AND COAL-MEASURES OF IOWA. 109 
Passing from Farmington to Bonaparte, there is a rapid rise of the strata. Al- 
ready, at Dam No. 4, the cellular magnesian limestone (6’) appears above the 
water-level; and, in the quarries below Bonaparte, the shell-beds (e’), charged 
with small Spirifer striatus, are found from fifteen to twenty feet above the water- 
level; while at twenty-two to twenty-three feet numerous elliptical stems of Platy- 
crinus, such as occur on the Mississippi, at the Keokuk Rapids, present themselves. 
These are associated also with the same species of Cyathophyllwm, Ancella, and 
Gorgonia, that characterize the rocks at the last-mentioned locality. 
Just below Bentonsport, the different members of the lower series of carboni- 
ferous limestones rise to more than 80 feet above the river; the geodiferous beds 
(a’) of the upper series only capping the tops of the hills under the sub-soil. 
The strata near the middle of this section (No. 11, D) are charged with Orthis 
umbraculum, while Archimedes and Spirifers are most abundant in the upper 
ledges. 
At fifteen feet from the base of the Seiki, a chert-bed, eighteen inches thick, 
separates the Orthis beds from white, crystalline, encrinital limestone (containing 
Spirifer striatus) lying beneath. 
At several localities in Van Buren County, four or five miles from Bentonsport, 
in Township 69 north, Ranges 8 and 9, beds of coal have been discovered, varying 
in thickness from twenty inches to two feet. That which was esteemed the best 
by the blacksmiths, in 1849, was the bed owned by a Mr. Jackson, and the coal 
procured on the west side of the waters of Bear Creek, owned by Messrs. Davis, 
Thomas, Leech, and Christian. 
At the quarry, one mile above Bentonsport, on Section 33 or 34, Township 69 
north, Range 9 west, a gravelly sandstone is found, like that in Slaughter’s Branch, 
at an elevation of about seventy feet, underlaid by chert and marly beds. The 
magnesian quarry rock is also seen here at a little lower level, with a band of 
angitlueainae rock (that has the appearance of hydraulic cement rock) intervening 
between it and the marly limestones. Three miles above this quarry, the gravelly 
sandstone is only thirty-three feet above the water-level, and separated from a 
fragmentary limestone by eighteen inches of marlite. At two separate locations, 
below Keosauqua, one on the west, and the other on the east side of the Des 
Moines, the cellular magnesian limestone is twenty to twenty-five feet above the 
river, overlaid by concretionary limestone ; as may be seen by inspecting Section 
No. 12, D. 
At Gillis’s coal-bank, on the east half of the southwest quarter of Section 32, 
Township 69 north, Range 9 west, about two miles below Keosauqua, these same 
beds are seen, at a little lower level; the pebbly sandstone being near the water- 
level. Over the upper concretionary limestone are ferruginous clays, and on these 
rests a coal-seam, eighteen inches in thickness, as shown in Section No. 13, D. 
This seems to be the lowest coal-bed in the Des. Moines Valley, and lies about 
twenty feet above the concretionary limestone /’. 
Beds of coal have been observed at various localities in the vicinity of Keosauqua. 
The best, however, is said to be obtained between the Des Moines and Skunk 
Rivers, in the neighbourhood of Fairficid, on the waters of Walnut and Cedar 
