XVIII . — On the Geognostic al Situation of the Reygate Stone , and of the 
Fuller s Earth at Nut field. 
By THOMAS WEBSTER, Esq. 
SECRETARY OF THE GEOLOGICAL SOCIETY. 
[Read May 1, 1819.] 
Every observation that tends to determine more accurately the 
geognostical place of any bed must be of some value, but more 
particularly if it be used for an economical purpose. 
On this account I gladly availed myself of a late opportunity of 
examining in situ the well known Reygate stone, which is so exten- 
sively employed in London and its neighbourhood. 
I believe the first author who described the situation of this bed 
was Mr. Farey, who, in the list of the English strata which he gives 
in his Survey of Derbyshire, states, that the lower chalk, or that 
without flints, gradually becomes harder and more sandy towards 
the bottom ; and that in this bed the Reygate firestone is situated, 
an opinion which I believe is still entertained by some. 
In a memoir which I had the honour to present to this Society, 
and which is published in the 2d volume of its Transactions, as also 
in the table which I formed of the upper beds of England from 
the observations made in the Isle of Wight and other places,' I 
ventured to consider the Reygate stone as identical with the green 
sandstone ; but as in this I was guided by a series of strong analogies 
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