458 E. T. DUMBLE PROBLEM OP TEXAS TERTIARY SANDS 



numerous rolled Cretaceous fossils. Ofteu they form thin-bedded, jointed, 

 irou-stained calcareous sandstones. 



"Toward the east their character gradually but materially changes. They 

 become more ferruginous, and their cemented condition is less marked. The 

 sand occurs more often in a loose condition. Small black land prairies occur. 

 The amount of gravel constantly Increases. 



"The calcareous clays which overlie these on the Brazos undergo similar 

 changes. They become more sandy, gradually lose their lime in balls and 

 pockets, until at Colmesneil they retain only thin, platelike concretions. The 

 ferruginous matter in the form of plates and concretions increases and the 

 beds assume a red color, interspersed with black land prairies. Heavy sands 

 are interbedded with the clays. 



"The most marked difference between the Oakville beds of this region and 

 those of the Colorado seem to be the entire absence of the coarse-grained, 

 cross-bedded sandstones, such as occur at La Grange BlufC. The Grimes 

 County sandstones, in general, are finer of grain, harder, more calcareous, 

 contain fewer Cretaceous fossils, are nearly always thin-bedded and flaggy, 

 and seem to occupy a place of lesser importance as a whole than those of the 

 Colorado." 



The strong unconformity between his Oakville and Payette (?) is 

 brought out in connection with the contacts observed on Eocky Creek 

 north of Anderson. 



"The Eocene member consists of 30 feet of massive, grayish yellow, coarse- 

 grained sandstone, quartzitic throughout, but the silicification has not pro- 

 ceeded to the extent of rendering the entire stratum blue and vitreous. Opal- 

 ized wood is present. 



"Upon the eroded flanks of this Eocene hill lie the Oakville beds. They are 

 here represented by a coarse, brown calcareous sand, stratified and semi- 

 indurated in places, containing numerous fragments derived from the under- 

 lying Eocene quartzite, together with flint and jasper pebbles. At the line of 

 contact the sand is much mixed with clay and lignitized wood. 



"Throughout this region there are occasional Eocene outliers, at times sev- 

 eral miles from the main contact." 



He also notes that the dips of the older sandstones are considerably 

 greater than that of the Oakville. 



Kennedy, Garrett, and Dunible made several trips across these sands 

 between the Colorado and Nueces rivers for the express purpose of ascer- 

 taining whether or not beds intermediate in age between the Frio and 

 Oakville could be found. In every case where the contact was found the 

 Oakville rested either on the Frio or the Fayette, and no indications of 

 other beds were observed. Many localities were found where marine in- 

 vertebrate fossils were abundant and well preserved, but they were nearly 

 all in Yegua territory. The principal, if not only, find in the Fayette 

 was a reef of Ostrea aldbamiensis var. contracta Con. This locality was 



