Research Article| April 10, 2025

18/08/2025 Evidence for a rapid anthropoclastic rock cycle

https://doi.org/10.1130/G52895.1

Abstract

Humans generate, transport, and subsequently deposit vast quantities of natural and anthropogenic waste material across the globe. However, the subsequent redistribution and lithification of this material is yet to be understood. Here, we document a rapid “anthropoclastic rock cycle” in a coastal setting, with the formation of an anthropogenic rock through the erosion, transportation, deposition, and lithification of legacy waste material that has occurred over <150 years. Field observations from West Cumbria, UK (a major iron and steel making area in the nineteenth and twentieth centuries), have identified a cemented conglomerate-like rocky foreshore platform that is dominantly composed of slag clasts (by-product from iron and steel making). Clast shape and sedimentary structure analysis demonstrates that the material has eroded from an adjacent slag heap and has been transported and deposited by natural coastal processes. Microstructural and geochemical analyses have identified calcite, goethite, and brucite cements, with anthropogenic material (e.g., aluminum can tab) indicating cementation has occurred within the past 35 years. These results indicate that lithification is unprecedently fast for a clastic rock, and this process is driven by the chemistry of the waste material. The recognition of a rapid anthropoclastic rock cycle challenges conventional understanding of the natural clastic sedimentary rock cycle, with anthropoclastic rocks forming over decadal time scales rather than thousands to millions of years. Our findings highlight the need for updates to rock coastal models as new anthropogenic landforms and materials are forming, with important implications for changing coastal dynamics and the management of anthropogenic landscapes.

Le nombre de débris spatiaux dont la taille est supérieure à 1 mm est quant à lui estimé à environ 128 millions. Le risque de collision est particulièrement élevé dans certaines zones, comme l’orbite terrestre basse, où se concentrent beaucoup de satellites.

Il y a 20 ans le New Scientist avait publié un article intitulé

“Imagine Earth without people”, »Comment serait la Terre sans les humains ». Il s’agissait d’une expérience de pensée visant à imaginer ce ce que serait la planète sans une présence humaine continue ayant duré plus de 200.000 ans.

Dans cet article publié par la Revue Geology, des chercheurs de l’université de Glasgow UK, commentent la découverte d’un processus géologique suggérant que la Terre, en fait, ne nous oublierait pas.

Ils étudiaient la géologie de la zone industrielle de Derwent Hove https://www.workingtonnaturepartnership.co.uk/ sur la cote de Cumbria, UK . Pendant 125ans, depuis le milieu du 18e siècle years, starting in the 1850s, Derwent Howe fut un important centre d’aciéries, générant des collines entières de cendres et poussières de charbon et de fer. Ce furent environ 27 million de métrés cubiques qui furent déposés le long de 2 kms de rivages.

When the Glasgow researchers went to the beach, they found a series of outcrops made from an unfamiliar type of sedimentary rock. The beach used to be sandy, so the rock must have been a recent addition. It was clearly clastic, meaning it was composed of fragments of other rocks and minerals (clasts) that have been cemented together in layers. On closer inspection, they found that the clasts were derived from the slag heap. The only conclusion was that material was eroding from the slag, being washed into the sea, depositing onto the shore and then turning rapidly into rock.

And when I say rapidly, I mean rapidly. The formation of clastic rocks usually takes thousands or even millions of years. But here it was happening in decades – a blink of an eye in geological terms. The slag has been there in large quantities for only a century or so.

Rock on the Cumbrian coastline Industrial waste is turning to rock in just decades, research reveals

University Of Glasgow

Even more remarkably, the team found two artefacts firmly entombed in the clast that prove unbelievably rapid rock formation, or lithification. One was a penny coin minted in 1934. The other was an aluminium ring pull-tab from a drink can that could be no more than 36 years old. In other words, lithification is occurring within decades. The researchers propose that this is an entirely new geological process called the “anthropoclastic rock cycle”.

The researchers propose that this is an entirely new geological process, the ‘anthropoclastic rock cycle’

“What’s remarkable here is that we’ve found these human-made materials being incorporated into natural systems and becoming lithified over the course of decades,” team leader Amanda Owen told the University of Glasgow’s press office. “It challenges our understanding of how a rock is formed, and suggests that the waste material we’ve produced in creating the modern world is going to have an irreversible impact on our future.”

As at Derwent Howe, so all over the world. Similar rocks were discovered near Bilbao, Spain, in 2022, but couldn’t be securely dated. Slag waste is a global phenomenon, and it is probably being turned to rock anywhere it comes into contact with ocean waves, according to team member David Brown.

On the surface, that might seem like a problem, and indeed we don’t yet know what the environmental impacts of such processes are. But maybe the discovery is good news. If industrial waste is being locked away in solid rock, surely that is a nice, neat way of dealing with it without having to actually deal with it, right? The rocks at Derwent Howe also contained fragments of clothing, plastic, car tyres and fibreglass, which otherwise litter the environment. Maybe rapid lithification would be a good way to dispose of our detritus.

There is another upshot of the research. For decades, earth scientists have been disagreeing over whether to designate a new geological epoch called the Anthropocene, to recognise that humans have replaced natural processes as the dominant influence on the Earth system. I’m a big supporter of the concept because it underscores the extent of our perturbation of the natural processes that kept Earth habitable and safe for people for millennia. Last year, however, the International Union of Geological Sciences voted not to accept the Anthropocene because of a squabble over when it began.

Surely now is the time to reverse that decision. Our influence on the surface of Earth is literally laying down new geology, starting about 175 years ago. Future civilisations will be able to see it and study it. If that isn’t a new geological epoch, then what is?

Graham’s week