IOWA, AND WAPSINONOX RIVERS. 87 
and interrupts the continuity of the strata for the distance of about fifty paces. 
On crossing this hollow, a soft brown sandstone, several feet thick, with vegetable 
impressions, is exposed, in a low arch, fifteen feet lower than the top of the limestone. 
This appears to be another outlier of coal sandstone, so frequently met with in this 
portion of the Iowa River; which, by a fault or slip of the beds, has sunk into a 
depression. Thirty paces beyond the sandstones, up stream, the white limestone is 
again in place, at nearly the same elevation as the sandstones. In the two adjacent 
exposures of limestone there are no intercalations of sandstone. 
About two miles and a half from Iowa City, on Section 36, Township 80 north, 
Range 6 west, of the 5th Principal Meridian, a schistose, marly limestone, about 
twenty feet thick, is exposed on the east bank of Rapid Creek, opposite Falkner’s Mill, 
surmounted by a decomposing bed, from which loose corals of the following genera 
and species have become detached, and lie scattered on the surface: Lithostrotion 
hexagonum (2), L. ananas, Cyathophyllum turbinatum, C. ceratites (2), C. dianthus (2), 
O. vermiculare (?),Cystiphyllum Devoniensis, Cheetetis (species undetermined), and 
Favosites polymorpha. The beds beneath contain chiefly shells of the following 
species: Zerebratula reticularis, Orthis resupinata, Spirifer euruternes, and Terebra- 
tula concinna (2). 
On the same creek, on Section 30, Township 80 north, Range 5 west, of the 5th 
Principal Meridian, sandstone with vegetable impressions occurs, in a similar position 
with reference to the coralline limestone as near Iowa City. 
On Section 4, Township 79 north, Range 6 west, of the 5th Principal Meridian, 
two or three feet above the level of the Iowa River, limestone is found containing 
coralline beds similar to those near Iowa City; the latter extending to the height 
of from twelve to fifteen feet. 
In ascending the Iowa, the above-described limestones occur at intervals for the 
distance of about twenty miles, by the meanders of the river, and twelve to fourteen 
miles in a direct line. 
The principal exposures are as follows: Near the line between Sections 32 and 
33, Township 80 north, Range 6 west, of the 5th Principal Meridian, on the west 
side of the river; above, and below the mouth of Newcomb’s Creek, on Sections 33 
and 34, same township and range, on both sides of the river, having a slight westerly 
dip; on Section 27, Township 80 north, Range 6 west, in a cliff of about 27 feet, 
on the left bank, where the strata dip 3° or.4° to the southwest. Here some of the 
beds are full of fossil shells, viz.: Zerebratula aspera (very abundant), Terebratula 
reticularis (large variety), Orthis resupinata, Spirifer euruteines ; Spirifer with a 
highly extended cardinal area, measuring sometimes five inches angle to angle, 
which we have described in the Appendix; Leptena (sp. ?), Phacops macrophthalma, 
several reticulated lamellif rals, Cyathophyllum ceratites (?). It is at this locality 
that much of the rock used in the construction of the State House has been pro- 
cured. The lower beds are rather schistose, but the upper are more solid and 
substantial, and may be obtained in blocks of from nine inches to two feet. The 
upper eight feet contain but few fossils. 
On the opposite side of the river, on Section 22, same township and range, rocky 
ledges, of from thirty to forty feet in thickness, are exposed for three-quarters of a 
