Histories of California contain many descriptions of extensive oil seepage both on shore and off. Here’s an example from further up the coast, from a book published in 1883:
“The flowing springs of petroleum early attracted the attention of the settlers. The oil was flowing from the earth in hundreds of places, sometimes forming large pools into which cattle, sheep, and horses, as well as wild animals, would venture and get caught, leaving their bones as a warning of danger for future visitors. Sometimes it flowed into the streams and would float away for miles before it evaporated. There were hundreds of acres, perhaps thousands, covered with the residuum left after the evaporation of the lighter parts. Springs of it also occur in the Santa Barbara Channel, and the first navigators had fears of the near vicinity of a hot place, from the villainous smell that pervaded the atmosphere where the oil was floating on the ocean.”
History of Santa Barbara County, California, with Illustrations and Biographical Sketches of Its Prominent Men and Pioneers
https://archive.org/details/historyofsantaba00maso/page/n189...