ECKEL.] IOWA. 151 
While the amount of magnesia in certain of these beds is higher 
than is desirable, there is still a large amount of rock available which 
is not higher in that element than that elsewhere u±vd. It is probable 
that careful search would locate even better beds at the same horizon 
farther north. 
DEVONIAN LIMESTONES. 
There are in Iowa beds representative of both upper and middle 
Devonian. The former includes the State quarry beds in Johnson 
Count} 7 a and the Sweetla'nd shale in Muscatine County/' The larger 
portion of the Iowa section belongs to the middle Devonian, which 
may be divided into three formations — the Lime Creek, Cedar Valley, 
and Wapsipinnicon. In various counties these formations have been 
subdivided and individual members have been mapped. The Lime 
Creek and the Wapsipinnicon formations each include some shale and 
magnesian rock, but in general the Devonian limestones in Iowa are 
characteristically free from magnesia. 
WAPSIPINNICON FORMATION. 
DISTRIBUTION. 
This formation was first discriminated by W. H. Norton, who has 
discussed it in considerable detail and has mapped various subdivisions 
belonging to it in Linn, c Cedar, d and Scott 6 counties. J. A. Udden 
has discriminated it in Muscatine County/ and Calvin has mapped 
certain members belonging to it in Johnson r/ and Buchanan h counties. 
Details of the development of the formation may be learned from the 
reports cited. In the northern portion of the State there is an over- 
lap, so that the Wapsipinnicon is not represented. 
COMPOSITION. 
In general it ma} 7 be stated that, while the formation includes some 
shale and some very pure limestones, the magnesia is apt to be found 
abundant in almost any section, and careful sampling will be necessary 
to determine the availability of the rock at any given point. The 
Fayette breccia, which forms one member of the Wapsipinnicon, 
a Calvin, S., Geology of Johnson County: Iowa Geol. Survey, vol. 7, pp. 33-104. 
b Udden, J. A., Geology of Muscatine County: Idem, vol. 9, pp. 247-388. 
c Geology of Linn County: Iowa Geol. Survey, vol. 4, pp. 121-195. 
d Geology of Cedar County: Idem, vol. 11, pp. 279-396. 
e Geology of Scott County: Idem, vol. 9, pp. 389-520. 
/ Geology of Muscatine County: Idem, vol. 9, pp. 248-388. 
o Geology of Johnson County: Idem, vol. 7, pp. 33-116. 
h Geology of Buchanan County: Idem, vol. 8, pp. 201-255. 
