84 Geology of Antigua. 
conclusive evidence, that the two classes of rocks were formed . 
under different circumstances. All the chert beds do not, indeed, 
contain shells; but as they are not found in any of the strata of 
the other formation, they seem to indicate a palpable line of dis- 
tinction between the two. 
If then we refer the chert and the petrifactions connected with 
it to a silicious solution, we may still inquire from what source 
‘such a solution could have been derived. It is well known, that 
pure silicious deposits from hot springs are not uncommon, an 
that such springs abound in volcanic countries. . The Geysers of 
Iceland are striking.examples of this kind. And though Antigua 
is not at present a volcanic island, it presents the most manifest 
exhibitions of igneous agency at no very remote period. “These 
silicious deposits and immense fossil transformations may have 
taken place at that time, either from subaqueous springs charged 
with silex, or large bodies of water thrown up from the bowels of 
the earth, and spread otit on the surface in the form of basins. 
The low position of the part of the island where these beds 
abound, would perhaps favor this supposition. I am, indeed, ~ 
aware that the subject of silicious solutions is yet involved in 
great mystery—the process by which nature dissolves_silica 
having yet ina great measure evaded the scrutinizing eye of sci- 
ence—but the fact is among the best ascertained phenomena of 
- geology, and may therefore be.employed in the explanation of 
those deposits, which other circumstances would sptepMy refer 
to such an origin. - 
I cannot. but regard the fact, that minute fibres of the roots of 
trees, and tender leaves and fruits, which must certainly have 
been destroyed by the least degree of violence, are found among 
the fossils, as furnishing additional evidence, that the lapidifying 
process took place in a silicious solution. It does not appear pos- 
sible, that any great degree of heat should have existed in the su- 
perficial strata of the earth, without having destroyed every thing 
_ on the surface in the form of woody fibre. 
But there is another class of silicious fossils, found in the eal- 
careous formation, at a distance of several miles from the chert 
ts, which cannot be explained upon any of the preceding 
eS They are the silicified shells and corallines, which 
me 
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