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Phoenix666 writes:

It's official. Our presence on Earth has been written in the stones:

These sedimentary formations are produced by the intergranular precipitation of carbonate cements (CaCO3). "A cement has formed between the various sediments. So the sand, instead of being loose as on normal beaches, forms these rocks," explained Arrieta.

Yet even though the cements that the beachrocks are made of are carbonates, the geological formations on the coast also have ferruginous cements. The slag trapped in the cemented blocks has undergone dissolution processes as a result of meteorization or atmospheric events such as acid rain, and has even re-precipitated in the pores as insoluble iron salts. The research focused on the characterisation of these cements.

Firstly, to study the types of cements, innovative spectroscopic techniques were applied and which allowed the various mineral phases to be thoroughly analysed. "On a microscopic scale, various layers of cement appear, and each one provides information on the moment when they precipitated, the conditions that existed, etc.," said Arrieta.

Secondly, the researchers analysed the materials trapped in these cements where "we found foundry slag from the industrial revolution, even waste bearing the seals of European companies that used to dump their slag when they arrived with their vessels. That is why we can find the so-called technofossils or traces of human activity on the beaches, in this case the industrial waste of international companies, which helps to calculate the age of the beachrock."

"Technofossils." It's an actual thing, not just a cheeky nickname for COBOL programmers.

Original Submission