162 Mr Bowman on the Fossil Trees found in the Line of 



with those above it, just described, a remarkable coincidence 

 will be perceived ; the band of shale is in both overlaid and 

 underlaid by the same sandstone, composed in both of the same 

 peculiar character, and separated from the sarfflstone by an 

 equally abrupt and definite boundary. In the upper strata, 

 the band is, however, fifteen inches thick, while that in the 

 tree is only ten inches ; a difference to be explained in the 

 sequel. 



This coincidence in the order and quality of the deposits 

 within and around the tree, naturally leads us to inquire if 

 they will not afford some clue to the actual circumstances 

 under which it was interred. Had the tree been originally 

 hollow or even cellular, the same blue or grey shale which is 

 deposited around it, would have forced itself into the interior ; 

 unless, indeed, when entire, there had been no aperture, or 

 if its top had been above the surface of the water. In either 

 case, the great lateral pressure of the surrounding water and 

 sediment would have caused its sides to collapse. Most fossil 

 trees found erect have retained their circular form, and are 

 usually filled with a material which differs from the surround- 

 ing matrix, and corresponds with an upper bed. This is the 

 case with the specimen under examination, and the circum- 

 stance goes far to prove that it was originally solid ; while, on 

 the other hand, the inorganic matter which now represents it 

 affords indisputable evidence that it was, at some period^ a 

 hollow cylinder, which admitted soft sediment through a wide 

 aperture, because these fossil trunks often contain fern leaves 

 and large portions of calamites, &c. with their beautiful mark- 

 ings uninjured. The question therefore arises, how these con- 

 tradictory-appearances can be reconciled, and I think a satis- 

 factory solution maybe found in the process already described, 

 by which the solid wood in tropical climates is removed while 

 the bark remains sound, and which need not be repeated. It 

 is only necessary to notice one or two apparent discrepancies. 

 The sandstone which forms the lower part of the tree is not 

 so thick as the bed above, which I consider as the same de- 

 posit. Had the hollow tree been a cylinder of uniform dia- 

 meter, the thickness of the deposits within and above it would 

 have been the same. But being somewhat conical^ the base 



