122 Bituminization of Wood. 



was not that of our low swamps. The only logs satisfactorily 

 recognized by me in this bed, were those of the water oak (Q.aer- 

 cus aquatica) and of a pine, together with a great deal of pine 

 bark, and the strobiles of the Finns teeda ; thickness four feet. 



No. 9. A bed of fine aluminous clay, similar to No. 5 and 7, 

 but of a color deeper than either, and having a greater tendency 

 to form the same kind of nodular concretions, which tend in this 

 bed to arrange themselves in a horizontal and linear mamier ; 

 thickness twelve feet. 



No. 10. A bed of vegetable matter consisting of sticks, leaves, 

 fruit, &c., arranged in thin horizontal laminee, with very thin 

 layers of clay interposed between them. There are a great many 

 logs lying horizontally. The fruit of this swamp hickory ( Juglans 

 aquatica) is very abundant ; the nuts are found compressed, but 

 rarely changed into coal. The burr-like pericarp of the sweet 

 gum, (Liquidambar styraciflua, ) are also found, and occasionally 

 walnuts, (the fruit of the Juglans nigra,) are met with. The logs 

 found in this bed, are those of the cypress, (Cupressus thyoides,) 

 swamp hickory, a cotton-wood, (either the Populus angulata or 

 heterophylla,) and other trees peculiar to the low swamps of 

 Louisiana. A great number of stumps are seen standing erect, 

 and sending their roots deep into, the clay beneath. These are 

 principally cypress of the large size, common in our swamps, the 

 wood of the internal parts retaining much of its hardness and 

 strength, the outside only being softened or changed into coal. 

 These stumps are surrounded by the peculiar knobs or stump- 

 like excrescences, called cypress knees, found on the roots of 

 the cypress when growing in a submerged soil ; and which 

 standing up from the soil, from one to three feet, or sometimes in 

 deep water, six or eight feet, give the area surrounding one of 

 these trees, the same appearance as would be presented if a great 

 many small trees had been cut, and their stumps left standing. 

 They differ however, from stumps, by having rounded tops, cov- 

 ered by a smooth bark. The forest of which this bed contains 

 the remains, was evidently composed of the same trees, which are 

 now the common growth on the new made lands of the delta of 

 the Mississippi. The cypress is peculiar to swamps which are 

 subject to overflow, and the cotton-wood and swamp-hickory are 

 among the first tenants of the land, after it has risen, by succes- 

 sive annual deposition, from the overflowing waters of the Missis- 

 sippi, a little above the level of low water ; thickness three feet. 



