Ancient California Islanders Relied on Drifting ‘Tarballs’ for Petroleum, Study Finds

Bitumen that comes from underwater seeps can sometimes form “tar whips,” like this one found near Point Conception. (USGS)

... Archaeologist Kaitlin Brown of the University of California, Santa Barbara, led a study of the bitumen found on Channel Island artifacts dating back as much as 7,700 years, and found that the petroleum originated from an underwater seep more than 40 kilometers away.

“There has been much debate about the use of asphaltum from submarine sources in California,” Brown said in an interview.

“Ethnographic accounts state that terrestrial asphaltum was the only ‘high-grade’ source available for canoe construction.  Many archaeologists believe that even the trade of asphaltum to the Channel Islands led to an increase in social complexity.”

But if the trade of this high-quality petroleum was part of what tied the region’s native groups together, she explained, evidence that islanders used their own supplies may suggest that they enjoyed a sort of ancient economic independence.

“In our article, we find that native islanders would use asphaltum from locally available sources and did not need to rely on mainland asphaltum exchange for their everyday needs,” she said.

Brown and her colleagues report their findings in the Journal of Archaeological Science.

The team sampled bitumen found at six sites on two of the Channel Islands: One, dated to about 7,700 years old, was part of a fishing kit discovered in a rockshelter on San Miguel Island.

Two more were taken from a site on San Nicolas Island, where artifacts about 4,000 years old included rocks and abalone shells that were used for applying asphaltum. [...] westerndigs.org/

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