NOVA SCOTIA COAL-MEASURES. 
411 
of the same cliff is exhibited, in order to show the manner of 
occurrence of erect fossil trees at right angles to the planes 
of the inclined strata. 
In the sandstone which filled their interiors, I frequently 
observed fern-leaves, and sometimes fragments of Stigmaria^ 
which had evidently entered together with sediment after 
the trunk had decayed and become hollow, and while it was 
still standing under water. Thus the tree, a. Fig. 440, rep¬ 
resented in the 
bed e in the sec¬ 
tion, Fig. 439, is 
a hollow trunk 
five feet eight 
inches in length, 
traversing vari- 
ous strata, and 
cut off at the 
top by a layer 
of clay two feet 
thick, on which 
rests a seam of 
coal (^, Fig. 440) 
one foot thick. ^ 
(c and cZ), while at a greater height the trees f and g rest 
upon a thin seam of coal (e), and above them is an underclay, 
supporting the four-foot coal. 
Occasionally the layers of matter in the inside of the tree 
are more numerous than those without; but it is more com¬ 
mon in the coal-measures of all countries to find a cvlinder 
of pure sandstone—the cast of the interior of a tree—inter¬ 
secting a great many alternating beds of shale and sand¬ 
stone, which originally enveloped the trunk as it stood erect 
in the water. Such a want of correspondence in the materi¬ 
als outside and inside, is just what we might expect if we 
reflect on the difference of time at which the deposition of 
sediment will take place in the two cases; the imbedding 
of the tree having gone on for many years before its decay 
had made much progress. In many places distinct proof is 
seen that the enveloping strata took years to accumulate, for 
some of the sandstones surrounding erect sigillarian trunks 
support at different levels roots and stems of Calamites; the 
Catamites having begun to grow after the older Sigillarim 
had been partially buried. 
The general absence of structure in the interior of the 
large fossil trees of the Coal implies the very durable nature 
of their bark, as compared with their woody portion. The 
Fig. 440. 
On this coal again stood two large trees 
