ALLUVIAL DEPOSITS. 
^^2 
Hence it is obvious, that a deposition of carbonate 
of lime from water may be occasioned either 
from an absorption of carbonic acid, or from the 
loss of that portion which exists in excess. 
Of the incrusting springs that occur in Sussex, 
one of the most powerful has its source in the 
beds of limestone of the Wealden formation ; it 
is situated in a wood at Pounceford, between 
Heathfield and Burwash. It forms an inconsider- 
able cascade over a rock of sandstone, and pur- 
suing a tortuous course, deposits carbonate of lime 
on every extraneous body that lies in its channel ; 
converting the mosses and other vegetables within 
reach of its waters, into masses of calcareous tufa. 
The specimens in my possession consist of incrust- 
ations of mosses, Equiseta, small branches of trees, 
leaves, &c. : some of them are composed of a porous 
friable calcareous earth ; and others of a compact 
carbonate of lime of a subcrystalline structure, 
perfectly resembling the tufaceous depositions of 
Derbyshire. When recently collected, the moss 
on the surface was green and flourishing, and had 
evidently continued to vegetate, although the roots, 
&c. were completely imbedded in the stone. 
The water has not been analysed, but is evi- 
dently possessed of very considerable lapidescent 
powers, and might doubtless be applied to the same 
ingenious purposes as the waters of Tivoli, and the 
baths of St. Phillip, in Tuscany.* 
* At the batlis of St. Phillip, in Tuscany, a manufactory is esta- 
blished, where casts of medals and bas-reliefs are formed of calcareous 
tufa. The water is pro{)ellcd from a considerable height into a large 
vessel, and being interrupted in its fall by a wooden cross, is separated 
