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A New Rock in Hawaii Is Made of Plastic



The shelf life of plastics may be a lot longer than originally believed. It survives Arctic ice entrapment and having tons of weight on it in landfills. Now, on Hawaii’s shores, plastic is being found in rock form. The components of a new type of rock include sand, seashells, volcanic rock, coral and plastic.

A geologist at London, Canada’s University of Western Ontario, Patricia Corcoran and the captain of Alguita, an oceanographic research ship, Charles Moore, made their discovery on a Big Island beach. They are calling these rocks “plastiglomerates.” In GSA Today this month, they published a report regarding their findings. The two scientists believe that the rocks are formed when humans melt plastic in their campfires.

The scientists do point out, however, that wherever a hot enough heat source is present in the same place as large amounts of plastic waste, the potentiality is there for plastiglomerates to form. Lava flows and forest fires would be ideal. Still hot, melted plastic works as a sort of glue, binding together whatever else is in the vicinity. In the right circumstances, the melted plastic can pour into the crevices and cracks in large rocks.

Corcoran stated that much of the plastic is actually still able to be recognized from its previous purposes. They have found rope, forks and toothbrushes embedded in the pieces of plastiglomerates. The weight of the fused plastic, coral and rock will cause it to sink to the floor of the ocean, which increases the chances of plastiglomerate becoming part of future geologic records.

A team of researchers, including Corcoran, combed Kamilo Beach on Hawaii searching for more samples of the new rocks. Of the 21 sites they visited, all of them had pieces of plastiglomerate. Other beaches in the state have proved to be home to even more of the plastiglomerate rocks. Corcoran said that she fully expects now that the new rock form has been identified, it will be discovered that coastlines all over the world have them as well.

A paleontologist at the University of Leicester in the UK, Jan Zalasiewicz, believes that the ongoing discovery of plastic in unexpected places worldwide warrants an official declaration of a new epoch, the Anthropocene. Humans have left their mark on the planet in a massive variety of pervasive ways. Zalasiewicz points out that this would provide future scientists with a marker denoting the beginning of the time when humans essentially wrapped the Earth in plastic. In fact, since 1950, humans have produced almost 6 billion metric tons of plastic, literally enough to shrink-wrap the planet.

Zalasiewicz claims that because of the abundance of plastic and its ability to persist in the environment, there is an excellent possibility that forms like plastiglomerate will be in the fossil record. They would be future indicators for anthropologists who will cite the samples as part of the Anthropocene Era.

Indeed, it is a bizarre legacy for these times, yet it is the reality. Rocks in Hawaii, and likely elsewhere, are now made of plastic. Perhaps Mr. McGuire, in the 1967 film, The Graduate, was right, “There’s a great future in plastics.” Well, a great future for plastiglomerates.

By Stacy Lamy


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