Bituminization of Wood. 121 



of iron, which perhaps gives the blue color to the clay ; thickness 

 20 feet. 



No. 6. A thin, but continuous layer of indurated ferruginous 

 clay of a nature similar to the nodules, presenting, when perfectly 

 indurated, and particularly when weathered, a texture exactly 

 similar to the red shales of the Alleganies, but without any sign 

 of cleavage ; thickness from one to two inches. 



No. 7. A bed of clay, similar to No. 5, but of a somewhat 

 deeper color, and having a similar tendency to produce the uni- 

 form concretions spoken of above ; thickness ten feet. 



No. 8. A bed of vegetable matter, containing logs, branches, 

 &c., lying horizontally, and often so much flattened as to have a 

 diameter six or eight times as great in one direction as in another. 

 They are in various degrees bituminized, and softened ; some be- 

 ing transformed into beautiful coal at one extremity, all appear- 

 ance of woody fibre being obliterated, and consisting of wood at 

 the other so soft that it is easy to crush a stick as large as the arm 

 between the fingers. The logs thus softened, are often cov- 

 ered with thia bark, and look as fresh as if just fallen. The 

 largest logs, when reduced to this state, can be cut through with 

 the spade without difficulty ; and wherever they projected a very 

 short distance from the bank they break off square, presenting 

 the same appearance as if they had been sawed off. In no case 

 did I perceive the least sign of transformation into coal, when this 

 softening had not taken place. On the surface of this bed, which 

 was exposed by the removal of the earth which had fallen on it 

 from the bluff, I discovered, as has already been said, pieces of 

 wood, which were changed into perfect coal, bearing the marks 

 of the axe. These have no doubt been brought there recently, 

 deposited on the denuded surface of the bed, covered by earth 

 from the bluff, and rapidly bituminized. They cannot of course 

 establish the age of the formation, and can only show how short 

 a period these changes sometimes require. Many stumps are 

 seen in this bed, standing erect, and sending their roots to consider- 

 able depth, in the beds below. The outer layers of these stumps 

 scale off when exposed to the atmosphere, the squamas being bitu- 

 minized, the internal parts retaining to some extent the properties 

 of wood. I could not satisfy myself as to the species of tree 

 to which these stumps belonged, but as no cypress stumps are 

 to be seen, it is very reasonable to conclude, that the growth 



Vol. XXXVI, No. 1.— Jan.-April, 1839. 16 



