A study of Scottish rocks has revealed a previously unknown ice age.
Scientists from Aberdeen University of Aberdeen analysed rocks in the Torridon area of the north-west Highlands and uncovered evidence of debris from melting icebergs in lakes.
The rocks date from the period known as the ‘boring billion’ which took place from 1800-800m years ago.
The term is used by geologists to describe what was thought to be a relatively calm period in Earth’s evolution, with little climatic upheaval.
However, this latest discovery suggests the era may have included another ice age.
Professor Adrian Hartley led the study – published in the Scottish Journal of Geology – along with colleagues from the university’s School of Geosciences.
Prof 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.”