334 
THE GEOLOGY OF MAIDSTONE. 
By W. H. Bensted, Esq. 
{^Continued from page 301.) 
The Kentish Eagstone is a source of very considerable trade to 
Maidstone, and gives employment to many ^vorkraen. Several barges 
are constantly engaged in conveying to the coasts of Kent and Sussex, 
in the marshes of which it is very extensively employed for the banks 
or sea-walls. In Eomney Marsh and on the eastern side of the Isle 
of Sheppey a large expenditure is yearly incurred in thus protecting 
large and valuable tracts of land from the ravages of the sea. The racj- 
stone is also extensively used as a road-stone and for buildings, large 
quantities of the stone being sent to London and other places espe- 
cially for the former purpose. A small quantity is burnt into lime of 
a very superior quality ; but the abundance of chalk in this neighbour- 
hood, and the greater cheapness of that rock, prevents the general use 
of the stronger but more costly stone-lime. 
Many handsome buildings in Maidstone and other places in the 
county are built of it. Of these in Maidstone may be mentioned 
the new gaol, the lunatic asylum, and the new church. Of ancient 
buildings constructed of it are the old parish church of All Saints, 
the Episcopal Palace and College. Many of the London churches, and 
nearly all of those on the banks of the Thames and Medway, have a 
great proportion of this stone in their walls ; and proofs of its dura- 
bility and early application to building purposes may be seen in the 
present condition of Allington and Rochester castles, and most of 
the bridges from Avlesford to Tunbridge. 
In removing the pier of the centre arch at Ajdesford, the mortar, 
made of ragstone-lime, had become so hard that blasting by gun- 
powder was necessary to separate the stones. 
In the Iguanodon quarry alone from twenty-five to thirty men are 
constantly at work. Upon uncovering the stone, the surface and 
sides are found to be water-worn in an extraordinary manner; the 
cause of which will be considered when the superficial clay is de- 
scribed. The upper layer is ver}^ irregular in thickness, and is of an 
^ inferior quality, being porous and cherty, of a 
spongeous structure, and coloured by oxide of 
iron. The principal fossil is Trigonia spinosa^ 
7^^^ which occurs in chalcedony. These trigonise are 
frequently met dispersed over the surface-soil, 
being the relics of beds of stone which have been 
^ subjected to destruction. This layer is about 6 
to 8 inches thick, and of a concretionary cha- 
Fig. 7.— Alcyonium (?) racter. A group of three layers of stone follow 
from upper beds. next; the stone being hard, crystalline, and 
slightly tinged of a ferruginous colour. The upper layer contains 
quantities of the stems and lobes of a singular sponge or zoophyte, in 
