ECKEL.] IOWA. 163 
Analysis of Dekalb limestone. 
Lime carbonate (CaC0 3 ) 91. 96 
Magnesium carbonate (MgC0 3 ) 1 . 99 
Water (H 2 0) - 07 
ECONOMIC CONDITIONS. 
AVAILABLE MATERIALS. 
It is believed that the data presented bear out the assertion that 
there are man}^ points in Iowa at which materials suitable for manu- 
facture are available. The marls are not now known to be important 
and may never prove to be. Chalk suitable in all particulars may be 
found along Sioux River north of Sioux City. As this is a soft, easy- 
grinding material, it is a favorite among cement manufacturers. The 
question of the advisability of establishing a plant in this district must 
be determined by consideration of manufacturing costs, of market, 
nd transportation facilities. 
In regard to the limestones the following general considerations arc 
important. Iowa is largely a drift-covered State, and within the broad 
ireas shown upon the map as underlain by the various limestones there 
ire really only a limited number of outcrops. Even where outcrops 
>ccur the overburden is in many cases so thick as to entail prohibitive 
stripping costs. The best situations are in the valleys, usually where 
some important tributary joins the main stream. Fortunately many 
)f the railway lines follow valley routes. 
The Trenton limestone, which occurs in the driftless area, is found 
isually in rather steep bluffs, a fact due to the resistant character of 
he dolomite usually found above it. As compared with the other 
imestones of the region, the Trenton is most likely to carry magnesia 
n excess; but it is, on the other hand, practically free from chert, is 
)ften somewhat carth}^ in composition, and is intimately associated with 
shale. As already noted, the similar and approximately equivalent 
)eds in the Lehigh district of Pennsylvania and New Jersey are a very 
mportant source of cement material. 
The Devonian limestones are. in large measure free from both chert 
nd magnesia, though outcrops in the northern part of the State need 
areful examination to make sure of the absence of the latter. As 
ontrasted with both the Trenton and the Carboniferous limestones 
hey are in the main harder, and this will to some extent influence the 
ost of grinding. 
Of the Carboniferous limestones the Kinderhook is in most situa- 
ions too magnesian and the Osage too full of chert for easy use, 
hough it is probable that some suitable material can be found in each 
: ormation. The Pella beds of the St. Louis and the Winterset and 
ther limestones of the Missourian are entirely suitable as regards 
