556 THE JOURNAL OF GEOLOGY. 



Coastal slope. Llano Estacado. 



2 b Reynosa 

 Pliocene 2 a Lagarto 



2 Lapara Blanco 



Miocene 1 a Goodnight 



1 Oakville Loup Fork 



MIOCENE. 



The Loup Fork beds of the Llano Estacado are com- 

 posed of alternating beds of bluish and almost pure white 

 sand, capped by a conglomerate of siliceous pebbles in white 

 sand matrix. In areal extent the} T are found overlying the Trias- 

 sic of the Plains throughout its northern portion, but extending 

 to the south only as far as Mulberry canyon. The fauna, as 

 described by Cope, 1 in addition to a number of species hitherto 

 found only in beds of the Loup Fork terrane, and thus fixing the 

 age of the Texas bed, contained two new forms : Protohippus 

 pachyops, Cope, and Procamelus leptognatlius, Cope. 2 



On the Coastal slope the Frio beds of the Eocene are suc- 

 ceeded by a series of deposits, which in a general way resemble 

 the underlying Fayette sands, and have hitherto been regarded 

 as a part of those beds. While it is possible to distinguish 

 between them, the differentiation is complicated in many instances 

 by the overlap of still later beds largely derived from both these 

 and the Fayette, and therefore bearing a very close resemblance 

 to them lithologically. 



The deposits are those of rapid currents of shallow water. 

 Grits and coarse sand, cross-bedded, 3 with some beds of clay but 

 oftener with balls, nodules or lenses of clay imbedded in the grit. 

 Some of the sand forms a sandrock which is apparently firm and 

 hard, but much of it is so feebly coherent as to fall apart on a 



'Fourth Annual Report, Geological Survey of Texas, Part II., pp. 18-40. 



2 Professor W. B. Scott regards these beds as equivalent to the Archer beds of 

 Florida, which Dall, for stratigraphic reasons, places in the Pliocene. Bull. Geol. 

 Soc. Am., vol. ii. p. 595. 



3 Cf. Loughridge, Tenth Census of the U. S., Cotton Production of the State of 

 Texas, p. 21. 



