152 
the tertiary geology of the 
According to 
c -i^c «hnvp Texarkana, on the Arkansas frontier, and taking a generally 
:: :c*n:dL.ion_passing „t or near aarksvn.e (^d Krver Co., Cordcana 
(Navarro Co.), Marlin (Falla Co.), Cameron (Milam Co.), Elgin (Bastrop CoO, Scguin 
Guadeloupe Co.), and the northwest eorner of Ataseosa-erosaea the Rio Grande at 
almiit the mouth of Las Moras Creek, a little south of the Pecos Rtver, and to the 
north of Eagle Pass.* c a . • 
TJ.e westerly deflection indicated as beginning a few miles south of San Antonio, 
and e.xtending to the Kio Grande, can scarcely be said to be definitely proved as yet, 
although Loughridge affirms t that “the glauconitic sandstones, mentioned by Mr. 
Schott as occurring along the river [Rio Grande] from the Cretaceous rocks at the 
mouth of Las Moras Creek, north of Eagle Pass, southward to Roma, near Rio Grande 
City, are doubtless of Tertiary age.” Further evidence is needed on this point, however, 
although some confirmation of the supposition is lent by the discovery of fertiarj' 
fossils {Cartiifa y>?rt«icos<a, among others), in a locality, Arroya las Minas, situated 
between El Paso and Leon (where 1) + 
Among the common Tertiary fossils occurring in Texas Ruckley identifies § Ostrea 
BeUo'formis, Peden LyelH, Astarte Conradi {= young of Crassatella alto), Cardita 
jdanit-osta, and TiirriteUa curinafa; and there can be but little doubt, as claimed by 
Huckley, that the Eocene of Bastrop, Robertson, and Leon counties, and thence along 
tlie eastern border of the Cretaceous, northward to Red River County, belongs, if not 
mostly, at least in considerable part “ to the lower Eocene, as seen at Claiborne, 
Alalmma, and in Clark County, west of Claiborne.” How much of it belongs to the 
true “ ( laibornian,” .still remains to be determined. luoughridge states that “the 
Claiborne group of white lime.stones and fossils has not been recognized in Te.xas;” 
the word “ Claiborne ” probably here stands for either “ Jackson ” or “ Vicksburg,” 
although there can be little, if any, question as to the existence of both of these 
formations, if nowhere else, at any rate along the Louisiana boundary.|| 
t PP. 18,21, 1882, fo.mingpa.tofyol.yoftl.e Tenth Census Repo.te. 
I The series of ,1 y Report. § First Annual Report, p. 64. 
Iv) from WUiculock RoliertsT^^e ^ Gabh in the Journal of the Academy of Natural Sciences (new ser., vol. 
fm'm any hitherto found in tl ^ ’ f Caldwell County, although comprising many forms (piite distinct 
The author has been able to idenli/ f ®t‘c\v forms recalling a newer horizon. 
County, almut 50 miles southeast of artesian well-boring in Palestine, Andersen 
540-610 feet (or 50-120 feet below fVi ™ °'^***^P of the Eocene, and from a depth beneath the surface of 
TurM carinata ^ to Cardita planiccs, a. Valuta Sayana, and 
TurrittUa earinafa and other Clailinrn f *1“* iorin known as G. dennata, associated with 
Laredo, on the Rio Grande, and he haK*'T' detected by the author in limc-stone blocks from 
■VamaeU and Tere^ra pliHftra from AtaJlotl'^pr , ’ f fonns, Pleuroloma platyaoma, Fwm* (Streptidura) 
ftcqueutly refcrrvd to by geologists is in reality an alin'd improbable that the Cardita planicosta 
Hr Lou-hridge, who, more than any other geologist, has closely 
of the different formations occurring throughout the State, 
