Plastic Legacy: Humankind’s Trash Is Now a New Rock

Jun 6, 2014

By Joseph Castro


Melted plastic trash on beaches can sometimes mix with sediment, basaltic lava fragments and organic debris (such as shells) to produce a new type of rock material, new research shows.

The new material, dubbed plastiglomerate, will forever remain in Earth’s rock record, and in the future may serve as a geological marker for humankind’s impact on the planet, researchers say.

Plastic pollution is a worldwide problem affecting every waterway, sea and ocean in the world, according to the Natural Resources Defense Council. First produced in the 1950s, plastic doesn’t break down easily and is estimated to persist in the environment for hundreds to thousands of years. Plastic debris is also lightweight, allowing it to avoid being buried and becoming a part of the permanent geological record.

But while at Hawaii’s Kamilo Beach, Capt. Charles Moore, an oceanographer with the Algalita Marine Research Institute in California, found that plastic, if melted, can actually become one with rocks, sediment and other geologic materials.

“He found some plastic had been melted to rocks, and other pieces of natural material had also been stuck on it,” said study lead author Patricia Corcoran, a geologist at the University of Western Ontario (UWO) in Canada. “He didn’t know what to call it. It’s possible other people have found [the plastic conglomerates] at other locations before Captain Moore did, but nobody had thought to report it or identify it.”

Corcoran attended a presentation Moore gave about his find, and she became immediately interested in investigating the material. So she, along with Moore and Kelly Jazvac, a visual artist at UWO, headed to Kamilo Beach to analyze the plastic formations.

A human origin

Kamilo Beach, located on the southeastern tip of the Big Island of Hawaii, is often considered to be one of the dirtiest beaches in the world. Because of the current flow and high wave energy of the area, the beach is covered with plastic debris pulled in from the ocean, including fishing gear, food and drink containers and multicolored plastic fragments called “plastic confetti.”

The researchers discovered there are two types of plastiglomerates at Kamilo Beach: In situ and clastic.

In situ plastiglomerate is more rare than the clastic variety, and forms when “plastic melts on rock and becomes incorporated into the rock outcrop,” Corcoran told Live Science, adding that the melted plastic can also get into the rock vesicles, or cavities. Clastic plastiglomerates, on the other hand, are loose rocky structures, composed of a combination of basalt, coral, shells, woody debris and sand that have been glued together by melted plastic.

When Moore first discovered Kamilo Beach’s plastiglomerates, he hypothesized that molten lava had melted the plastic to create the new rock. However, the researchers found that lava had not flowed in that area since before plastics were first invented.

8 comments on “Plastic Legacy: Humankind’s Trash Is Now a New Rock

  • Gives a whole new meaning to ‘beach combing’. Can you hear the ocean in a plastiglomerate?

    plastic legacy…that’s not a legacy we really want

    An unholy alliance it was, man’s plastic + campfires, from the distant past.

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  • 2
    Light Wave says:

    Its really quite annoying and kind of isolationist to prevent commenters from liking other posts….why take that button away RDFSR it was useful….Please put it back……

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  • good point, and while they should put it back they should also explain the science behind how it disappeared, if only to assume god did it! ha just kidding……… you god lovers

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  • My first thought reading this was “George Carlin was right!” In hi “he planet is fine. The people are fucked.” he said:

    The planet will be here for a long, long, LONG time after we’re gone, and it will heal itself, it will cleanse itself, ’cause that’s what it
    does. It’s a self-correcting system. The air and the water will
    recover, the earth will be renewed, and if it’s true that plastic is
    not degradable, well, the planet will simply incorporate plastic into
    a new pardigm: the earth plus plastic.

    An here is is the new paradigm. I bet he would have loved that ^^

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  • 6
    Promethean Entity says:

    Maybe looking for this ‘plastiglomerate’ rock on other planets could be incorporated into SETI and other investigations looking for evidence of ET intelligence.

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