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SANTA MARIA OIL DISTRICT, CALIFORNIA. 
being 1 per cent is too liberal, it would seem that the low estimates 
of the amount of diatomaceous material present and the complete 
ignoring of the other important organic sources for oil in the shale, 
would still cause the estimate to be conservative. 
In considering the question, What kind of organic material has a 
character most favorable for producing oil ? the relative rate of putre¬ 
faction is important. Plants have the advantage in respect to their 
slower rate of decomposition. David White inclines to the view that 
plants are more favorable to the production of oil, largely for this 
reason. He. says that putrefaction, which is largely a bacterial 
process, goes on more rapidly in animal tissue, while vegetable mate¬ 
rial has a tendency to turn into hydrocarbons. The slow decompo¬ 
sition of the protoplasm contents of the diatom frustule is especially 
significant. F. J. Keeley, of the Philadelphia Academy of Natural 
Sciences, says as follows in a letter: 
The only point I can think of that might have any bearing on the question of the 
relation of diatoms to petroleum is the fact that the organic matter of diatoms does not 
appear to decompose and become dissipated quickly after death, as is the case with 
most low organisms. It is well known that diatoms kept in water will show the 
shrunken contents for years, and Elirenberg noted the presence of such organic con¬ 
tents in old fossil diatoms from Hanover, while J. Brun reports a similar observation 
in a fossil deposit from Holland. 
It is worthy of note that many of the round white diatom tests of 
the soft Monterey shale contain minute specks of black that appear 
like bituminous material derived in situ from the diatom. These 
specks, however, are present in but a small proportion of the tests 
and there is no proof that the black substance has not come from 
infiltration and deposition in the slight hollow of the shell. Thin 
sections of the shale reveal small black filaments that appear to be 
carbonaceous material. 
It is probable that the ooze at the sea bottom in Monterey time 
was being deposited very rapidly. The idea of rapid accumulation 
of the deposits of diatoms, aided by the accession of organic and 
detrital material of other kinds, is quite in keeping with the well- 
known faculty of these organisms for quick and abundant reproduc¬ 
tion; and it is not only in keeping with but an essential corollary of 
the fact that deposits of such vast thickness were formed during 
middle Miocene time. This rapid accumulation created further 
favorable conditions for the production of oil, inasmuch as the organic 
substance that reached the sea floor became quickly buried without 
sufficient time intervening for decomposition to go very far. Thus 
the contents of the diatom frustules and all the other plant and 
animal remains became included in the body of the deposit. 
The alkalinity of the shale may have been another favoring factor. 
As the deposits grew, salts of the sea water were probably included 
