144 
Teansactions Texas Academy of Science. 
Hill^ Egbert T. 
it is evident that the Cross Timhers cannot represent any posit-Cretaceous 
sediments, 
* * * ^ * * * 
“'G-eologically, the area occnpied by these timbers [the Lower Cross Tim- 
bers] eonsisits of a series of coarse, friable, arenaceous sandstones, alternat- 
ing with clays, whose position is beneath the shales, and limestones; and, 
like them, its western projecting margin is constantly wearing .away. The 
unique fauna, now being studied by iDr. C. A. White, and the presence 
of lignites, indicate that the sediments are those of shallow waters; they 
resemble basal groups of the cis-Mississippi region, and. Dr. White believes, 
the Dakota sandstones of Kansas, )Elsewhere than in Texas this group 
would be considered the base of the Cretaceous; but such is noit the ease 
here, for it clearly rests upon four hundred feet of a second and lower 
series of limestone strata, and one that was greatly eroded before these 
sands were deposited. 
* * -jf •)«■ * * * 
“On descending the escarpment at the western edge of the Orand Prairie, 
we reach the sandy soil of the Upper (Cross iTimbers. A geologic section 
will show that the surface soil is detritus of the underlying strata, which 
dip to the east, under the adjacent limestone prairie. This series of sandy 
strata varies in structure as we descend them. The upper strata abound 
in Dinosaurian bones and teeth, the lower in Lepidodendrons and Cala- 
mites. They mark the contact of the basal iMesoaoic and the Carbonifer- 
ous. 
“The sands of the eastern half of the Upper Cross Timbers are purely 
^ siliceous, fine-grained, and utterly free from any cementing matrix. They 
are so friable that they quickly lose all appearance of original stratifica- 
tion on exposure, and were it not for railroad-cuts and well-borings through 
the overlying Cretaceous limestone, their true stratigraphic position would 
still remain obscure. The pure white sands of this series can be traced 
along the eastern border of the Cross Timbers for over a hundred miles. 
These sands' constitute the receiving reservoir for the artesian wells of 
Port Worth and Dallas, their strata dipping at such an angle under the 
Grand Prairie that they are reached at a depth of 350 feet beneath the 
first named place, and about 750 at the latter.” 
198. 
'The Texas Section of fhe American Cretaceons. 
Amer. Jour, of Science, III, Yol. XXXIY, pp. 287-309. Xew 
Haven, Oct., 1887. 
Introduction: The Cretaceous Areas of the United ^States. Great simi- 
larity of the molluscan faunae, with varying lithologic characters. Loose 
use of the term “groups,” which “are really ‘horizons’ representing the 
culmniation of species or sedimental variations. 
****■«■** 
“If the Lower Cross Timber sands be of the age of the Dakota sand- 
stone, as has been ascertained by Shumard and others, and since when 
present they rest directly on top of this division, then we have in Texas 
