56 GULF TERTIARY OF TEXAS. 



Central Railway crosses the Brazos, in the southern part of Washington 

 County, are seen similar strata. The sands are highly calcareous as else- 

 where, and as on the Colorado frequently show a very characteristic light 

 watery-green color when wet. Going west from the Brazos River over the 

 " Fayette Beds" to Chappell Hill and Brenham, we travel a rolling prairie, 

 studded with groves of elm, hackberry, and other timber, and covered with 

 a rich black or dark red clay or loamy soil. The town of Chappell Hill is 

 situated on a high point in this formation, and commands a beautiful view of 

 the surrounding country. Frequent outcrops of the Fayette Beds are seen 

 in the Houston and Texas Central Railway cuts both east and west of Bren- 

 ham, and along the G-ulf, Colorado and Santa Fe Railway to the north of the 

 town. These all show the characteristic sands, soft or hardened, with or 

 without calcareous nodules, and white or yellow calcareous clays and marls. 



Friable Fayette sandstone is found in beds at Sealy at from thirty to sev- 

 enty-five feet below the surface. It is overlaid by stiff massive clay, with many 

 root impressions even at a depth of over twenty- five feet, which belongs to 

 the Post-Tertiary strata, and will be treated farther on. 



The coarse sands passed through at considerable depths in boring artesian 

 wells at Houston and Galveston are probably of the same formation as those 

 already described.* At these places, however, as at Sealy and elsewhere 

 near the coast, the sands are overlaid by clay deposits, like those mentioned 

 above. Whether these overlie the Fayette Beds unconformably, there is as 

 yet not sufficient evidence to state definitely, but they are so different in con- 

 sistency, composition, and general character that they are here treated under 

 a separate heading. (See Coast Clays.) 



EIO GKANDE SECTION. 



The strata on the Rio Grande that represent the Fayette Beds are very 

 similar in every respect to those in the region of the Brazos and Colorado. 

 In consistency, however, they are somewhat different, but the difference is 

 no greater than is to be expected from the different climatic conditions, and 

 from a possibly greater content of cementing material in the shape of car- 

 bonate of lime and clay in the waters of the Rio Grande than in those of the 

 Brazos or Colorado. The variation consists of an occasionally greater state 

 of induration of the strata. The first undoubted beds of this series are seen 

 five miles below the Texas town of Roma,f and in the Mexican State of Ta- 

 maulipas. They occur in a ledge three hundred yards long and one to six 

 feet high, and consist of hard light sea-green clays with many leaf impressions 



*Unfortunately, reliable records of the strata in these wells are not obtainable. 

 fit is possible, and even probable, that certain beds above and around Roma also belong 

 to this series. (See p. 50.) 



