720 million years ago, Earth underwent a dramatic transition from a tropical environment to an ice age over the span of a few thousand years.
Scientists have characterized this transformation as quite “brutal” for the Earth, with the only geological evidence found in Scotland.
More than 700 million years ago, Earth experienced one of the most extreme ice ages.
The Golden Nail at Bogalino, showcasing the continuous transition between two geological phases at a reference site (Photo: Wikimedia Commons).
For 60 million years, the average temperature of the Earth significantly dropped, transforming our planet into a massive ice globe, a period known as the Sturtian Ice Age.
Despite this intense cold period, life still existed, hidden beneath the ocean’s depths. However, it manifested in very primitive single-celled organisms, which may have been crucial for the development of life on Earth.
Recent studies suggest that these harsh living conditions challenged life on land, driving the emergence of multicellular organisms toward the end of the ice age.
Consequently, the extremely rapid climate fluctuations during the Cryogenian Period could have been a catalyst for natural selection, pushing organisms to quickly adapt to vastly different living conditions.
Ice Age Sediment Samples
The causes and evolution of the Sturtian Ice Age help humanity understand an important phase not only in terms of Earth’s overall history but also the history of life itself.
Several locations worldwide have rock formations that bear witness to this period, although most are incomplete. They allow scientists to observe a fragment of the Sturtian Ice Age.
According to scientists, the Port Askaig Tectonic Plate (1.1 km thick), a rock layer stretching from Ireland to Scotland, may have recorded the entirety of this phase.
This provides incredibly valuable information about the conditions that led to the onset and conclusion of the Sturtian Ice Age.
Severe Climate Transition
New research reveals the precise dating of the rocks in Scotland, indicating that their sediments—originating from this ice age—were deposited between 662 and 720 million years ago, encompassing the entire period when the Earth was completely frozen.
Additionally, the rocks of this stratigraphy lie on an ancient carbonate foundation formed in tropical seas, enabling the research team to clearly observe the gradual transition from a warm environment (rich in cyanobacteria) to a frozen one.
This transformation has been remarkably preserved, leading to the Port Askaig Tectonic Plate being regarded as a Global Stratotype Section and Point, also referred to as the “Golden Nail”—a site where we can clearly observe the transition between two geological phases.
The name “Golden Nail” stems from the International Commission on Stratigraphy (ICS), established as a reference point for this geological transition, which has now become a tourist attraction for those wishing to learn about Earth’s history.
