114 LAMARCK, HIS LIFE AND WORK 
tains, since they have been deposited there at very 
different epochs. But they may often be found mixed 
together, because the movements of the water, the 
currents, submarine volcanoes, etc., have overturned 
the beds, yet some regular deposits in water always 
tranquil would be left in quite distant beds : 
Every dry part of the earth’s surface, when the pres- 
ence or the abundance of marine fossils prove that 
formerly the sea has remained in that place, has 
necessarily twice received, for a single incursion of the 
sea, littoral shells, and once deep-sea shells, in three 
different deposits—this will not be disputed. But as 
such an incursion of the sea can only be accomplished 
by a period of immense duration, it follows that the 
littoral shells deposited at the first sojourn of the 
edge of the sea, and constituting the first deposit, 
have been destroyed—that is to say, have not been 
preserved to the present time; while the deep-water 
shells form the second deposit, and there the littoral 
shells of the third deposit are, in fact, the only ones 
which now exist, and which constitute the fossils that 
we see.” 
He again asserts that these deposits could not 
be the result of any sudden catastrophe, because of 
the necessarily long sojourn of the sea to account for 
the extensive beds of fossil shells, the remains of 
“infinitely multiplied generations of shelled animals 
which have lived in this place, and have there succes- 
sively deposited their débris.”. He therefore supposes 
that these remains, “continually heaped up, have 
formed these shell banks, become fossilized after the 
lapse of considerable time, and in which it is often 
possible to distinguish different beds.” He then con- 
tinues his line of anti-catastrophic reasoning, and we 
must remember that in his time facts in biology and 
