ELEMENTS OF GEOLOGY. 
ai6 
Fig:. 292. den, sometimes prodncing, like plates of 
mica, a thin lamination (see Fig. 292). 
Hastings Sands. —This lower division 
of the Wealden consists of sand, sand¬ 
stone, calciferous grit, clay, and shale; 
the argillaceous strata, notwithstanding 
Weald clay wuhCyprides. t^e name, predominating somewhat over 
the arenaceous, as will be seen by refer¬ 
ence to the following section, drawn up by Messrs. Drew and 
Foster, of the Geological Survey of Great Britain : 
Hastings Sand. { 
Names of Subordinate 
Formations. 
"Tunbridge 
Sand .... 
Wadhurst Clay. 
Ashdown Sand. 
Mineral Composition 
of the Strata. 
Thick¬ 
ness in 
Feet. 
Wells and loam .... 150 
(Blue and brown shale and clay, 
( with a little calc-grit . . . 100 
JHard sand, with some beds of 
( calc-grit . ..160 
A uu 1 , -o j (Mottled white and red clay, 
Ashburnham Beds | sandstone . . . 330 
The picturesque scenery of the ‘‘ High Rocks ” and other 
places in the neighborhood of Tunbridge Wells is caused by 
the steep natural cliffs, to which a hard bed of white sand, 
occurring in the upper part of the Tunbridge Wells Sand, 
mentioned in the above table, gives rise. This bed of “ rock- 
sand ” varies in thickness from 25 to 48 feet. Large masses 
of it, which were by no means hard or capable of making a 
good building-stone, form, nevertheless, projecting rocks with 
perpendicular faces, and resist the degrading action of the riv¬ 
er because, says Mr. Drew, they present a solid mass without 
planes of division. The calcareous sandstone and grit of Til- 
gate Forest, near Cuckfield, in which the remains of the Igua- 
nodon and Hylseosaurus were first found by Dr. Mantell, 
constitute an upper member of the Tunbridge Wells Sand, 
while the “sand-rock” of the Hastings cliffs, about 100 feet 
thick, is one of the lower members of the same. The rep¬ 
tiles, which are very abundant in this division, consist partly 
of saurians, referred by Owen and Mantell to eight genera, 
among which, besides those already enumerated, we find the 
Megalosaurus and Plesiosaurus. The Pterodactyl also, a fly¬ 
ing reptile, is met with in the same strata, and many remains 
of Chelonians of the genera Trionyx and JEmys^ now confined 
to tropical regions. 
The fishes of the Wealden are chiefly referable to the Ga¬ 
noid and Placoid orders. Among them the teeth and scales 
of Lepidotus are most widely difiused (see Fig. 293). These 
