199 LiGNiTic Stage 7 



is no proof that such beds exist ; on the contrary, if the expan- 

 sion of the Lower Claiborne in this part of the State is, as it 

 would seem to be from the meagre data we have, it is quite 

 probable that it overlaps the Lignitic and Midway stages and 

 meets the Cretaceous. 



Colorado River. — On this river the Lignitic beds must be 

 very poorly represented, for Penrose writes that five miles by 

 river below the outcrops of the Basal clays in the neighborhood 

 of Webberville, a low fossiliferous bluff is seen. These fossils 

 identified by the present writer, are of Lower Claiborne horizon. 

 Hence the Lignitic deposits can have on this river a width of 

 no more than five miles. 



Brazos River. — It is on the Brazos River where the Lignitic 

 stage is typically exhibited. Penrose thus describes this 

 sedlion : * 



' ' About a mile and a half below Pond creek is seen an out- 

 crop of Tertiary sand, containing black specks and rendered 

 plastic by a white clay. It is capped by serai -indurated 

 Quaternary gravel and sand, and contains large nodules 

 which give a strong reaction for carbonate of lime, and which 

 are simply hardened masses of the enveloping sand. They are 

 one to eight feet in diameter, hard, kidney-shaped, flat or 

 nodular, and project out of the compact sand}' bluff in a most 

 characteristic manner. Loose fragments of silicified wood, 

 which have also doubtless been derived from the same bed, 

 lie among the many nodules that have been eroded out. So 

 many of these rocky masses have been loosened from the sand 

 and piled up in the bed of the river that they have obstructed 

 its course, and have formed rapids. Many of these rocks are 

 round or oval, and are locally known as " kettle bottoms." 

 Such strata as these are seen down the river for a mile and a 

 half from this point, where they dip under a series of gray clays 

 containing beds of lignite, varying from one to five feet thick 

 and associated with ferruginous sand. The clay contains large 

 masses of silicified wood, which is sometimes seen in places in the 

 bed, but more often has been weathered out and lies in the bed 

 of the stream. .Occasionally nodules of clay ironstone, gen- 

 erally in a semi-oxidized condition, are found. Such strata are 

 exposed for about a mile, when the gray sands vinth calcareous 



ist Ann'l. Rept. Geol. Sur. Tex., 1890, p. 26. 



