In a stunning discovery, UCL (University College London) researchers have found that Ireland and Scotland are hosting a rock formation which may be carrying the rare and complete record of “snowball Earth”.
The research, which was published in the Journal of the Geological Society of London, discovered that the Port Askaig Formation is filled with layers of rock which are up to 1.1km thick and were probably deposited between 662 to 720 million years ago when the Sturtian glaciation occurred.
This was the first time the world had frozen and led to the development of complex and multicellular organisms.
In this rock formation, an exposed outcrop on Scottish islands, which was known as the Garvellachs, was unique because it shows how there was the transition of warm and tropical Earth into “snowball Earth”.
Some other rocks which were formed at a similar time in North America and Namibia have been missing this transition.
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UCL Earth Sciences senior author Professor Graham Shields said, “These rocks record a time when Earth was covered in ice. All complex, multicellular life, such as animals, arose out of this deep freeze, with the first evidence in the fossil record appearing shortly after the planet thawed.”
UCL Earth Sciences PhD candidate and first author Elias Rugen said, “Our study provides the first conclusive age constraints for these Scottish and Irish rocks, confirming their global significance.”
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“The layers of rock exposed on the Garvellachs are globally unique. Underneath the rocks laid down during the unimaginable cold of the Sturtian glaciation are 70 meters of older carbonate rocks formed in tropical waters. These layers record a tropical marine environment with flourishing cyanobacterial life that gradually became cooler, marking the end of a billion years or so of a temperate climate on Earth,” he added.
“Most areas of the world are missing this remarkable transition because the ancient glaciers scraped and eroded away the rocks underneath, but in Scotland, by some miracle, the transition can be seen,” Rugen said.
The Sturtian glaciation period lasted for 60 million years on Earth and was one of the two major freezing periods in the Cryogenian Period (between 635 and 720 million years ago).
(With inputs from agencies)