Researchers working along Maharashtra’s Diveagar beach in the Raigad district have reported an unusual discovery of a plastic–rock combination, marking what they describe as early evidence of a “plastistone” formation on India’s western coast.
During fieldwork in May 2024, scientists collected rock samples from coastal outcrops where plastic debris had become trapped. One sample revealed a green nylon-like filament embedded within the rock structure. Laboratory analysis later confirmed that the material was polyamide, commonly used in fishing nets, suggesting the plastic likely originated from discarded or abandoned fishing gear.
The study, published in Discover Oceans, indicates that this material is not simply surface contamination. Instead, it appears to be integrating with natural sediments and biological matter, forming a new type of geological structure. Researchers say this differs from previously known plastiglomerates, which are typically formed through burning plastic. In contrast, plastistone seems to develop through natural coastal processes such as wave action, ultraviolet exposure, and temperature variations, allowing plastics, sediments, and marine organisms to gradually bind together.
Scientists used microscopic and spectroscopic techniques to examine the samples collected along a 10-kilometre stretch of shoreline. The analysis identified multiple polymer types including polyethylene, polypropylene, PET, and polyamide. The presence of shells, barnacles, and microorganisms such as foraminifera further confirmed that biological materials were also becoming part of the structure.
According to researchers from IISER Kolkata, this interaction between plastic waste, biological matter, and sediments suggests an ongoing process of lithification—where loose materials slowly transform into rock. They describe it as evidence that plastic pollution is now becoming part of long-term geological systems.
Experts also highlighted concerns linked to abandoned fishing equipment, often called ghost gear, which is a major contributor to marine plastic waste globally. These materials, made from durable synthetic polymers, can persist in marine environments for decades while gradually breaking down into microplastics that enter the food chain.
Scientists warn that such plastic–rock formations may store microplastics and release toxins over time, potentially affecting surrounding ecosystems. There is also concern that these materials could alter the physical properties of coastal rocks, including heat retention, which may influence marine species that depend on stable beach temperatures for breeding.
Researchers involved in the study say the discovery highlights the urgent need for improved coastal waste management and monitoring. They are also engaging with local communities and authorities to report similar findings and better understand how widespread these formations may be.
Further studies are planned along India’s coastline and possibly inland water bodies, as scientists believe similar plastic–sediment interactions may become more common in heavily polluted environments.