Record of Geology of Texas, 1887 - 1896 . 
273 
White, Charles A. 
western portion of Texas more diversified than the eastern, containing few 
mountainous elevations, hills of cireumdenudation and valleys. Rocks of 
the Texan region are Cretaceous, Tertiary and Post-Tertiary. Cretaceous 
strata are limestones and sandstones more or less compact. Uncon- 
formity between Upper and Lower Cretaceous strongly marked in some 
localities. Dip of Cretaceous, east of the Paleozoic area is towards the 
Culf lO'r the Tertiary embayment; west of that !area there is a generally 
westerly dip. Structural geology. List of Cretaceous formations in Texas. 
The Laramie recognized only in western Texas, in the valleys of the Rio 
Crande and the 'Nueces. Eagle Pass beds upon which the Laramie rests 
1‘egarded as equivalent to the Ripley formation and Fox Hill strata. A 
section — ^Description of the members composing it. The Trinity formation, 
originially desiignaited asi Dinosaur iSiands. Placed pnovisiioinally with the 
Cretaceous and assigned to the horizon of the Potomac and Tuscaloosa 
Formations. The Comanche 'Series stands alone. Separated by a time- 
hiatus from the formation above and below. 'Its greatest thickness is in 
the North Mexican region. The Timber Creek Formation. Lowest strata 
of the Upper Cretaceous. Its molluscan fossils are all marine and different 
from those of the Comanche series. The Timber Creek Formation, probably 
the equivalent of Tombigbee 'Sands and possibly of the Raritan and Amboy 
Clays. The Eagle Ford Formation. Approximately equivalent to Fort 
Benton Shales and as probably equivalent to the lower part of the Rotten 
Limestone of the Uulf States and to the Clay Marl of New Jersey. The 
Austin Formiation or Austin-Diallas Chalk. Its upper layers merge gmad- 
ually into clayey or marly layers which in eastern Texas pass into strata 
that bear an abundance of characteristic fossils of the Ripley Formation. 
The “*Ripley” strata of Texas. The time-hiatus between the Cretaceous 
and the Tertiary. A comparison of the Cretaceous Formations of east and 
west Texas. Diagram showing the interrelations of the Texas Formations. 
A comparison of the Cretaceous Formations of the Atlantic and G-ulf border 
regions and the Texas Cretaceous. Diagram. 
DisicussiO'D 'O'f Mr. HilFs' piap'er oin Com'aiiichie S'eries 'O'f tile 
Texas-Arkansias Region.^’ 
Buaietm Geol. Soc. of America, Vol. II, p. 525. 1891. 
Dr. C. A. White: “The Trinity Beds, to which Air. Hill refers as lying 
at the base of the Comanche series, I have, in a work now in press, provi- 
sionally referred to the base of the North American Lower Cretaceous. 
They contain, besides some undetermined dinosaurian remains, a few species 
of non-marine mollusca; but I am at present unable to say whether these 
forms are more suggestive of Cretaceous than of Jurassic age. 
“The fossils which Mr. Hill has exhibited as coming from strata beneath 
the Comanche I am .at present unable to specifically identify. If they 
really came from the horizon indicated, I think they represent a hitherto 
unlcnown molluscan fauna, and that they are of very great interest. 
“I quite agree with Mr. Hill in the opinion that the different subdivisions 
of the Texan Cretaceous cannot be definitely correlated with subdivisions 
