WHITE ROCK, HASTINGS. 
195 
colour, and laminated structure, from 3 to 5 feet 
thick. 
3. Tilgate stone, bluish grey, with numerous 
casts of bivalves, 2 feet. 
4. White and fawn-coloured sand, 15 feet. 
5. Tilgate stone, w'ith bivalves, 1^ foot. 
6. Thin layers of a coarse friable aggregate, 
with remains of fishes, vegetables, and paludinm, 
2 to G inches. 
7. Laminated ferruginous sandstone, with 
layers of blue clay and shale ; containing innu- 
merable traces of carbonized vegetables, 3 to 4 
feet. 
The Tilgate stone resembles, in every respect, 
the sandstone of the forest from which its name is 
derived ; it abounds in casts of a small species 
of cyclas, which is comparatively rare in the stone 
of the interior of the county. The thickness of 
the masses that are in situ, docs not exceed two 
feet ; but there are detached blocks on the beach 
which are upwards of four feet. The alternations 
of the sand and Tilgate stone, and the concre- 
tionary form of the latter, are strikingly displayed 
at this interesting and picturesque spot.* The 
sandstone occurs, not in continuous layers, but in 
irreo'ular lenticular masses imbedded in the sand, 
yet preserving the same sedimentary line ; as if its 
consolidation were owing to the infiltration of a 
fluid holding carbonate of lime in solution, which 
produced a subcrystalline structure in certain 
portions of the bed, subsequently to their mecha- 
* 
Sec the section in the plate. 
o 2 
