T37, 38] SILICIFIED WOOD. 21 



however, I have observed with frequency chiefly in the southern division, 

 both in the Orange Sand and the underlying lignitic strata. 



36. It has heen stated before, that silicified wood occurs with greatest frequency 

 near the planes of contact between the two formations, and is, therefore, most 

 readily accessible in those districts, where the Lignitic formations form the base, 

 and the Orange Sand the upper portion of the hills. I may add, that its 

 frequency of occurrence in the Orange Sand is also dependent upon that of 

 similar organic remains in the underlying lignitic strata. It is, therefore, most 

 abundant where beds of lignite, and clays filled with lignitized trunks and leaves, 

 are most common near the surface — t. e. in W. Tippah, E. Marshall, Lafayette, 

 Calhoun, E. Yallobusha, Choctaw, Ocktibbeha, Winston and Neshoba counties. 

 Whether or not the same is the case in Holmes and Yazoo counties, where lignite 

 beds prevail, I have not learned ; to the southward of these, however, in Hinds, 

 and Claiborne, southward of the lignite beds on the Big Black, silicified wood is 

 very common. It is found more or less, however, in most districts where the 

 Orange Sand prevails in force, and down even to the Sea Coast (Prof. Wailes 

 collected specimens in Hancock county, and another, picked up on the beach at 

 West Pascagoula, has been presented by Mrs. McRae). It is very uncommon, 

 however, on the territory occupied by the cretaceous formation ; except near the 

 western border, and on the territory of the Lower Cretaceous or Eutaxu Group — the 

 latter being also, a lignitic formation, though containing vegetable remains with far 

 less frequency than does the lignitic tertiary. The only specimen found in 

 Tishomingo county, where the Orange Sand is otherwise well developed, was 

 picked up by myself, near Mr. Peden'sMill, on heads of Mackay's Creek, S. 9, T 

 5, R. 10, E., where outcrops of the lignitic cretaceous are abundant. Near Fulton, 

 Itawamba county, silicified wood is also found. These, however, are the only 

 localities in which I have met with this fossil E. of the Tombigbee, notwith- 

 standing that, in Itawamba and Monroe counties, the Orange Sand formation is 



very largely developed, and one would look for its characteristic fossils there 

 if anywhere. 



37. It is true that although silicified wood occurs most frequently near to 

 the surface of the lignitic formations, it is, nevertheless, sometimes found at a 

 considerable elevation above the latter, on the Orange Sand ridges. If we seek 

 for a reconciliation of this fact with the supposition of its derivation from the 

 lignitic strata, we must ask the same question with reference to the cretaceous 

 fossils mentioned above, which were found on hilltops, more than a hundred 

 feet above any cretaceous strata at present existing ; and that too at a con- 

 siderable distance from the region of occurrence of corresponding strata, now 

 found to be composed of hard limestones and heavy clay marls. The same 

 agency which was capable of performing this task of elevation and transporta- 

 tion, would have found little difficulty in doing likewise with semi-lignitized 

 wood, of a much less specific gravity. 



38. But we have more tangible proofs of the disposition of the Orange Sand 

 to appropriate to itself the characteristics of other formations, in the insensible 

 transitions which we frequently find between the materials of the Orange Sand 



