A recently discovered buried hill, at least 77 feet high, is composed of strata of the Wilcox group (lower Eocene) and covered on its flanks by cross-bedded sands of the lower Carrizo and at the top by level-bedded shales and silts of the upper Carrizo formation. Peculiar small funnel-shaped pits filled with Carrizo sand extend into the underlying Wilcox ball clay at the peak of the hill. Other extensions fill shrinkage cracks of the clay.

The geographic distribution, lithology, thickness, and paleontology of the subsurface Woodford in the Permian basin are described and illustrated. On the basis of conodonts and spores, the Woodford is assigned to the Upper Devonian and correlated with the Ready Pay member of the Percha shale in New Mexico, Woodford and Chattanooga of Oklahoma, Kansas, and Arkansas, and tentatively correlated with the Upper Devonian parts of the Caballos novaculite and Arkansas novaculite of Texas and Arkansas.

The Barrilla Mountains, in the northeastern part of the Davis Mountains of Trans-Pecos Texas, are composed of Tertiary volcanic materials. Five tuffs and five lava flows, 1500 feet thick occurring throughout the mountains, persist in thickness and lithologic characteristics. Their upper surfaces show little erosion. The lavas are chiefly Silicic and soda rich. The volcanic succession is underlain by a Tertiary sandstone above Upper Cretaceous marine formations.

The Barrilla Mountains, in the northeastern part of the Davis Mountains of Trans-Pecos Texas, are composed of Tertiary volcanic materials. Five tuffs and five lava flows, 1500 feet thick occurring throughout the mountains, persist in thickness and lithologic characteristics. Their upper surfaces show little erosion. The lavas are chiefly silicic and soda rich. The volcanic succession is underlain by a Tertiary sandstone above Upper Cretaceous marine formations.