Plastiglomerate forming a marker horizon in sediment layers

Plastiglomerate is a rock made of a mixture of

sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...

grains, and other natural

debris Debris (, ) is rubble, wreckage, ruins, litter and discarded waste, garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can ref ...

(e.g. shells, wood) that is held together by

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

. It has been considered a potential marker of the

Anthropocene ''Anthropocene'' is a term that has been used to refer to the period of time during which human impact on the environment, humanity has become a planetary force of change. It appears in scientific and social discourse, especially with respect to ...

, an informal epoch of the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

proposed by some social scientists, environmentalists, and geologists.

Origin

Plastiglomerates form along

shoreline A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

s where natural sedimentary grains and organic debris are agglutinated by melted plastic. They can be created during

campfire A campfire is a fire at a campsite that provides light and warmth, and heat for cooking. It can also serve as a beacon, and an insect and predator deterrent. Established campgrounds often provide a stone or steel fire ring for safety. Campfires ...

burning, as has been reported from Kamilo Beach on the island of Hawaii, or during hot weather, as is the case on

Trindade Island Trindade and Martim Vaz (, ) is an archipelago located in the South Atlantic Ocean about east off the coast of the Brazilian state of Espírito Santo, of which it forms a part. The archipelago has a total area of and a navy-supported research ...

Depositional environment

Plastiglomerate could potentially form a marker horizon of human

pollution Pollution is the introduction of contaminants into the natural environment that cause harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...

on the geologic record. and may survive as future

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s. Plastiglomerate may also conceivably form in plastic-polluted regions affected by

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

s or

forest fire A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a bushfire ( in Australia), dese ...

s. They have been found on the surface as well as beneath the sand. This suggests that plastiglomerates are being actively deposited into the sedimentary record. Some geophysicists and geologists speculate that plastiglomerates will not persist in the

fossil record A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

, however, or that they might " to a source of oil from whence they came, given the right conditions of burial". "In situ" plastiglomerate forms where plastic melts and fills in rock cavities. "Clastic" plastiglomerate are smaller solitary pieces that form where larger fused items become fragmented by waves. Plastiglomerate is denser than particles that are solely composed of plastic, which gives them greater potential to become buried and preserved in the rock record. Plastiglomerate Museon

Plastiglomerates have been featured at the Yale

Peabody Museum of Natural History The Peabody Museum of Natural History at Yale University (also known as the Yale Peabody Museum of Natural History or the Yale Peabody Museum) is one of the oldest, largest, and most prolific university natural history museums in the world. It ...

; Oakville Galleries in Oakville, Ontario, Canada; Louis B. James Gallery in New York City; Carleton University Gallery in Ottawa, Ontario, Canada; Prosjektrom Normanns, Stavanger, Norway; and

Museon Museon is a museum for science and culture in The Hague, Netherlands, with a strong focus on education. It regularly presents exhibitions on a range of topics related to the environment, geography or cultural identity. It has an extensive collecti ...

in The Hague, Netherlands. Museon claims to have probably the largest piece of plastiglomerate, which is more than 1m long and 50cm wide.

History

Charles Moore, a sea captain and oceanographer for the Algalita Marine Research Institute in

Long Beach, California Long Beach is a coastal city in southeastern Los Angeles County, California, United States. It is the list of United States cities by population, 44th-most populous city in the United States, with a population of 451,307 as of 2022. A charter ci ...

, discovered this substance in 2006 while surveying Kamilo Beach on the Big Island of

Hawai’i Hawaii ( ; ) is an island state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two non-contiguous U.S. states (along with Alaska), it is the only state not on the North American mainland, th ...

. Geology professor, Dr. Patricia Corcoran and Visual artist professor, Kelly Jazvac of the

University of Western Ontario The University of Western Ontario (UWO; branded as Western University) is a Public university, public research university in London, Ontario, Canada. The main campus is located on of land, surrounded by residential neighbourhoods and the Thame ...

investigated the samples on Kamilo Beach in 2012 where they also coined the term "plastiglomerate". Approximately one-fifth of the plastiglomerates found at Kamilo Beach of fishing debris, one quarter of broken lid containers, and one half consisted of plastic "confetti". The plastiglomerate at Kamilo Beach was more likely created from human

s than from molten lava flows. In 2023, it was reported

plastistone Plastistone is the umbrella term for rocks that have fused with plastic. At the end of 2023 there were numerous sightings of green-colored plastic seemingly melted to rocks. It forms from plastic that floats through the ocean and melts to the ro ...

had been discovered on remote

, a known refuge for turtles.

Origin

Depositional environment

History

See also

References

Further reading