114 



CARBONIFEROUS LIMESTONES 



beneath it. The same limestone which is found on Sugar Creek, near its mouth, 

 forms the bed of the river at Ottumwa, and the rapids below that place. 



At Dam No. 15, on Section 9, Township 72 north, Range 14 west, white and 

 yellow sandstones extend four to six feet above the water-level, with alternations 

 of limestone and shale, as above represented on Section No. 25, D. The middle 

 beds of limestone contain Spirifer striatus, Terebratula sacculus (?), Terebratula 

 Roissyi, and an undetermined Terebratula. The shelly beds contain Procluctus 

 cora, and another Productus nearly related to it. 



On Section 5, Township 72 north, Range 14 west, the river runs over smooth 

 ledges of limestone, which are seen above the water-level on Section 6, as well as 

 below the mouth of Avery Creek, in the southwest corner of Section 30, Township 

 73 north, Range 14 west, at which place it has a very irregular fracture, and rough 

 surface, the edges being stained with a metallic oxide, probably manganese. This 

 rock appears to be the same bed that forms the upper portion of Section No. 25, D. 

 The strata rise about six feet between the mouth of Lower and Upper Avery 

 Creeks. On Section 22, Township 73 north, Range 15 west, six feet of limestone, 

 containing Spirifer striatus, and Terebratula sacculus, rest on marl ; one of the layers, 

 six feet above the water-level, is oolitic. There is said to be a thick bed of coal on 

 Rocky Run ; which, hoAvever, I had no opportunity of examining. 



At Dam No. 17, the Des Moines has a rocky bottom of limestone, which just 

 shows itself above the water-level, and rises six feet above it on Section 17, half a 

 mile further up overlaid by sandstone. The top of the marl-bed is also seen here, 

 about eight feet above the river. The exact position of the sandstone is not clearly 

 seen, as it lies in loose slabs, somewhat out of place. 



Three miles beyond Eddyville, in the bluffs of Muchakianock Creek, near the 

 line between Sections 19 and 30, Township 74 north, Range 15 west, is Morgan's 

 coal-bank ; here there are about four feet of tolerable coal, with only a few inches 

 of shale between it and the overlying sandstone, the whole resting on argillaceous 

 shale. This coal-bed seems to correspond with the upper one on Sugar Creek ; if 

 so, it increases in thickness and improves in quality towards the northwest. Coal 

 has been discovered also on Bluff Creek, and other places in the vicinity, and is 

 probably the same bed. 



This coal, though applicable to ordinary purposes, is not of a quality sufficiently 

 pure to enable the blacksmith to work up and weld steel with it. 



Thin beds of limestone are exposed on the right bank of the Des Moines, above 

 Eddyville. At Dam No. 18, sandstone extends from the water's edge to three or 

 four feet above, with an undulating dip, overlaid by three or four feet of limestone 

 similar to that found at Dam No. 15. 



On Section 1, Township 74 north, Range 17 west, a light gray limestone is 

 exposed, stained of a flesh-colour in the joints ; in it I found the defensive fin-bone 

 of a fossil fish, but it was not sufficiently perfect to enable me to make out the 

 species. No sandstone is seen here ; neither has any coal yet been discovered 

 nearer than Bluff Creek, on Section 14, Township 74 north, Range 17 west. 



The middle divisions of the coal-measures gradually decline above the last 

 section, so that the upper division extends within twenty-five feet of the water- 



