460 E. T. DUMBLE PROBLEM OF TEXAS TERTIARY SANDS 



white, and some of the sandy clays show typical badland weathering. 

 The topographic expression is generally flat. 



In the upper beds, referred to this formation by Baker and Suman, 

 some of the sands have a porcelaneous cement, others limonitic, and still 

 others contain streaks and balls of white clay having the appearance of 

 porcelain. 



Lignitic material is abundant, disseminated through the beds in frag- 

 mentary form, as carbonaceous coatings, and in lenticular beds ; but few, 

 if any, deposits of workable lignite are known to occur in the Yegua east 

 of the line of the International & Great N'orthern Eailway. 



Gypsum is very abundant. In the lower portion of the beds, where it 

 predominates, it occurs as large masses of selenite of irregular form. 

 Elsewhere it occurs as crystals of selenite, sometimes of large size, or as 

 fragments intermingled with the sands and clays. In some localities 

 these gyjisum fragments constitute a considerable percentage of the sand 

 bed. Saliferous strata also occur. 



The cannon-ball concretions of the Eio Grande are found here in 

 abundance. While some of these are of spherical shape, as on that stream, 

 many of the clay-ironstone concretions are in the form of flattened masses, 

 some of them 2 to 3 feet in diameter. They are usually altered to 

 limonite, and these limonite concretions and impregnations are character- 

 istic of the beds. Occasionally the limonitic concretions have streaks of 

 calc-spar through them, but true calcareous concretions are ajiparently 

 absent. Silicified wood is plentiful as logs of large size and as fragments 

 scattered through the formation from bottom to top, but none of it is 

 opalized. 



Marine invertebrate fossils occur occasionally as poorly preserved casts 

 in connection with pockets or concretions of greensand marls. Fossil 

 plants are found abundantly at many places. 



The Yegua belt has an average width of .12 miles. Its greatest width, 

 22 miles, is found along the ISTeches Eiver, while on the Sabine it narrows 

 to 3 miles. In dip it varies from 40 feet to tlie mile to more than 100 

 and has a thickness of 400 to 800 feet. 



Fayette. — The fossils on which the correlation of Kennedy's Wellborn 

 beds with the Fayette was based were collected from the lowest beds of 

 the sands. The more recent work of Deussen and Yaughan seems to 

 indicate that this may prove to be Jackson. In this event, we know of 

 uo Faj^ette east of the Brazos, unless it l)c such remnantal areas of sand 

 and clay as those between Blix and Huntington. 



On the west side of Jacks Bayou, just east of Blix, in Angelina County, 

 there is a ridge of evenly bedded medium or fine-grained sandstone of 



