RICHLAND SANDSTONE. 205 



Rochelle northeastward to the Colorado, along Deep Creek, and just east of 

 the town of Milburn. 



At its southwestern end it is coarsely conglomeritic, and contains pebbles 

 often weighing a pound or two. These pebbles are almost entirely well 

 rounded flint of various colors, derived directly from the Silurian, and ce- 

 mented in some places by iron and in others by silica. Near Rochelle, the 

 conglomerate attains a maximum thickness of fifty feet, and because of its 

 development at Rochelle I propose the name of Rochelle Conglomerate bed 

 of the Richland Sandstone division. Traced northeastward the conglomerate 

 becomes finer grained, is very much cross-bedded, is interbedded with layers 

 of sandstone, and eventually becomes, near the Colorado, a conglomeritic 

 sandstone with thin layers of conglomerate. East of Deep Creek a portion 

 of the Rochelle Conglomerate is buried beneath the Cretaceous, an eastern 

 extension of the Brady Mountain Cretaceous beds, and it is in this buried 

 portion that the change from conglomerate to conglomeritic sandstone takes 

 place. Where it is again uncovered east of Milburn it is difficult to separate 

 the Rochelle Conglomerate from the upper layer of the Richland Sandstone. 

 Northeast of here the conglomerate bed becomes less distinct, but it may be 

 traced as a distinctly conglomeritic sandstone band across Pecan Bayou to 

 the Cretaceous. 



The entire area of the Carboniferous included in the Richland Sandstone 

 division, from its upper bed, the Rochelle Conglomerate, to the Lower Car- 

 boniferous, is barren of coal measures. Thin seams of coal may possibly be 

 found, but no beds of a paying nature are to be expected in this formation. 

 A condition of rapid deposition with abundance of coarse sediment, accom- 

 panied by a gradual subsidence, seems to have prevailed. That coal plants 

 were growing on the neighboring lands is proved by their presence as casts 

 in the sandstone, and undoubtedly thin seams of coal and carbonaceous shale 

 will be found; but the conditions which favored the accumulation of coal 

 beds had not yet arrived. 



With the close of the sandstone era, as marked by the deposition of the 

 Rochelle Conglomerate, a condition of quiet water and finer sediment pre- 

 vailed. With the new conditions a new series of beds began to be formed, 

 and for these I propose the name u Milburn Shales." The southwestern ex- 

 tension of these shales is hidden beneath the Cretaceous of Brady Mountains, 

 but in the neighborhood of Milburn they are well shown. They are capped 

 by limestone and underlain by the Rochelle Conglomerate. Near the head 

 of Deep Creek the lower layer is shaly sandstone with a thickness of 60 feet. 

 This shale grades from the conglomerate below to an argillaceous shale 

 above, and is overlaid by a deposit of clay 15 feet thick, with scattered nod- 

 ules of clay ironstone. Some gypsum is also present in this layer. Above 



