FOSSIL PLANTS. 343 
been formed in water of a certain depth, the matter always bears 
evident traces of its origin from land vegetation, and never from 
marine plants. The lower part of a bed of coal, worked near 
the mouth of Yellow creek, Ohio, is a kind of cannel coal, or very 
bituminous compact shale, full of the remains of fishes, whose en- 
tire skeletons vary in length from one inch to one foot. Yet this 
shale has an abundance of the remains of land plants mixed in its 
compound. The same case is observable in Kentucky — for exam- 
ple, at Airdrie, on Green river, where the upper coal (No. 11 of 
the Kentucky section) is overlaid by a bituminous laminated 
shale, containing teeth of large fishes with trunks of Sigillaria, 
Lepidodendron, etc., and branches and leaves of ferns. Those 
who have examined our immersed peat bogs along the shores of 
New Jersey, have seen in activity a formation of the same kind, 
where logs of large trees are fished from a depth of ten or fifteen 
feet, out of beds of peat submerged in water deep enough to feed 
a variety of fishes; while here and there, small islands, half float- 
ing fragments of wood or heaps of mud, are covered with a luxu- 
riant growth of ferns, reeds, or bushes, which throw their debris 
to the surface, to be conveyed to the bottom and there mixed in 
the bed of mud, an incipient shale, with animal remains. 
Among the various metamorphoses to which remains of plants 
have been subjected in the shale by compression, decomposition 
and other chemical and mechanical agencies, one peculiar phenom- 
enon is worth noticing here. In the shale covering the bed of 
anthracite of Rhode Island, the whole carbonaceous matter of the 
plants has been destroyed by heat, and the mere skeleton of 
the leaves and other remains is marked upon the shale as a more 
or less distinct mould, often covered by a whitish incrustation of 
selenite. In this process of fusion, the vegetable fragments have 
been distorted in such a way that they often present an appear- 
ance far different from that of the species to which they belong. 
For example, in some branches of ferns, the leaflets have been, on 
one side of the pinne, extended to double their original length, 
and narrowed in proportion, while on the other side they have been 
relatively contracted and widened. Wi thout an examination of 
the shale at Newport, it would be difficult to account for such a 
metamorphosis. At this locality, the shales present along the 
shore a series of low undulations, resembling slightly elevated 
wayes; and there one can see that, in the state of fusion of the 
