ECKEL.] 
MICHIGAN. 
205 
soluble salts. Some of the Coal Measure shales, which are often too gritty, and some 
of the clays derived from the weathering of these shales or the Devonian black shales, 
may be suitable. Surface deposits of clay of any size are, almost without exception, 
either too calcareous and irregular in composition or too gritty to be desirable." 
The difficulty of obtaining a suitable clay to use in connection with the marl 
deposits of the southern portion of the Southern Peninsula has led several of the 
Portland cement companies now in operation in that region to employ clay brought 
from Ohio. The most of this material comes from Milbury and Bryan and is a 
lacustral clay, deposited from the waters of the Erie basin (Glacial Lake Warrvn ) 
when more widely expanded to the southwestward than now. Its composition is as 
follows: 
Analyses of Ohio clays. 
Constituent. 
§ilica(Si0 2 ) 
Alumina ( A1 2 3 ) 
Ferric oxide (Fe 2 3 ) 
Lime(CaO) 
Magnesia (MgO ) 
Sulphuric anhydride (S0 3 ). 
Loss on ignition 
a 62. 55 
61. 03 
17.46 
18.10 
5.08 
6.65 
2.30 
1.29 
1.67 
.53 
Trace. 
1.05 
5. 55 
9.21 
Total 
98.37 
89.86 
a With the silica is included 3.76 per cent of fine sand. 
1. Milbury. Analysis by E. D. Campbell. 
2. Bryan. Analysis by John G. Dean and N. S. Potter, jr. 
REFERENCES ON MICHIGAN CEMENT RESOURCES AND 
INDUSTRY. 
avis, C. A. A contribution to the natural history of marl. Mich. Geol. Survey, 
vol. 8, pt, 3, pp. 65-102. 1904. 
all, Delos. Marls and clays in Michigan. Mich. Geol. Survey, vol. 8, pt. 3, 
pp. 343-348. 
3ale, D. J. Marl and its application to the manufacture of Portland cement. 
Mich. Geol. Survey, vol. 8, pt. 3, pp. 1-64, 103-190. 
Kimball, L. L. Portland cement in Michigan, 1903. Min. Resources U. S., for 1903, 
U. S. Geol. Survey, 1904, pp. 903-910. 
jane, A. C. Coal of Michigan; its mode of occurrence and quality. Mich. Geol. 
Survey, vol. 8, pt. 2, pp. 1-233. 1902. 
ane, A. C. Notes on the origin of Michigan bog limes. Mich. Geol. Survey, 
vol. 8, pt. 3, pp. 199-223. 
ane, A. C. List of marl localities and Portland-cement mills in Michigan. Mich. 
Geol. Survey, vol. 8, pt. 3, pp. 224-342. 
athbury, B. B. The development of marl and clay properties for the manufacture 
of Portland cement. . Mich. Geol. Survey, vol. 8, pt. 3, pp. 191-198. 1903. 
jAthbury, B. B. The Michigan Alkali Company's plant for manufacturing Port- 
land cement from caustic soda waste. Engineering News, June 7, 1900. 
ewis, F. H. The plant of the Michigan Portland Cement Company, Coldwater, 
Mich. Engineering Record, Feb. 25, 1899. 
