Some Geological Problems — Calvin. 27 
shall find, a short distance above the mouth of Pine creek, an 
exposure of yellowish sandstone with interstratified shaly beds. 
The position of this sandstone leaves no doubt as to its relations 
to the Hamilton limestone. Althonc^h along the river the con- 
tact is not seen, the sandstone is evidently superimposed on 
the limestone. 
The relation of the sandstone, coupled as it is with an entire 
change of lithological characters, led Hall to refer it to the 
Chemung period,* and a fossil spirifer that occurs abundantly 
in the form of internal casts in one of the layers, is described 
as a new species under the name of Spirifer capaxf and oc- 
cupies a conspicuous phice among the figures of species supposed 
to represent the Chemung fauna of Iowa. 
A yellowish sandstone resting upon greenish shales occurs in 
the bluffs along the river at Burlington. This sandstone con- 
tains casts of brachiopods in abundance, but it does not contain 
a single specimen of Spirifera capax. Nevertheless Hall re- 
gards the Burlington sandstone as the equivalent of the spiri- 
fer-bearing sandstone of Muscatine county, and refers it like- 
wise to the age of the Chemung group of New York. J 
Thus matters stood until Meek and Worthen, in a paper on 
the Goniatite limestone of Rockford, Indiana,§ proposed the 
name Kinderhook group to include, not only the Goniatite beds 
in question, but the yellow sandstone at Burlington and all the 
equivalent strata of the Mississippi valley that had previously 
been referred to the age of the Chemung. Furthermore a study 
of the Kinderhook fauna at Burlington, near the town of 
Kinderhook in Illinois, at Rockford, Indiana, and at other lo- 
calities where the formation is typically developed, showed that 
the Kinderhook group is not only not Chemung, that it is not 
Devonian at all, but that it is related to the strata above it rather 
than to those below it, and must therefore be transferred to 
the Carboniferous series. Accordingly Meek and Worthen in 
their reports on the geology of Illonis,|| have placed the Kinder- 
♦Hall's Geology of Iowa, vol i, Part i, p. 89. 
fid., vol. I, Part ii, p. 520, Plate vii, figs. 7 ad. 
JHall's Geology of Iowa, vol. r, part i, p. 89 et. seq. 
§Am. Jour. Science, vol. xxxrr, No. 95, Sept. 1861. 
IIGeological Survey of Illinois, vols, i-vrr. See particularly vol. r, pp. 
44 and 118. 
