XXXVi REPORT OF THE STATE GEOLOGIST. 



TIMBER BELT BEDS. 



Proceeding toward the interior, we pass from the Fayette Beds to 

 another series of strata which are tentatively called the Timber Belt 

 Beds. The country underlaid by these beds is rolling and broken, 

 and, in the east, heavily timbered. It rises above the Gulf from 200 

 to 600 feet, and some of the hill tops reach nearly 100 feet higher. 

 All the hills of this district are, however, due simply to the erosive 

 action of atmospheric influences, as nowhere is there evidence of any 

 disturbance since the deposition of the beds, beyond that gradual con- 

 tinental rising which has lifted them so high above the sea whose bot- 

 tom they once occupied. These high hills are capped by a stratum of 

 iron ore or sandstone, the extreme hardness of which has resisted the 

 erosive influence of the atmosphere, and thus preserved its underlying 

 clays from being carried away. The outcrop of these beds occupies a 

 belt of country 125 miles wide at its northeastern border, but narrow- 

 ing to 40 miles north of the Colorado. They are composed of siliceous 

 sand and greensand marls, together with white, brown, or black clays 

 in smaller quantities. Lignite beds are of frequent occurrence, and 

 vary from a few inches to twelve or fourteen feet in thickness. Pe- 

 troleum, asphalt, and natural gas have also been found at places in 

 considerable quantities. 



The sands are usually much cross-bedded, and vary in color from 

 gray to buff. In them are found small black specks of glauconite or 

 greensand (which seems a common and persistent characteristic of 

 these beds), and all degrees of combination may be observed, from a 

 nearly pure siliceous sand, with only traces of glauconite, to a green- 

 sand marl. These marls occur in considerable quantities in the iron 

 districts of Eastern Texas. Thin seams or beds of limestone are also 

 found, and calcareous concretions or nodules, similar to those of the 

 Coast Clays, are abundant throughout this whole series of beds. Some- 

 times the carbonate of lime, instead of being thus segregated, is dis- 

 seminated throughout the sand beds, cementing them into a loose fri- 

 able rock. 



Masses of sandstone formed in this manner, and varying from a few 

 inches to ten feet in diameter, are a highly characteristic feature. They 

 are usually lenticular, although they are also found in other shapes, and 

 while sometimes soft and friable, are often firm and hard. At times 

 they weather in concentric layers, while at others the horizontal strati- 



