382 Texas in tts Geognostic and Agricultural Aspect. [June, 
parts of the undulating Hill-country are found masses of petrified 
wood. As Roemer already correctly concluded, this belongs to 
the tertiary formation ; and we can, therefore, by this means de- 
cide with certainty upon its presence there. The immense pro- 
portion of silex in this formation has petrified the wood, instead 
of carbonizing it. 
On the bank-slopes of the Red river, near Shreveport, I found 
a layer one to two feet thick, which was half carbonized, and half 
petrified ; and in the same stratum lay large logs of cypress ina 
half carbonized and half petrified state. 
The large deposits of iron-ore in the tertiary formation of 
Eastern Texas may become of somewhat more importance than 
the coal in the Hill-country, but they by no means equal in value 
the ore-deposits of older origin. The iron is here found mainly 
_as iron sandstone, and in many counties, as in Henderson, Ander- 
son, etc., in such quantities that whole ranges of hills are formed 
of it; and the region presents many times, by their rocks and the 
ravines between, a quite romantic character; this is particularly 
the case with the so-called big rocks betwedlh Vanzandt and.Hen- 
derson counties. The tertiary formation is also rich in salt de- 
posits, and in many places the salt is successfully obtained from 
salt-springs. In the iron regions we encounter in some places 
very strong mineral springs, especially sulphur-springs. They 
hold in combination much carburetted hydrogen gas and sulphu- 
ret of iron; when they come to the surface, they liberate blackish 
gray and yellowish precipitates of sulphur and sulphuret of iron ; 
but they do not come from any considerable depth like thermal 
springs, since they have nearly as low a temperature as the ordi- 
nary springs of the neighborhood. On the Neches river, as well 
as on the Sabine, I found larger deposits of a blackish-iron sand- 
stone, which was quite loose and brittle; it holds iron mostly as 
sulphuret of iron, Owing to its slight coherency, the latter may, 
through several influences, be easily decomposed, and then on 
the one side give cause to the sulphur springs, and on the other 
to the sulphate of iron produced in that region. There aré also 
many beds of clay, which contain alum, or bittersalt, and impart 
for this reason a strong taste to water; in particular places, in 
summer, there is seen in the bottom of tumblers, after the evapo- 
ration of the water, a white crust of this salt. Of eee nih 
tance to mining in Texas are the Highlands. 
