92 
LOWER CHALK. 
marl. The strata exhibit decided proofs of having 
suffered considerable displacement ; they are in- 
clined obliquely toward the north, at an angle of 
from 20 ° to 30°, their planes being depressed towards 
the west. Northward from this spot, at the dis- 
tance of about 300 yards, the upper chalk is ex- 
posed in the pit of Messrs. Hillman, in South- 
street, and here the strata are slightly inclined to 
the south. The hill in which both these quarries 
occur presents a smooth unbroken outline, con- 
veying no indication of the changes that have 
taken place beneath its surface. 
MINERALS. 
1. Sulphuret of iron is the only metallic sub- 
stance that occurs in the lower chalk ; and of this 
mineral some elegant crystals, of a reddish or yel- 
lowish brown colour, have been discovered, in the 
quarries at the foot of Mailing Hill. 
They consist of nine or ten quadrangular co- 
lumns, formed of octaedrons piled upon each 
other ; these proceed from one common centre, 
and each terminates in a quadrangular pyramid. 
The lower chalk, near Beachy Head, contains 
small cylindrical masses of pyrites of a steel grey 
colour, that possess a very brilliant lustre ; their 
surface is generally invested with pyramidal crys- 
tals, having their solid angles replaced by quadran- 
gular planes. 
