14 
SANTA MARIA OIL DISTRICT, CALIFORNIA. 
stone was composed largely of Pliocene shells, as determined by 
Doctor Dali. Eldridge remarks: u In view of the supposed age of 
the serpentine, it is thought that the deposit was formed by the 
accumulation of sediment and shells in a crevice of the older rocks 
at the time they perhaps formed the sea bluffs.” 
The same writer published a brief summary of his knowledge con¬ 
cerning the Santa Maria district in 1903.® 
The San Luis folio, 6 by II. W. Fairbanks, issued in 1904, contains 
much that relates to the district in general, although it pertains 
directly only to the part containing the Arroyo Grande field. It 
is the most comprehensive report concerning the northwestern 
part of the Santa Maria district yet published. 
The present writers have published two papers concerning the 
geology and economic resources of the Santa Maria district. The 
first is entitled “ Diatomaceous deposits of northern Santa Barbara 
County, Cal.,” c and the second 11 Preliminary report on the Santa 
Maria oil district, Santa Barbara County, Cal.” d A third paper 
treating more in detail the burning of the shale is “ Metamorphism 
by combustion of the hydrocarbons in the oil-bearing shale of 
California/’ to be published in the Journal of Geology. 
EARLY HISTORY OF THE DISTRICT. 
The Santa Maria district was up to 1899 entirely unknown as an 
oil-producing territory. To Messrs. McKay and Mulholland, of Los 
Angeles, is due the credit for starting operations in the Santa Maria 
field proper. After a favorable report had been made by Mr. 
Mulholland on certain lands of the Careaga ranch, the Western Union 
Oil Company was organized, drilled three prospect holes, and was 
finally rewarded in August, 1901, by striking paying quantities of 
oil in the third well. In 1902 the Pinal Oil Company, of Santa Maria, 
began operations on the north side of Graciosa Ridge, and meeting 
with marked success was followed by the many other companies 
that have since undertaken operations in this field. 
Successful wells were drilled in the Lompoc field in 1904, and since 
that time the further development of this part of the district has 
been assured. A later field to attract attention is that adjacent 
to the town of Arroyo Grande, where development is well under way, 
being stimulated by the completion of the successful Tiber well 
No. 1 late in 1905. Prospecting is now (January, 1907) going 
forward in the Huasna field east of the Arroyo Grande field, and the 
operators there confidently expect to develop productive wells. 
a Contributions to economic geology, 1902: Bull. U. S. Geol. Survey No. 213,1903, p. 313. 
b Geologic Atlas U. S., folio 101, U. S. Geol. Survey. 1904. 
c Bull. U. S. Geol Survey No. 315, 1907, pp. 438-447. 
dBull.U. S. Geol. Survey No. 317, 1907, pp. 1-09, 2 pis., l fig. 
