84 On the PhospJioric Strata of the Chalk Formation. 
In the Isle of Wight, between Black-Gang Chine and A.ther- 
fielcl, many of the masses of fossiliferous rocks are more than 
ordinarily phosphoric, but, as they frequently contain a large 
proportion of the carbonates of iron and lime, they do not afford 
a high percentage. There are, however, some exceptions, amongst 
which may be particularized the blocks of fossils in the scaphite, 
the lower crioceres, and the second gryphaea beds ; besides the 
casts of ammonites and scaphltes which lie upon the beach. The 
specimens which have been examined show them to be very rich 
in phosphatic matter. 
There is ample room in this locality for a diligent search 
after phosphate of lime, with a good prospect of obtaining large 
quantities. Such an investigation would be greatly facilitated 
by consulting Dr. Fitton's ' Stratigraphical Account of the Section 
from Atherfield to Rocken End,' published in the third volume 
of the Quarterly Journal of the Geological Society of London. 
The constant occurrence of the beds of phosphoric marl and 
fossils in the upper green-sand above the gault, and of the fossils 
in the lower green-sand below the gault, at places very remotely 
distant from each other, seems to indicate a general fact, that at 
certain geological epochs a vast deposition or outpouring of 
phosphoric acid took place ; and consequently, it is fair to pre- 
sume that the strata above described, which are the records or 
present representatives of those epochs, would everywhere afford 
these phosphatic remains. 
In the foregoing pages an attempt has been made to describe 
\he present condition of certain deposits of phosphate of lime, and, 
in so doing, speculation as to the origin of this substance has 
been kept in the background — it being the wish of the writers 
to render their account as simple and useful as possible. Whence 
and in what manner the phosphoric acid found its way into fossils, 
which are usually composed of carbonate of lime or of silica, are 
certainly questions of very considerable interest both to the 
geologist and chemist, but can hardly be said to affect the agri- 
cultural reader. That the phosphate of lime has penetrated 
the various fossils and nodules^rom without, there scarcely exists 
the smallest question ; and were it possible that it had been 
primarily derived from some true mineral deposit (like that of 
Estreniadura), the circumstance might stimulate to increased 
search after so invaluable a treasure. But there is every reason 
to believe that this vast quantity of a substance which is by no 
means superabundant on the surface of our planet is to be 
ascribed to the presence, at some epoch of its existence, of a 
very great amount of animal life which served as the means of its 
concentration. 
