THE FOSSIL FLORA. 
163 
right position by the force of gravity, as is known occasionally to be 
the case during floods, where trees are removed along with the soil 
in which they grew ; and this seems to have been certainly the case 
with the upright stems in the sandstone of the French mine of St. 
Etienne, where the different levels of their roots prove, as M. Con¬ 
stant Prevost has already remarked [Diet, des Sc. art. Termin') that 
they could not have grown where they now stand; but in the Lias 
Cliffs near Whitby, where the fragile stems of Equisetum columnare 
occur perpendicularly, they cannot have been so placed by force of 
gravity ; and if evidence the most conclusive be required of the fact 
of vegetables having sometimes been overwhelmed on the spots where 
they grew during the deposition of the strata, it is furnished by the 
Fossil Forest of what is called the “Dirt bed,” immediately over the 
fine building stone of the Island of Portland; and sub-marine forests 
of the present day supply us with the same fact, connected with a 
different order of things. 
The fossils of the Coal measures occur often in groups; thus in 
the roof of the coal in Felling Colliery, the remains of Pecopteris 
heterophylla, (see Vol. 1, plate 38,) were, a few years ago, most 
abundant; they occurred alone, almost unmixed with any other, over 
a considerable space, but, beyond that, have been rarely found, so 
that they are now comparatively scarce. Could such grouping have 
taken place if the individuals had been swept from a distance? 
In plate 31, Vol. 1, we figured a nearly perfect specimen of Stig- 
maria Ficoides, which was found, with two others, almost as perfect, 
in the shale forming the covering of the coal, in the Bensham seam, 
Jarrow Colliery, at the depth of about two hundred fathoms from the 
surface; since that period, fourteen others have occurred, all in the 
same bed, and within a space of about six hundred yards square.* 
Two of the specimens above alluded to, have been recently re¬ 
moved from the mine ; one is the impression of the under side of the 
plant, shewing the central concavity, and fifteen arms proceeding 
from it, four of which are distinctly branched; they are all trunca¬ 
ted, the longest being four feet and a half. 
* That a proper idea may be formed of the abundance in which the remains 
of Stigmaria occur in this bed, it should be stated, that those alluded to above, 
have all been brought to light in a short period, by the working of the mine; 
and that only in the roof of the passages, as from the mode of operation ren¬ 
dered necessary by the nature of the bed above the coal, at the first working, 
two thirds of that substance is left standing for its support; when this coal is 
afterwards removed, the roof will fall, so that it may never be possible to ascer¬ 
tain how many of these fossils now remain covered up. 
M 3 
