50 GULF TERTIARY OF TEXAS. 



of very frequent occurrence throughout these strata, and in some places the 

 sands are stained black by the presence of oxide of manganese. Silicified wood 

 is also of very frequent occurrence through the series, especially in the clays. 

 Generally it is of the ordinary character of the Tertiary beds, consisting of 

 fragments of trunks of trees, black in the interior and gray or buff color on 

 the outside.* Sometimes, however, the silicified wood of the Fayette Beds 

 is beautifully opalized, showing alternating layers of brown and white opal, 

 with a bright glossy surface and a conchoidal fracture. 



This whole series bears signs of a littoral deposit, and among the most 

 characteristic evidences of this are the signs of slight erosion, followed by 

 subsequent sedimentation. Frequently clays and sands overlie each other 

 unconformable, but this unconformability is of only local extent, and doubt- 

 less due to changes in the currents of the waters under which the strata were 

 deposited. Also, the presence of lumps of clay in the sandy strata tends to show 

 an erosion of the underlying clay beds. The dip of these strata is from 

 to 5 degrees to the southeast. This trend is especially observable in the clays 

 forming the lower part of the series, while the sands of the upper part show 

 a greater tendency towards a horizontal dip. In this respect they resemble 

 the Grand Gulf sands of Louisiana and other Mississippi States. 



Indigenous fossil remains of fauna have nowhere been found as yet in the 

 Fayette Beds of Texas, f In one place, two miles below the mouth of Yegua 

 Creek, on the Brazos River, were found worn fragments of shark teeth, pieces 

 of bone one-half to two inches in diameter, rounded fragments of silicified 

 wood, and lumps of light watery-green clay in the cross-bedded sands of this 

 series. These, however, prove by their worn and rounded character that 

 they have been derived from underlying strata by the erosion of a shore line, 

 and it is more than probable that the organic remains have been carried down 

 into this bed, during its deposition, by the waters tributary to the Gulf as it 

 existed at that time. A similar instance of worn fragments of fossils is to be 

 seen eight miles below Roma, on the Rio Grande, but here also they are prob- 

 ably derived from older beds. There are, however, numerous remains of the 

 flora of this epoch imbedded in the strata of the Fayette Beds. As has 

 already been stated, the clays of the lower part of the series contain many 

 impressions of vegetable remains in the shape of leaves, trunks of trees, etc. 

 At one point on the Colorado, four miles above La Grange, there are found 



*It may be stated here, that in this respect the silicified wood resembles that of the lava 

 beds of Montana, Wyoming, and elsewhere in the Western States and Territories. 



f Exception must be made to this rule if the beds on the Rio Grande containing Ostrea 

 georgiana are included in the Fayette Beds. Exception must also be made of the vertebrate 

 and invertebrate forms mentioned by Dr. Buckley (First Annual Report of the Geological 

 and Agricultural Survey of Texas, pp. 64, 65). 



