which has percolated through the super¬ 
incumbent chalk. 
Small nodules of iron pyrites occur in this bed which have a 
smooth, bright, silvery surface, and thus differ from the nodules 
occurring in other beds. 
Although this bed is rich in fossils, and has yielded many species 
which have not yet been found in the beds below, yet the fauna is 
essentially that of the Chalk Marl or zone of Ammonites varians, 
and most of the Cephalopoda which occur in it are also found in 
Bed 2. What gives it, however, a distinctive character is the number 
of Gastropoda it contains, no fewer than nineteen species having 
been recorded by Mr. Price. There are also many small Brachiopods 
Rhynchonella mantel liana and Terebratulina noclulosa being 
especially common. 
Bed 5. -This, together with the succeeding Beds 0, 7 and 8, make 
up the division which was numbered VI. by Mr. Price. Above the 
band which has been indicated as the “ cast-bed ” of Price there 
are 19 feet of grey marly chalk, which we are inclined to class as 
“Chalk Marl'’ rather than “Grey Chalk.'’ The abundance of 
Rhynclionella man fell la inf and the occurrence of Am. [Scldoenhachia] 
varians link it to the beds below rather than to those above. 
The lowest 2 feet consist of rather firm grey chalk less marly 
than the remainder. 
Above this are 7 feet of dark grey marly chalk containing frag¬ 
ments of Am. varians. 
The remaining 10 feet consist of rather soft grey marly chalk 
containing Rhynclionella mantelliana, Rh. Martini, Kin.gena 
lima, and other fossils. 
There is no definite demarcation between this and No. 6. 
Zone of Holaster subglobosus. 
Bed 6. —This subdivision consists of what may legitimately be 
called “grey chalk,” in contrast with the marly chalk below and 
the whiter chalk above. It is massive and blocky, breaking rather 
along curvilinear joint-planes than along definite lines of bedding; 
