Geologists have found a complete record of the Ice Age: discovery in Scotland and Ireland sheds light on the era of 'Snowdonia Land'

This stage, which occurred 717-658 million years ago, is considered key to changing the planet's landscapes and accelerating the evolution of life. However, many details have remained unclear until now.

In a paper published in the journal Geology, Scott MacLennan and colleagues showed that the diamictites they studied are fragments of powerful boulders carried long distances by glaciers and are of glacial origin. Below, they gradually transition into older layers of carbonates: this suggests that the area was formerly a shallow sea rich in marine microflora.

According to a study published in the Journal of the Geological Society, the Port Askaig rock complex, located in the Scottish islands, contains important evidence of the Sturtian glaciation, one of the most severe episodes when glaciers covered even equatorial zones. This geological section is 1.1 kilometres thick and records both advances and retreats of glaciers, challenging the theory of a complete and continuous ice sheet.

Researchers from University College London carried out a detailed analysis of clastic zircons from the Port Askaig Formation, dating them using the uranium-lead method. The findings confirmed that the age of these minerals corresponds to the period of the Sturtian glaciation. This also indicates the destruction of the ancient continent of Laurentia by glaciers, which supports the hypothesis of partial and mobile glaciation.

One of the unique discoveries was the exposure of rocks on the Scottish islands of Garwells. Here there is a record of climate change from a warm tropical climate that preceded cryogenesis to a severe ice age. Such a record is not found in other places such as North America or Namibia, making this a special place to study.

The first author of the study, Elias Rugen, said that this is the first time scientists have been able to establish the exact age of rocks in Scotland and Ireland, confirming their global significance. He emphasised that the rocks in the Garwells are unique - they contain traces of an ancient marine environment where cyanobacterial life flourished, which was then replaced by a cold climate, indicating the end of a billion-year period of temperate temperatures on Earth.

With accurate dating of these rocks, scientists can now accurately mark the onset of cryogenesis, possibly leading to the creation of a new "golden nail" - a reference section that marks the lower boundary of the geological stage.

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The"Snowball Earth "era is a hypothetical period in our planet' s history when the Earth was almost completely covered in ice, even in equatorial zones. The term is used to describe global glaciation, which scientists believe occurred at the end of the Proterozoic, about 717-635 million years ago, during a period called cryogeny.

According to the hypothesis, two major glacial events, the Sturtian and Marinoan glaciations, led to a near total freezing of the entire planet. During this period, the ice sheet may have covered the oceans and land, extending from the poles to the equator. The Earth's surface may have been covered by glaciers for up to a million years, creating extreme conditions for life.

After the end of these global glaciations, significant changes in climate and evolution began. One important consequence of this period is thought to be an acceleration of biological evolution. For example, it is possible that the extreme conditions may have stimulated the development of multicellular life and led to the diversification of organisms, which eventually became the prerequisite for the Cambrian explosion, a rapid increase in the diversity of life on Earth.