CARBONIFEROUS FOSSILS—COAL-MEASURES. 
63 
rock with a hammer. Of the fossils from Pecos, which have been described and figured, two 
are new : Spirifer pilosus, PI. II, Pig. —, and Terebratula millipunctata, PI. II, Fig. —. Both 
these and the other important species have been most beautifully and accurately drawn for me 
by Mr. F. B. Meek, whose labors in geology and palaeontology are well known to American 
geologists. 
The occurrence of Productus semireticulatus at this new locality in the centre of the country 
is very interesting, inasmuch as this is one of the most widely distributed carboniferous fossils 
known, it having been found in various parts of Europe, in Asia, South America, and Austra¬ 
lia. It was also found near Fort Laramie by Captain Stansbury. Terebratula roissyi is another 
fossil which has a wide distribution. 
Carboniferous sandstone and coal-measures .—At nearly all the points where the carboniferous 
limestone is exposed, it is overlaid by thick strata of sandstone and shales in conformable strat¬ 
ification. These strata were found most developed, and reaching their greatest thickness and 
extent, at the eastern end of the line. The hills and ranges seen in passing up the Arkansas 
are all formed of this group of rocks. According to Dr. Shumard, the sandstone is the pre¬ 
vailing rock between Fort Smith and Fort Belknap, and, during the exploration of the Red 
river by Captain Marcy it was found in extensive outcrops. 
Lithological characters. —The observations which Mr. Marcou makes in his notes upon the 
mineral character of this group along the line are not numerous or full, nor are the different 
outcrops represented in the collection by specimens. It appears, however, that the prevailing 
color of these rocks is grey, or yellowish-grey, and that they are formed, at least along the 
Arkansas, of thick beds of compact sandstone, alternating in some places witli clay shales, 
which are sometimes blackened by bituminous matter, or contain distinct beds of coal. Ac¬ 
cording to Dr. Gr. C. Shumard, who has carefully examined the strata near the line in Arkansas 
and southwesterly to and beyond Fort Belknap, the sandstone is often highly charged with 
iron, and varies in color from a light grey to a dark brown. It is found in heavy massive beds 
made up of coarse quartzose grains, and is intercalated with finer-grained sandstone, which is 
sometimes beautifully ripple-marked. “ It corresponds in its lithological features with that 
forming the Ozark range of mountains.” 1 Mr. Marcou states that the beds of sandstone at 
the mouth of the Poteau river are associated with beds of marly shales, which are blackish in 
the lower portions. The stratification is very distinct, but the sandstone decomposes where 
exposed to the air, and is friable ; it is also so much filled with fissures that it is not easily 
BLUFF OF CARBONIFEROUS SANDSTONE AND SHALE. 
worked. Twelve miles south of that point a bed of bituminous coal is found. (Notes, June 
19.) At another place, he mentions that the sandstone at the mouth of the river is highly 
fossiliferous, and a bed of fifteen or twenty inches thick is yellowish-grey, and contains bitu¬ 
minous black spots and nodules of oxyd of iron. It is also ripple-marked. 
1 Shumard. Marcy’s Report. Red river, p. 180. 
