76 BULLETIN 61, U. S. DEPARTMENT OF AGRICULTURE. 
Table X. — Composition of rocks of basin region. 1 
Constituent. 
Gran- 
ite 
(av. of 
113 
analy- 
ses). 
Bhvo- 
lite 
(av. of 
103 
analy- 
ses). 
Ande- 
site 
(av. of 
131 
analy- 
ses). 
Dacite 
(av. of 
44 
analy- 
ses). 
Diorite 
(av. of 
85 
analy- 
ses). 
Dia- 
base 
(av. of 
19 
analy- 
ses). 
Basalt 
(av. of 
110 
analy- 
ses). 
Sand- 
stone 
(av. of 
55 
analy- 
ses). 
Lime- 
stone 
(av. of 
29 
analy- 
ses). 
Shales 
(av. of 
16 
analy- 
ses). 
Si0 2 
Per ct. 
66.64 
14.76 
1.62 
1.72 
1.51 
2.74 
3.48 
4.04 
.38 
1.11 
.42 
.03 
.16 
.12 
.04 
.05 
.74 
.03 
.02 
.32 
Tr. 
.07 
Per ct. 
71.55 
13. 90 
1.20 
.94 
.60 
1.56 
3.23 
4.17 
.52 
1.71 
.30 
.03 
.13 
.09 
.03 
.04 
Per ct. 
61.29 
15.16 
2.71 
2.86 
2.99 
4.84 
3.30 
2.93 
.63 
1.42 
.56 
.02 
.26 
.15 
.05 
.09 
.07 
.08 
Per ct. 
65.31 
15.37 
2.45 
1.13 
1.34 
3.35 
3.55 
2.85 
1.18 
2.29 
.53 
.01 
.15 
.09 
.04 
.05 
.02 
.18 
Tr. 
.07 
.04 
(?) 
Per ct. 
58.84 
16.06 
1.97 
3.79 
3.93 
6.27 
3.62 
2.17 
.25 
1.31 
.67 
.01 
.22 
.08 
.03 
.08 
.16 
.03 
Per ct. 
52.04 
15.89 
2.48 
6.84 
5.95 
8.43 
3.20 
.98 
.47 
2.17 
1.06 
.00 
.23 
.16 
.01 
.09 
Per ct. 
51.29 
15.65 
3.10 
5.98 
8.37 
8.78 
2.81 
1.26 
.74 
1.78 
1.01 
.01 
.37 
.08 
.04 
.11 
.08 
.05 
Per ct. 
70.55 
5.80 
1.06 
2.53 
1.16 
5.33 
1.82 
1.32 
2.96 
.39 
Per ct. 
8.82 
.89 
1.01 
3.58 
44.35 
.51 
1.17 
Per ct. 
54.32 
A1 2 3 
14.54 
Fe->0 3 
2.23 
Feb 
2.81 
MgO 
3.18 
CaO 
4.47 
Na^O 
1.65 
KoO 
2.11 
HoO-. 
1.74 
H"0+ 
3.44 
Ti0 2 
.62 
Zr0 2 
P 2 5 
.17 
.13 
.17 
BaO 
.08 
SrO 
: 
MnO 

1.14 
.37 
S 
CI 
:::::::::: 
F 

.56 
Tr. 
.03 
.51 
.49 
6.74 
38.40 
7.93 
LioO 
S0 3 
.17 
.34 
100. 00 
100. 00 
100. 00 
100. 00 
100.00 
100.00 
100. 00 
100. 00 
100.00 
100.00 
1 Compiled from: Vol. I, Fortieth Parallel Survey, Bui. No. 419, U. S. Geol. Survey; Monographs I and 
XI, U.S. Geol. Survey; Bui. No. 491, Data of Geol. Chemistry, U. S. Geol. Survey. 
