Rocks Formed From Plastic Found On Beach

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Lisa Winter

Guest Author

1133 Rocks Formed From Plastic Found On Beach
Patricia Corcoran

Every single piece of synthetic plastic that has ever been manufactured since 1950 is still in existence today, as each one takes thousands of years to break down. A recent study has indicated that plastic litter can become fused with rocks and other materials to form a new material: plastiglomerate. This material could very well become a permanent part of the geological record, forever marking humanity’s impact on the world. The results of the report were published in the journal of the Geological Society of America, GSA Today.

The material has been discovered before, but it wasn’t until it had washed up on Hawaii’s Kamilo Beach, notorious for its litter, that it was studied and identified. The discovery of the Hawaii sample was made by Captain Charles Moore of the research vessel of Alguita as well as lead author Patricia Corcoran. It is believed that human campfires melted plastic on the beach, causing it to fuse to shells, coral, and sand. 




The researchers searched 21 additional sites, finding plastiglomerate at all of them. It is believed that it likely exists throughout the world, likely largely unnoticed. Though burning garbage is largely frowned upon due to the amount of pollutants its generates, it does happen around the world, and is probably generating plastiglomerate in the process.

When plastiglomerate gets pulled off the beach into the ocean, its density causes it to sink to the bottom. It then has a much better chance of getting buried in the sediment and becoming a permanent part of the fossil record; forever indicating humanity’s presence in the world. On its own, plastic’s density isn’t great enough for it to become buried and possibly fossilized. 


Millions of years from now, whatever the predominant intelligent species is on Earth could look at that aspect of the fossil record to mark the beginning of the Anthropocene, a proposed geological epoch to mark the beginning of humanity’s dominance and impact on the planet. 



There are two proposed types of plastiglomerate: clastic and in situ. Clastic is a loose conglomeration of natural material held together by plastic “glue” that melted and then cooled. In situ plastiglomerate is less common and is formed when plastic melts and fuses directly to a rock.


However, not everyone believes that our distant descendants will look back on us in shame (well, at least for this), because when rocks get pulled deeper into the Earth due to tectonic processes that would expose the plastiglomerate to intense temperatures and pressure that would revert it to a crude oil-like state. The authors of the study defend their position by saying that won’t work for all types of plastic.

Since 1950, there has been about 6 billion metric tons of plastic produced. It has been found in some fairly devastating locations, including the deepest parts of the ocean and in wildlife (both inside and out). Plastic has been an amazing resource for humans, but we need to be more responsible. Out of the estimated 1 trillion plastic shopping bags used each year around the globe, about 10% will end up in the oceans. The United States alone utilizes 50 billion plastic water bottles each year, and less than 15% of those will be recycled. If you’d like more tips and information about sustainable living to better our historical reputation, check out the IFLS article “Celebrate Earth Day Everyday.”


  • tag
  • plastiglomerate,

  • plastic,

  • anthropocene