After studying rocks in Scotland, geologists have found evidence of a previously unknown ice age, shedding new light on the evolution of the Earth.
The rocks date back to the period known as the ‘boring billion’ which occurred between 1800 to 800 million years ago. The term is used by geologists to describe what was thought to be a relatively slow period in the Earth’s evolution, with little climatic disruption.
This latest discovery suggests the era may have contained another ice age to add to those that have transpired throughout Earth’s history.
Study leader, Professor Adrian Hartley, said: “In Earth’s middle ages it is thought that not very much happened on the planet.
“Throughout this so-called ‘boring billion’ the global climate was temperate and unchanged. Life was limited to algae in the ocean, the land was completely barren and oxygen was 10 per cent of what it is now.
“Until now, no evidence for climate change had been discovered but our study has shown there was ice at Earth’s surface during this period.
“We made the discovery by analysing silty lake sediments that are a billion years old, allowing us to identify locations where pebbles had fallen from melting icebergs and had formed impact features on the lake floor, deforming even older layers of sediment.
“Similar studies have allowed us to reconstruct the recent glacial history of the Earth, but this takes us much further back in time to when Scotland was located at 35°S – the same latitude as South Africa.
“It’s the first evidence globally for glaciation at this time in Earth’s history – proving it wasn’t such a boring billion after all.”