COAL AT FORT BELKNAP. 31 
IT. COATL. 
Fort Belknap.—Carboniferous formation.—Lignite on the Brazos.—Probable extent of the coal. 
The only locality of coal mentioned in Captain Pope's report is that at Fort Belknap, on the 
Brazos, and which has already been noticed in a general way (p. 27). There are no specimens 
of this coal in the collection, nor of any other from other localities. I learn, however, from 
Col. Loomis, the commanding officer at Fort Belknap, that this coal is of fair quality and burns 
freely, leaving a white or grey ash. It does not cause any trouble by slaging. This coal has 
been in use at that post for a long time, and excavations over twenty yards deep are already 
made into the bank, on the course of the vein or bed. The vein is horizontal, and about four 
and a half feet thick, and is divided in the middle by a thin layer of slate from one to four inches 
thick. Itis found at many places along the river, and several places have been opened into, 
and good coal taken out. A layer of hard blue clay is found under the bed. An attempt to 
procure water by a well about sixty feet deep, which was made by General Belknap, at a point 
three-quarters of a mile from the river, resulted in the discovery of a bed of similar coal, which is 
probably the continuation of the same bed. When the coal was reached, the well was abandoned. 
The coal is taken from the mine in large blocks and masses, but when exposed to the air they 
fall to pieces. 
Dr. G. G. Shumard is very positive in his opinion that this coal is of the true Carboniferous 
period, and says that it is characterized by the fossil ferns of that era. "The description of the 
adjoining strata seems to indicate a more recent age for this deposit; in fact, according to the 
descriptions of the strata, they more nearly resemble Tertiary than Secondary deposits. Dr. 
Hitchcock has observed this, and in his report to Captain Marcy says: ‘‘ Now, at first view, it 
would seem almost certain that we have here a description of a genuine coal formation of the 
Carboniferous period, not less than three hundred and fifty miles long, associated, moreover, 
with those valuable iron-ores which, in other parts of the world, are connected with such 
deposits; for, in descending through the formation, we find, first, overlying shale; then, coal; 
then, coal sandstone, or perhaps millstone grit; and then, perhaps, Carboniferouslimestone. But 
itis well known that coal occurs in other rocks besides the Carboniferous, as in eastern Virginia 
in Oolitic sandstone, and in other places in Tertiary strata. These more recent coals are often 
of great value, as in Virginia, but they are not generally as good as those from the Carboniferous 
Strata. It becomes an important question, therefore, to determine to what geological period the 
coal under consideration belongs. A few specimens of the fossil ferns would decide the matter, 
and I trust that Dr. Shumard is right in referring them to the Carboniferous era; but it is well 
known that analogous species occur in the higher rocks; and so coal, even in the Tertiary strata, 
is sometimes more or less bituminous. The evidence, however, appears to me to be strong in 
favor of this deposit being of the Carboniferous age. But in your letter of April Ist,’ you state 
some facts respecting this coal that have thrown a little doubt over my mind. You say that 
‘the coal formation of the Brazos is found in a coarse, dark sandstone rock, which is a solid 
stratum, but is easily removed in consequence of being so soft. In excavating for a well, we 
passed through the sandstone and the coal. The greater part of the stone was removed with 
the mattock; and in the coal, which was here about sixty feet below the surface, we found 
fossil ferns, which, unfortunately, were not preserved.” The ease with which this sandstone 
was removed, requiring only a mattock, corresponds better with the hardness of Tertiary than 
of Carboniferous rocks; yet, in some parts of the world, distant from igneous rocks, the sedi- 
mentary strata are but little indurated.’’* i ! 
Beds of lignite or Tertiary coal are found at many places in Texas. A bed, four feet thick, 
is found on the Colorado river, near Bastrop, beneath a layer of Eocene fossils. It also occurs 
on the Brazos, at the mouth of the Little Brazos. These localities are, however, nearly two 
1 Letter from Captain Marcy. 2 Report of Captain Marcy, pp. 164, 165. 
3 Verbal communication from Dr. Moore, of Texas. June, 1855. 
