^10 
TILGATE FOREST. 
bonized remains of vegetables are equally abundant. 
It is exceedingly compact, and offers great resist- 
ance to the hammer ; it scintillates with steel, 
effervesces strongly with acids, and varies con- 
siderably in purity : it contains about 25 per cent, 
of carbonate of lime. Lenticular and tabular crystals 
of carbonate of lime frequently occur in the hollows 
of the stone, and in the medullary cavities of the 
bones, fissures of the lignite, &c. This bed is separ- 
ated into irregular layers, of from three to twelve 
inches in thickness, by blue marl or clay 5 and the 
compact masses, when removed by the quarrymen, 
and cleared of the surrounding sand or clay, pre- 
sent the same concretional or lenticular forms as 
those on the shore, at Hastings, that have been 
washed out by the breakers ; the same kind of 
mammillary projections on the surface of the stone, 
are also observable.* The conglomerate is one of 
the most remarkable features of these strata; it 
appears to be composed of the grosser materials 
of the bed, such as pebbles, rolled masses of sand- 
stone, bones, &c., and even the finer parts of it are 
made up of grains of sand, and comminuted bones, 
teeth, &c. ; the whole has evidently been the sedi- 
ment of a current of water, subsequently consolid- 
ated by a subcrystalline, calcareous cement : almost 
all the bones found in it are more or less rolled, the 
• In many of the quarries, near Tilgate Forest, tlic concretional 
formation of the stone is clearly shown ; although, from its being 
incrustecl with sand, it appears like blocks of the friable sandstone; and 
as it maintains the same sedimentary line as the sand in which it is 
imbedded, the layers appear like tabular strata, till examined with 
attention. 
