r. Allan in
his sketch of the geology of that neighbourhood;** in which the perfect
preservation of the shells, and their near approach to those of the
adjoining sea at the present day, are particularly mentioned; and it is
inferred that the date of the deposit which affords them, is anterior to
that of the conglomerate containing the bones of extinct quadrupeds,
likewise found in that country. M. Brongniart also, who examined the
place himself, mentions the recent accumulation which occurs at St.
Hospice, about sixty feet above the present level of the sea, as
containing marine shells in a scarcely fossil state (a peine fossiles)
and he describes the mass in which they occur, as belonging to a
formation still more recent than the upper marine beds of the environs of
Paris.***

(*Footnote. Prevost manuscripts. See hereafter.)

(**Footnote. Transactions of the Royal Society of Edinburgh volume 8 1818
page 427 etc. See also the previous publications of M. Risso Journal des
Mines tome 34 etc.)

(***Footnote. Brongniart in Cuvier Ossemens Fossiles; 2nd Edit. volume 2
page 427.)

The geological period indicated by these facts, being probably more
recent than the tertiary beds containing nummulites, and generally than
the Paris and London strata, accords with the date which has hitherto
been assigned to the crag beds of Suffolk, Essex, and Norfolk:* but later
observations render doubtful the opinion generally received respecting
the age of these remarkable deposits, and a full and satisfactory account
of them is still a desideratum in the geology of England. When, also, our
imperfect acquaintance with the travertino of Italy, and other very
modern limestones containing freshwater shells, is considered,** the
continual deposition of which, at the present time, cannot be questioned
(though probably the greater part of the masses which consist of them may
belong to an era preceding the actual condition of the earth's surface)
it would seem that the whole subject of these newer calcareous formations
requires elucidation: and, if the inferences connected with them do not
throw considerable doubt upon some opinions at present generally
received, they show, at least, that a great deal more is to be learned
respecting the operations and products of the most recent geological
epochs, than is commonly supposed.

(*Footnote. Conybeare and Phillips Outlines etc. page 11, Geological
Transactions 1 page 327 etc. Taylor in Geological