1(34 On the. Fossil Trees found at Dixon Fold. 



became hollow about the period when the change in the de- 

 posit from the lower shale to the sandstone about it took 

 place. 



I have now shewn that the trunk of this fossil is a cast in 

 sandstone of the original tree, and that it is composed of the 

 same strata, placed in the same order of succession, and with 

 the same transitions, now abrupt and now gradual, as are found 

 in the rock above it : I have accounted for this general cor- 

 respondence, for several slight inequalities of thickness, and 

 for the difference found in the material within the base of the 

 tree, and in the imbedding matrix. 1 have offered strong evi- 

 dence from the laws of vegetable physiology, that it was a 

 dicotyledonous hard-wooded timber tree, and the testimony of 

 three scientific travellers, two being distinguished botanists, 

 that such trees in our own day, rapidly become hollow by the 

 decay of their wood in hot and humid climates, while the bark 

 remains sound ; and I have given an example from the coal- 

 strata of a fossil stem in which a portion of the original woody 

 structure was preserved among the inorganic matter that filled 

 its interior. I am therefore of opinion, after a careful con- 

 sideration of all the evidence, that the tree in question, in 

 common with numerous others found in similar situations, was 

 a hard-wooded timber tree ; that it grew on the spot where it 

 still stands ; and after the subsidence of the land, remained in 

 an erect position with its top above the water ; that it was 

 converted into a hollow cylinder by the decay of its wood from 

 natural causes still in operation, and, when altogether sub- 

 merged, became a mould for the reception of sediment from 

 the turbid waters, and was gradually covered up by subsequent 

 deposits, preserving the exact form and character of its ori- 

 ginal woody surface, as the carbonized exterior has that of its 

 bark ; and that when at length it is now disinterred, after a 

 lapse of time so vast that man will probably never be able to 

 estimate or to comprehend it, it presents to us an exact cast 

 or model of the trunk of a growing forest tree of the carboni- 

 ferous era. 



In addition to the interesting data already given, the fossil 

 trees at Dixon Fold seem to me to afford some evidence as to 

 the length of time that has been occupied in the growth of a 



