1895.] NATURAL SCIENCES OF PHILADELPHIA. HI 



12. Alternate strata of brown sand and laminated iron 



ore, one generally wavy and not more than two 

 to six inches with sand from one to two feet 

 thick 20 feet 



13. Pale-blue and brown clay mottled in places and 



laminated in others 15 feet 



14. Alternate strata of glauconitic brown sand and 



iron ore, the ore generally irregularly de- 

 posited, laminated and silicious and not exceed- 

 ing six inches to one one foot, the sand from six 

 inches to two feet thick 55 feet 



15. Brown sand forming surface at Bullard, altered 



green sand changing to yellow a few feet under 

 ground 40 feet 



16. Dark green sand containing a few fossil shells and 



fish teeth 24 feet 



^.o 17. Lignite or "black dirt" containing leaves ... 2 feet 

 h3 "3 18. Dark lignitic clay * . . . 5 feet 



Nos. 17 and 18 of this section belong to the lignitic beds. 



On approaching the Brazos the base of these beds is again seen 

 about two miles south of Calvert, in Robertson County, where they 

 form a ridge of brownish- yellow sandstone of very similar texture 

 and appearance as the sandstones in Harrison County, and appear to 

 be altogether unfossiliferous. Where the International and Great 

 Northern Railway crosses the Brazos River these beds are again seen 

 in the following section : 



1. Yellow sandy clay with limy concretions .... 20 feet 



2. Brown sand and sandstones interstratified ... 4 to 6 feet 



3. Dark green, almost black, unfossiliferous sand . 5 feet 



4. Thinly laminated dark green sand 6 feet 



5. Irregular belt of ferruginous sandstone i to 1 foot 



6. Dark green, almost black, sand, to water .... 3 feet 

 The lower and upper divisions grade into each other so imper- 

 ceptibly that so far as the actual division is lithologically concerned 

 any line of separation would be but a very arbitrary one. The 

 wide distinction, however, in the state of preservation and condition 

 of the contained fossils might possibly enable us to approximately 

 indicate the limits within which the several beds might be assigned 

 to each. As already stated the fossils of the lower or Mount Sel- 



