FIRST PERIOD OF THE ANCIENT WORLD. 7 
able abundanee, in various positions, large and strong trunks of plants, which 
appear to remain in their natural position, and which have been able to 
withstand the force of such torrents, if it can be proved that any such ex- 
isted. These vertical plants I have generally found to be Sigillarie. The 
Stigmariz and Calamites, on the contrary, do not appear to have been suffi- 
ciently strong to resist any revolutionary influence. 
Below the high main seam (which, according to Mr Forster’s section 
of the strata, is 150 yards below the surface), in a bed of sandstone, there are 
numbers of fossil plants standing erect, with their roots in a small seam of 
coal lying below. These stems, as will be perceived by the following dia- 
gram, are truncated and lost in the seam, leaving room to believe that they 
may have formed part of that combustible mass or bed. 
a, High main seam. 
4, Sandstone, in which are seen the trunks, d, d. 
c, Small seam of coal, in which the roots of the trunks are imbedded. 
Again, in some of the seams, when the coal is worked away by the 
miners, the roof often falls in. This is, ina considerable degree, owing to the 
number of vegetable impressions breaking the coherence of the stratum, and 
bringing these fossils along with them. It is observed, that, in almost every 
instance, they are surrounded by a coating of very fine coal, about one-half 
or three-fourths of an inch thick, having a polished surface, with very little 
attachment to the surrounding matter. This, I doubt not, is the cause of 
the fall, the fossil dropping out sometimes as much as three feet in length. 
and leaving a hole in the roof almost perfectly circular. Often it falls in 
