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2. Contributions to the Geology of Texas. 
thodon shells, but there are no shells different from those now 
living in the bay. Every thing tends to the supposition that 
the conditions of climate, etc., at the period when these deposits 
along the coast of Texas were formed, did not differ materially 
from the present, except that a change in the relative level of 
~Tand and sea has since taken place. 
To the diluvial period must be likewise referred the depos- 
its of clay and sand which form the banks of the Brazos and . 
probably all the other large rivers of the country. Mr. Hough, 
a gentleman residing at San Felipe, has discovered in the muddy 
banks of the Brazos near his place of residence, many fossil bones 
of extinct species of mammalia, and has made a valuable collec- 
tion of them, which I had an opportunity to examine when it 
was exhibited about two years ago at Galveston. It contains 
bones of mastodon, megalonyx (claw bones), tapir, and of a 
gigantic and undescribed species of ox.* 
To the diluvial age of the globe must be further referred 
the deposits of gravel and sand, which form a broad belt of bar- 
ren or poor land covered with pine and post-oak timber, in the 
“rolling” or undulating portion of Texas, and extending from 
west to east across a considerable part of the country. Follow- 
ing up the Colorado from Columbus to Bastrop, or the Guadaloupe 
from Gonzales to Seguin, we pass directly across this belt. The 
gravel is mostly composed of pebbles of silex evidently derived from 
decomposed cretaceous strata. Within the limits of this gravel 
formation, fossil wood of dicotyledonous trees in smaller or lar- 
ger fragments is found almost every where. In some localities 
it is particularly abundant, and whole trunks are occasionally 
met with. I have sent to Europe the lower part of a trunk, 
about three and a half feet in diameter, weighing about six hun- 
dred pounds, and showing distinctly the beginning of the ramifi- 
cation of the roots and most beautifully the fibrous internal struc- 
ture of the wood. ‘This specimen was discovered together with 
many smaller ones, in the banks of a small creek near the town 
of Boonville on the Brazos. When I wrote my former paper, I 
was not sure about the formation in which this fossil wood was 
originally deposited. I am now perfectly convinced that it is 
derived from cretaceous strata, having afterwards found pieces 
of it among cretaceous fossils at localities where for hundreds of 
miles around, there are no other but cretaceous strata, and no 
traces of diluvium or drift are met with. 
Strata, belonging decidedly to the tertiary period, I did not 
see at all during the first part of my stay in the country, and I 
was inclined almost to doubt their existence in Texas altogether, 
although this would have been against the general analogy of the 
* This Journal, volume i, ii Ser., p. 244. 
