296 
ANALYSES OF ROCKS, IT. S. GEOLOGICAL SURVEY. 
[BULL. lf>8. 
ILLINOIS, IOWA, MINNESOTA. 
A, B. Clays from Henry County, Illinois. Analyses by T. M. 
Chatard, record No. 144. 
C. Loess, a stratum overlying residuary clay, 350 feet above the 
Mississippi River, near Galena, Illinois. Described by Chamber] in 
and Salisbury, 6th Ann., p. 282. Analysis by R. B. Riggs, record 
No. 293. Dried at 100°. 
D. Loess, 300 feet above the Mississippi, 3i miles northwest of 
Dubuque, Iowa. Described by Chamberlin and Salisbury (I. <?.), and 
analyzed by Riggs, No. 292. Dried at 100°. 
E. Tallow clay, lead mine at Lansing, Iowa. Collected by W. P. 
Jenney. Analysis by H. N. Stokes, record No. 1337. Dried at 100°. 
Partial analysis. 
F. Greenish-gray clay, New Ulm, Minnesota. Analysis by T. M. 
Chatard, record No. 825. 
A. 
B. 
c. 
D. 
E. 
F. 
Si0 2 
46.12 
15. 24 
4.41 
42. 58 
12.16 
3.90 
64.61 
10.64 
2.61 
.51 
3. 69 
5.41 
1.35 
2.06 
2.05 
.40 
.06 
.05 
72.68 
12. 03 
3. 53 
.96 
1.11 
1.59 
1.68 
2.13 
2.50 
.72 
.23 
.06 
52.08 
23. 11 
9.34 
61.32 
12.27 
3.62 
4.18 
1.76 
.99 
42 
3.59 
10.73 
.66 
.27 
.27 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 
Ti0 2 
PA 
MnO 
ZnO 
3.63 
8.63 
1.54 
3.79 
15. 57 
.79 
.08 
.28 
4.32 
11.33 
1.96 
3.88 
18.64 
.64 
.10 
.09 
2.12 
1.04 
unde!.. 
undet. 
9.80 
trace 
trace 
PbO 
BaO 
.05 
C0 2 
6.31 
.13 
.11 
.07 
.39 
.09 
.51 
.01 
C, organic . . 
S0 3 
.19 
CI 
100. 08 
99.60 
100. 06 
100. 22 
97.49 
100. 32 
