250 
ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY 
[BULL. 168. 
F. Near Fort Worth. 
G. East side of St. Johns River, near Seville. 
H. Corroded surface, Miami Reef. 
I. Near Oak Hill. 
J. Near Melborne. 
Analyses by F. W. Clarke, record No. 885. 
F. 
<;. 
H. 
I. 
J. 
1 
Si0 2 
2.94 
.23 
51. 51 
.71 
41.59 
2.64 
8.50 
.73 
47.29 
1.51 
39. 00 
3.37 
2.99 
.65 
51.22 
.06 
41.22 
2.23 
5.87 
.95 
50. 34 
.37 
39. 62 
3. 21 
17.83 
1.18 
43. 85 
.26 
34. 31 
2.. 53 
ALOo, Fe,0, 
CaO 
MgO 
CO, 
H.,0 
99.62 
100. 40 
98. 37 
100. 36 
99. 96 
K. Coarse shell mass, Senote. 
L. Coral rock, Salt Key Bank. 
M. Loggerhead Key. 
Analyses by L. G. Eakins, record No. 882. The following analyse 
also by Eakins, No. 883, are included for comparison: 
N. Coralline bottom, Barbados. 
O. Recent coral (Siderostria), Bermuda. 
Si0 2 . 
A1A 
FeA 
CaO. 
MgO 
co 2 . 
H 2 0. 
K. 
.22 
.18 
54. 87 
.64 
43. 89 
.11 
99.91 
11 
01 
53. 54 
.71 
43. 87 
1.13 
99.40 
.20 
.22 
53. 54 
.78 
43. 71 
.81 
99.26 
1.17 
.31 
46.45 
5.15 
43.40 
2.73 
99.21 
.23 
trace 
55. 16 
.20 
43.74 
.54 
99.8. 
