Plastic Lava Rocks

“plastiglomerates”

Plastics only started appearing in the 1950s, with production and disposal rates increasing steadily over the last 60 years. With crazy low recovery rates, plastic debris is accumulating in our waterways and along shorelines in massive quantities.

Researchers working in Kamilo Beach on the southeastern tip of the Big Island of Hawaii report a new stone formed through the intermingling of melted plastic, beach sand, basaltic lava fragments, and organic debris like seashells.

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.

In the distant future, they’ll be able to date rocks from our time on earth by using the plastic that’s preserved in the sediment record.

They divided plastiglomerate into two types: in situ and clastic. When plastic melts, it can flow into larger rocks and adhere to outcrops — that’s in situ. The clastic type (pictured above) cements a combination of basalt, coral, shells, and local woody debris with grains of sand in a plastic matrix. In some cases, the researchers were able to identify distinct types of molten plastic: netting and ropes, packaging, lids, tubes and pipes, and confetti (colorful, brittle remains of products like food and drink containers).

https://www.sciencemag.org/news/2014/06/rocks-made-plastic-found-hawaiian-beachplastiglomerates

https://www.zdnet.com/article/researchers-discover-rocks-made-of-plastic/