OF THE MISSOURI RIVER. 



135 



with a striated and plicated Orthis, like 0. 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 tubcrculatus, Productus cora, Spirifer fasciger (?), Terebratula plano- 

 sulcata, and Orthis umbracidum. 



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 Elizabeth town 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 Fusidina 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 Fusidina 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 Helix tliyroideus, H alternata, H monodon, H. fraierna, Heli- 

 cina occulina, Pupa armifera and Succinea campestris (?). 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 



