134 



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 semireticidatus, 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, 0. 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 

 a light gray and compact productal limestone. Some of the other beds are filled 



