I eckel.] NORTH DAKOTA, OHIO. 269 
PORTLAND-CEMENT RESOURCES OF NORTH DAKOTA. 
Only one limestone formation of any importance — the Niobrara chalk, 
[of Cretaceous age — is found in North Dakota, and even this is almost 
(entirely concealed by a thick covering of drift. The Niobrara chalk 
lis the formation which is now utilized for Portland-cement manufac- 
jture at Yankton, S. Dak., while it gives promise of being a future 
(source of cement material in Nebraska and Iowa. 
The physical characters and chemical composition of the Niobrara 
Hchalk throughout various portions of its range are fully described in 
(the text relating to deposits in the States above mentioned, and analy- 
ses will be found on pages 148 and 301. It is of peculiar value as a 
jPortland-cement material, both because of its softness, which permits 
;it to be easily crushed and pulverized, and because of its usual freedom 
prom magnesia and other injurious ingredients. Outcrops of the Nio- 
brara chalk, moreover, are commonly capped by clays of the Pierre 
group, which furnish admirable materials for mixing with the chalk. 
Portland cement manufacture has been attempted at only one point 
in North Dakota, and here the Niobrara chalk was found to be too low 
in lime to be used for this purpose. Analyses of the materials at this 
point will be found in the section on natural cement, page 352. 
PORTLAND-CEMENT RESOURCES OF OHIO. 
PORTLAND-CEMENT MATERIALS. 
The geologic groups which contain low-magnesia limestones in Ohio 
are the following: 
(1) Trenton limestone. 
(2) Cincinnati series of limestones and shales. 
(3) Clinton limestone. 
(4) Oorniferous (Devonian) limestone. 
(5) Maxville (Mississippian) limestone. 
(6) Ferriferous and other Coal Measure (Pennsylvania) limestones. 
(7) Quaternary marls. 
The distribution throughout the State of the first six of these lime- 
stone groups is shown on the map, PI. XII. 
TRENTON SERIES, a 
This series consists of shale and pure limestone. It outcrops as a 
narrow strip along the Ohio River from the mouth of the Little Miami 
to a point a mile or two above New Richmond. This is the formation 
that the Mentor plant on the south side of the Ohio River has been 
planned to use. 
In view of the cheapness of fuel and transportation, the abundance 
and its general excellence of material, and the ease with which it may 
be procured, the strips bordering the Ohio River from Madison, Ind., 
to Maysville, Ky., seem to offer unusually promising locations for 
Portland cement plants. 
a Most of the notes on the Trenton and Cincinnati limestones were contributed by Mr. E. O. Ulrich 
of the U. S. Geol. Survey. 
