154 CARBONIFEROUS ROCKS 
costatus and P. Flemingii ; another is a complete agglutination of Fusulina cylin- 
drica, in a very perfect state of preservation. 
The aggregate made up of this highly interesting little foraminiferous shell has 
so much the appearance of concreted small grain, that some of the inhabitants of 
the country, to whom I pointed out the rock, could hardly be persuaded that it was 
not petrified wheat. . 
Up to the time of its discovery, during this survey on the Missouri, I believe it 
had never been observed in the United States, except in a siliceous stratum near 
the base of the coal-measures of Ohio; and in Europe, only in the Carboniferous 
Limestone of Russia. 
The same species of Chonetes which occurs above the mouth of Keg Creek, is also 
common at the same locality. 
Alternations of regularly bedded limestones and shales can be traced between 
Fort Kearney and the Nishnabotna for ten miles. In the bluffs skirting the nar- 
rows of the Nishnabotna, the purple shales are conspicuous, resting on greenish 
micaceous sandstones, with vegetable impressions. At the base of the shales, and 
between them and the sandstones, a bed of dark-coloured limestone is intercalated, 
containing Productus semireticulatus, and, beneath it, bituminous shale and an imper- 
fect seam of coal. The carboniferous strata of the Nishnabotna form the bases of 
hills varying from two hundred to two hundred and fifty feet in height, presenting 
an outline similar to those represented on page 132, and composed, in a great 
measure, of the same fine ash-coloured marl found to prevail at Council Bluffs, and 
which is doubtless a continuous deposit, above the carboniferous rocks and drift, all 
along the highlands of this part of the Missouri. 
Above Fair Sun Island, micaceous sandstones are seen at the height of from 
thirty to forty feet, with some calcareous intercalations, underlaid by black bitumi- 
nous shale and brown encrinital limestone. (Section No. 32, M.) 
Just below the mouth of the Little Nemahaw, on the right bank, a section of 
about thirty feet (No. 31, M) consists chiefly of red schistose sandstone and argil- 
laceous layers, with a band of light gray limestone towards the top, one foot thick, 
and a dark gray and brownish limestone, containing, in great abundance a small, 
undescribed Spirifer, of the same species as that collected near Keg Creek; also 
Orthis crenistria, O. eximia, and Chonetes semiovalis. 
In the bend of the Missouri, half a mile lower down, on the same side, heavy 
beds of pyritiferous, argillaceous shales, and four to five feet of black bituminous 
shale, are exposed, six feet above the water-level, associated with large slabs of pro- 
ductal limestone, which seem to originate in bands under the shale, in nearly the 
same succession as shown on Section No. 31, M. No coal shows itself, but there 
is said to be a bed beneath the water-level, below the Little Nemahaw. The person 
from whom I derive my information may, however, have mistaken the black shale 
for coal. 
Sixteen miles above the mouth of the Tarkio (at Section No. 30, M), purple and 
gray shales alternate with limestone. The upper calcareous bed is about two feet 
thick, and lies at an elevation of twenty-five feet. The bed near the water-level is 
alight gray and compact productal limestone. Some of the other beds are filled 
