The geology of Brazil's volcanic island of Trindadea has fascinated scientists for years, but the discovery of rocks made of plastic debris in this remote turtle haven is causing alarm.
Melted plastic is an integral part of the rocks on the island, which is located 1.140 km from the southeastern state of Espirito Santo, and this, scientists say, is evidence of the increasing influence of humans on the Earth's geological cycles.
"It's new and scary at the same time, because contamination has entered the realm of geology," said Fernanda Avelar Santos, a geologist at the Federal University of Paraná.
Santos and her team conducted chemical tests to find out what kind of plastic is in rocks called "plastiglomerates," because they are made of a mixture of sedimentary granules and other debris held together by plastic, reports N1.
"We identified (pollution) mainly from fishing nets, which is a very common waste on the beaches of the island of Trinidad," Santos said.
"Sea currents drag them in and they accumulate on the beach. When the temperature rises, that plastic melts and is incorporated into the natural material of the beach," she added.
The island of Trinidad is one of the world's most important protected areas for green turtles, where thousands come every year to lay their eggs.
The only people on Trindade are members of the Brazilian Navy, which has a base on the island and protects the nesting turtles.
"The place where we found those specimens is a permanently preserved area in Brazil, close to where the turtles lay their eggs," Santos said.
The discovery raises questions about the human legacy on Earth, Santos says.
"We talk so much about the Anthropocene and that's it," Santos said, referring to a proposed geological epoch defined by the impact of humans on the planet's geology and ecosystems.
"Pollution, marine litter and plastics dumped into the oceans become geological material… preserved in the Earth's geological record."