Plastic Rocks Are Starting To Appear On Hawaiian Shores

Scientists say a bizarre new type of geological structure is starting to form on the beaches of Hawaii — one that can only be described as a kind of "plastic rock."

We can now add this to the ever-growing list of strange things happening to our plastic waste, including the rise of the life-friendly plastisphere, and plastics trapped in Arctic ice and on the sea floor.

It's called a plastiglomerate, a new type of rock comprised of plastic, volcanic rock, beach sand, seashells, and corals. According to researchers from Western University in London, Canada, they're most likely forming from melting plastic in fires lit by humans who were camping or fishing, but they can form anywhere where there's a heat source, such as forest fires or lava flows, and "abundant plastic debris."

Writing in Science AAAS, Angus Chen explains more:

When the plastic melts, it cements rock fragments, sand, and shell debris together, or the plastic can flow into larger rocks and fill in cracks and bubbles to form a kind of junkyard Frankenstein.

[Patricia] Corcoran says some of the plastic is still recognizable as toothbrushes, forks, ropes, and just "anything you can think of." Once the plastic has fused to denser materials, like rock and coral, it sinks to the sea floor, and the chances it will become buried and preserved in the geologic record increase.

Corcoran and her team canvassed Kamilo Beach on the Big Island for more of the rocks and found plastiglomerate in all 21 sites they surveyed. She says people have already found plastiglomerate on another Hawaiian island, and she expects there to be much more on coastlines across the world. Plastiglomerate is likely well distributed, it's just never been noticed before now, she says.

The researchers don't believe the plastiglomerate will last forever, adding that the plastics might actually "revert back to a source of oil from whence they came, given the right conditions of burial."

Read Chen's entire report.

Image: Patricia Corcoran.