450 E. T. DlMl'-LK PROBLEM OF TEXAS TERTIARY SANDS 



City. He describes the rock as coarse-grained or conglomerate, with 

 wliite siliceous clay as a cementing material. He notes the lack of fossils 

 and states that it has been referred to tlie Graiid Gulf, of probably 

 Miocene age, for stratigraphic reasons. 



Outside of tbe Sabine, Trinity Kivcr, and Burton outcrops, all of the 

 localities mentioned by Loughridge are occupied by exposures of the Oak- 

 ville or Lapara sands of the present classification. 



Penrose," who studied these sands by boat trips down the Colorado, 

 Brazos, and Eio Grande, used the name Fayette to designate the entire 

 series of deposits lying "between the uppermost fossiliferous strata of the 

 marine Tertiary and the post-Tertiary." In this he followed the example 

 of Hilgard, and he, furthermore, correlated his Fayette with the Grand 

 Gulf of that author. The Fayette of Penrose did not include the Orange 

 sand or Eeynosa (Lafayette). 



On the Colorado, which was first tra\ersed by Penrose and made the 

 basis and type of this division, his Fayette begins near the county line 

 betM^een Bastro]) and Fayette counties, where the last fossiliferous beds 

 were found in White Marl Blufi^. Its base consists of dark clays with 

 lignites, as seen on Barton Creek, followed by light-colored, sulphur-coated 

 clays and sands, forming bluffs on the river and becoming more clayey 

 toward the top, and his description closes Avith the Iduf! of somewhat 

 similar materials south of La Grange. 



On the Brazos, similarly, the Fayette beds, as described by Penrose, 

 begin below Mosely Ferry, where the last Eocene fossils were found, and 

 have at the base gray sands and chocolate clays with lignite beds, followed 

 by light-colored sands and clays to the Houston and Texas Central cross- 

 ing near Hempstead. 



Carrying out the same basis of division, the description of the Fayette, 

 of the Rio Grande begins with the clays overlying the last fossil-bearing 

 beds of the Eocene near Eoma, and includes the sands at the base of the 

 section near Eeynosa. Doctor Penrose, however, recognized the close re- 

 semblance of the light-colored clays and sands, with Ostrea alahamiensis 

 var. confracfa (0. georgiana ? of Penrose report), occurring north of 

 Eoma, to those of the Fayette section. ^^ 



A year or two later it was found that the body of dark-colored clays 

 with lignite, which formed the base of the Fayette division of Penrose, 

 carried a marine invertebrate fauna in tlieir exposures in branches of the 

 Yegua. As these fossils pro\ed to be of Lower Claiborne age, these clays 



10 First Ann. Kept. Geol. Siirv. Texas, p. 47 et seq. 



li First Ann. Rept. Geol. Surv. Texas, p. .56. These are included in tbe Fayette beds 

 of our present classification. Geol. S. W. Texas. Trans. A. I. M. E., vol. 33. p. 969. 



