OF THE MISSOURI RIVER. 135 
with a striated and plicated Orthis, like O. eximia. Near Antelope Island, the 
strata are much of the same character, except that the limestone is much more 
ferruginous, and the joints are filled with carbonate of iron. 
At the mouth of the Great Nemahaw, soft gritstones present a perpendicular 
wall of twenty to twenty-five feet to the river. The lower beds are of a greenish 
hue; the upper, of buff colours. (See Section No. 28, M.) At the base of these 
hills, a short distance below, are two bands of limestone, with a deposit of argilla- 
ceous iron ore between them. 
Opposite Iowa Point, in the next bend of the Missouri, a good Section, No. 27, M, 
is exposed, of fifty feet, consisting of variously tinted argillaceous and bituminous 
shales, with intervening bands of limestone; the latter being more abundant than 
in the sections above. A gray layer of limestone, towards the base of the section, 
yielded Nautilus tuberculatus, Productus cora, Spirifer fasciger (?), Zerebratula plano- 
sulcata, and Orthis umbraculum. 
From a comparison of the various sections obtained between Keg Creek and 
Iowa Point, it appears that the most inferior of the carboniferous strata of the 
Missouri are the purple, gray, and black bituminous shales, dark productal lime- 
stones, and micaceous green and brown sandstones, which are best displayed in the 
sections near the narrows of the Nishnabotna, and the confluence of the Great 
Nemahaw. 
Four to five miles below the mouth of Little Tarkio River, the bluffs approach 
the left bank, and present the first section which I encountered immediately on the 
river, on that side of the Missouri. It consists of light-coloured limestones, contain- 
ing but few fossils, and apparently overlying the shales, shown in the Iowa Point 
Section (No. 27, M), and which are seen at intervals, as far as Elizabethtown and 
the mouth of Nodoway River, in the form of benches; also as confused heaps and 
broken slabs lining the shore. 
Four to five miles above St. Joseph’s, the buff-coloured Fusulina bed, similar to 
that observed near Keg Creek, occurs (Section No. 26, M); its elevation is about 
sixty feet above the bed of the river, overlying a continuous rugged bench of light- 
gray, cherty, concretionary limestone. The lower portion of this section consists of 
alternations of limestone and shales, partially concealed by vegetation, such as have 
been described as forming the Fort Kearney section. The bench of concretionary 
limestone is about eight feet thick, and appears in the form of an artificial terrace- 
wall, traceable for several miles, with a southerly dip; this brings it within fifteen 
feet of the water-level, twenty miles below St. Joseph’s, where it is seen resting on 
shales. The buff-coloured Fusulina bed accompanies it throughout the greater part 
of this distance. The bluffs at St. Joseph’s are composed almost entirely of the 
same fine, light-yellow, marly loam, that has been spoken of as forming Council 
Bluffs. In it I found Helia thyroideus, H. alternata, H. monodon, H. fraterna, Heli- 
cina occulina, Pupa armifera and Succinea campestris (2). At this locality, the 
deposit is at least one hundred and fifty feet thick, and extends almost to the 
water's edge, resting on gravel; the whole being underlaid by carboniferous argilla- 
ceous shales. (Section No. 25, M.) 
The evidence of the equivalency of the marly loams of the Missouri and Wabash 
