90 
LOWER CHALK. 
The lower beds of the flinty chalk, in Sonth- 
street, contain detached crystals of snlphnret of 
iron, remarkable for their neatness and elegant 
figure. They are usually regular octaedrons, 
having their planes studded with small quadran- 
gular pyramids ; but some examples occur in 
which the solid angles are replaced by quadrangu- 
lar planes, forming a crystal with fourteen sides. 
LOWER CHALK.* 
The absence of siliceous nodules, and the supe- 
rior hardness of the chalk, distinguishes this de- 
posit from that which lies above it. 
Its colour is of a light grey, enclosing masses of 
pure white. It forms the low elevations at the 
foot of the Downs ; and, as the situations it occupies 
are generally easy of access, a considerable number 
of quarries have been opened in difterent parts of 
* In some parts of England the chalk admits of a more minute 
division. The cliffs in the vicinity of Dover, described by Mr. Phillips 
(Geological Transactions, vol. v. p. 18.), are separated by that gentle- 
man into the following, viz. : — 
I. Chalk with numerous flints, 350 feet thick ; which is subdivided 
into — 
1. A bed with few organic remains. 
2. Chalk with interspersed flints, consisting chiefly of organic 
remains, in which numerous flints of peculiar forms are 
interspersed, and a few beds of flint. 
II. Chalk with a few flints: this stratum is about 130 feet thick. 
III. Chalk without flints, 140 feet thick, consisting of — 
1. A stratum containing very numerous and thin beds of 
organic remains, 00 feet thick. 
2. A bed 50 feet thick, with few organic remains. 
IV. Grey chalk, estimated at 200 feet in thickness. 
