214 Mr. Wood's Account of some Fossil Stems of Trees. 



tables, which have been rooted in, and grown in the sedimentary deposit 

 of which the bed, No. 2. is the representative. If we suppose this, we 

 account for the innumerable impressions of the various plants covering 

 the face of that bed. The Coal would then be the substratum on which 

 the layer of mud or soil rested, in the middle of which these roots are 

 found, and from which these plants probably vegetated. Supposing this 

 to have been the case, and these plants to have been in their natural 

 state of vegetation, we can only account for the quiet manner in which 

 they have been filled up, and imbedded in the sandstone, by supposing 

 that, by some cause or other, they must have been immersed in water, 

 which has subsequently been the medium of the deposition of the ma- 

 terials forming the bed of sandstone, and which, at the same time, filled 

 the interior of the stem of the plants. The bend in the top of the stem 

 has, we may suppose, been caused by its reaching above the surface of 

 this deposit, and thus, being unsupported, has fallen down and become 

 covered by a deposit of a different nature. 



Without indulging in any theory as to the origin of the Coal itself, 

 if the foregoing premises be made out, we come to the conclusion that 

 the Coal in this particular district was at one time covered by a layer 

 of matter, in which plants of a nature similar to those existing only in 

 tropical climes vegetated ; thus proving an epoch when this was the 

 surface of the earth, and which must have remained so a length of time 

 necessary for the vegetation of these plants, previous to their being en- 

 veloped by the sediment forming the beds in which they are found. 



It may not, perhaps, be irrelevant to state, that, throughout the whole 

 of this district, a bed of black Bituminous Shale, of several feet in thick- 

 ness, occurs a few feet above the " main Post," which, in many places, 

 contains layers of bivalve shells, resembling the fresh-water muscle, 

 shewn in a specimen presented. This bed occurs about 8 or 10 feet 

 above the strata at the top of these fossils. 



I shall afterwards, when the convenience of the Society's Rooms will 

 admit of their reception, have the honour of presenting specimens of all 

 the different strata, from the surface to the seam of Coal above which 

 these fossil remains are found. 



