GEOLOGY. 
45 
Analyses of Monterey shale. 
Diatomaceous shale. 
Flinty shale. 
Lime¬ 
stone. 
1 . 
2 . 
3. 
4. 
5. 
6 . 
7. 
8 . 
9. 
10 . 
11 . 
Si0 2 . 
65.62 
72.50 
11.71 
2.35 
.32 
.83 
1.88 
9.54 
83.19 
80.59 
86.89 
2.32 
1.28 
1.43 
Trace. 
3.58 
4.89 
92.88 
86.92 
4. 27 
92.37 
2. 46 
97.02 
98.1 
Not 
det. 
Not 
det. 
AI 2 O 3 . 
Fe 2 03 (total iron)_ 
CaO. 
1.60 
Trace. 
2. 48 
5.13 
1.70 
27.86 
16.64 
MgO. 
Alkalies (Na 2 0,K 2 0). 
Ignition. 
11.00 
2. 74+ 
C0 2 
99.13 
100.39 
100. 40 
99.27 
1. Soft, white diatomaceous shale; Purisima Hills, 3J miles southwest of Harris, Santa Barbara 
County, Cal. Analyst, W. T. Schaller, 1907. 
2. Soft, white diatomaceous shale; Graciosa Ridge, 3 miles southeast of Orcutt, Santa Barbara 
County, Cal. Analyst, W. T. Schaller, 1907. Approximate analysis. 
3. Soft, white diatomaceous shale; San Julian ranch, at junction of El Jaro and Salsipucdes creeks, 
Santa Barbara County, Cal. Analyst, E. C. Sullivan, 1907. 
4. Soft, white diatomaceous shale; San Antonio terrace, 2 miles south of Casmalia, Santa Barbara 
County, Cal. Analyst, E. C. Sullivan, 1907. 
5. White shale; Monterey, Monterey County, Cal. Lawson, A. C., and Posada, J. de la C., Bull. 
Dept. Geology, Univ. California, vol. 1, 1893, p. 25. Specific gravity, 1.8-2.1. 
6 . Gray, glassy porcelain shale; from same hand specimen as No. 4. Analyst, E. C. Sullivan, 1907. 
7. White porcelain shale; region of Point Sal, Santa Barbara County, Cal. Analyst, II. W. Fair¬ 
banks, Bull. Dept. Geology, Univ. California, vol. 2, No. 1, 1896, p. 12. 
8 . Opaque flint; Point Sal, Santa Barbara County, Cal. Analyst, H. W. Fairbanks, loc. cit. 
9. Hard, black, clear flint; 1J miles west of Zaca, Santa Barbara County, Cal. Analyst, E. C. Sulli¬ 
van, 1907. 
10. Hard, black, clear flint; Point Sal, Santa Barbara County, Cal. Analyst, II. W. Fairbanks, loc. 
cit. 
11. Bituminous limestone; Redrock Mountain, northeast of Lompoc, Santa Barbara County, Cal. 
Analyst, George Steiger, 1907. 
ALTERATION. 
The differences in character and composition between the soft and 
hard varieties of the Monterey shale have been brought out in the 
foregoing discussion. The question arises, To what are these differ¬ 
ences due? It is difficult to give a decisive answer. The main differ¬ 
ences in the gradations from the soft to the hard shales lie in the 
siliceousness, compactness, hardness, and degree of crystallization. 
Taken as a whole the lower division is made up largely of hard shale 
and the upper of soft shale, but gradations from one variety to 
another within an extremely small space occur in both divisions. 
In some places a thick series of beds of similar character is marked 
off from a series of different character. Elsewhere a variation occurs 
bed by bed, or, in still other places, a single bed or lens of shale of 
one variety is included within another kind. The softer varieties 
contain at many points small lenses of hard, brittle, or semiflinty 
shale elongated parallel with the bedding, or strata in which lenses 
are strung along at irregular intervals, or single small beds com¬ 
posed entirely of harder material. In such occurrences there seems 
to be a gradation from one variety to the other, and the outlines 
of the hard layers are not regular or very definite. For example, 
the diatom-bearing shale of chemical analysis No. 4 and the glassy 
1784—Bull—322—07-4 
