34 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
In making this section I found about half a mile above the mouth of 
. the creek, in a vertical bluff some twenty feet in height and probably 
three hundred feet in length, the following exposure: 
1. Soil. 
2. Yellow sand. 
3. Brownish yellow sands with little clay, containing large quantities of 
plant impressions, roots or stones, converted into earthy browncoal, spiral 
rootlets, etc. 
4. Browncoal, somewhat lignitic in places but generally compact and 
massive. 
5. Volcanic dust, white to creamy white in color, with traces of roots or 
worm borings and a little sulphur. 
6. Browncoal, somewhat variable, with small inclusions of members of 
the group of asphaltums. 
7. Gray clays and sands, interbedded or interlaminated, weathering yel¬ 
low, with effloreseuce of sulphur on surface. 
Under the microscope the material of No. 5 shows all the character¬ 
istics of volcanic dust, but the individual grains are much larger or 
coarser than those I have observed previously in other portions of the 
area. 
Were it not for the fact that we have a similar series of lignites oc¬ 
cupying relatively the same position to the upper sands as shown in 
the section of Second Chalk bluff already referred to, and were it not 
for the further fact that the section made was from a continuous ex¬ 
posure in which the connection was not lost or even obscured at any 
place, and that no faulting of any consequence was found, it might be 
argued that the series of lignites and volcanic dust were of later age 
than the upper sandstones and had been deposited in this valley sub¬ 
sequent to its first erosion. 
The facts, however, clearly demonstrate that the stratigraphic posi¬ 
tion of this bed at least is in the browncoal series of the Fayette beds, 
and, if our correlation of these beds be correct, of Miocene age. 
These deposits are locally known as “ chalk,” and are used as such 
in marking lumber, etc., and also to a less extent for polishing pur¬ 
poses. 
