Technofossils' Humanity's geo-legacy will be plastic bags and chicken bones

As an eternal testament to humanity, plastic bags, cheap clothes and chicken bones are not much of a legacy. But two geologists exploring which items from our technological civilisation are most likely to survive for many millions of years as fossils have reached an ironic but instructive conclusion: fast food and fast fashion will be our everlasting geological signature.

- Damian Carrington

"Plastic will definitely be a signature 'technofossil', because they're incredibly durable, we are making massive amounts of it, and it gets around the entire globe," says Prof Sarah Gabbott, a University of Leicester expert on the formation of fossils. "So wherever those future civilisations dig, they are going to find plastic. There will be a plastic signal that will wrap around the globe."

Fast food containers dominate ocean plastic but aluminium drink cans will also be part of our legacy. Pure metals are exceptionally rare in the geological record because they readily react to form new minerals, but the cans will leave a distinct impression.

"They're going to be around in the strata for a long time and eventually you would expect little gardens of clay minerals growing in the space where the can was. It's going to be a distinctive, new kind of fossil," says Prof Jan Zalasiewicz, a leading proponent of the Anthropocene as a new geological epoch dominated by humans. Zalasiewicz has written a book with Gabbott about technofossils called Discarded.

Another fast food staple, chicken, is also destined for immortality. Bones are well known as fossils, but while the bones of modern broiler chickens are fragile - they have been bred to live fast and die fat and young - the sheer volume will ensure many survive into the geological record.

At any moment, there are about 25 billion live chickens in the world, making them probably the most abundant bird in history. The appearance of vast numbers of creatures five times bigger than their wild forebears will certainly strike future palaeontologists.

Clothes will also make an abrupt entry into humanity's fossil record. For millennia, they were made from natural and easily rotted materials such as cotton, linen and silk. Today, the world's growing population often wears mass-produced synthetic garments that are rapidly dumped.