Huge, 'Impossible' Crystals in Denmark Have Finally Been Explained by Scientists - ScienceAlert

In the global greenhouse conditions of the early Eocene (56-48 million years ago), how did huge numbers of giant glendonite crystals manage to form?

These rare calcium carbonate crystals - that need temperatures lower than 4 degrees Celsius to form - are composed from the mineral ikaite and found in their tens of millions on the Danish islands of Fur and Mors.

After a detailed chemical analysis of glendonite samples by Thibault and an international team of researchers, using a technique called clumped isotope thermometry to trace temperatures back millions of years, we may have an answer: the Eocene was perhaps not as uniformly warm as previously thought.

We may not have the sky blotted out by volcanic ash anytime soon, but a quickly changing climate is something we are going through – just like parts of the world were more than 50 million years ago, long before humans arrived on the scene