C. A. White on the Iowa Coal-measures. 333 
members being absent. Leaving the Iowa, and going west- 
ward to the Boone and Des Moines rivers along the northern 
border of the coal field, we find at Webster City in Hamilton 
county, and at Fort Dodge in Webster county, the Coal-meas- 
ures resting again immediately upon the St. Louis limestone, 
while the equivalents of the Kinderhook beds are found coming 
up to the surface northward of those localities in Pocahontas, 
Humboldt and Franklin counties. Thus it will be seen that if 
we except the absence of all the rocks of the Chester lime- 
stone epoch, the only real unconformability of the Coal-meas- 
ures, so far as we now know, consists of the overlapping of the 
northeastern corner of the coal field from the St. Louis lime- 
stone upon the Kinderhook rocks. We also see that there is 
still greater unconformability among the members of the Sub- 
carboniferous period themselves. 
The characters, both paleontological and lithclogical, of the 
St. Louis limestone, remain almost unchanged from the 
northern to the southern limits of its extension in the State, a 
distance of two hundred miles. The trend of its eastern and 
northern border evidently does not partake of the angle whic 
the outline of the coal field forms in Hardin and Marshall 
counties, but conforms more nearly with the older formations 
in that respect. 
The characters of the Kinderhook beds are more changed as 
which is referred almost without hesitation to the oolitic mem- 
ber as seen at Burlington. The limestone of its most northern 
extension is also principally ooliti 
Li tic. 
n view of the foregoing facts the following conclusions are 
dL 
-and grad 
southwestward. At the close of that e 
of Johnson county. 
until the close of the 
