The Islands of Scotland
Scotland is a nation overflowing with history and culture, bringing in millions of visitors annually. From Medieval castles to scenic landscapes full of native animals, it remains one of the most alluring countries in Europe.
Source: Wikimedia
The nation is nestled at the furthest reach of Western Europe and has close to 800 islands, most of which are uninhabited.
The Hebrides of Scotland
One particular group of islands, the Hebrides, is adored by visitors from around the world who visit to indulge in the Gaelic culture that continues to permeate throughout the local communities.
Source: Wikimedia
However, more recently, they have played an integral role for scientists who are investigating an ancient event that saw Earth transition from a tropical climate into a ball of ice.
Glaciers Begin to Cover the Earth
The Hebrides are divided into two main sections: the Inner and the Outer Islands. Scientists working on the Inner Hebrides discovered unique rocks that show clear signs of when the Earth plunged into a deep freeze.
Source: Wikimedia
According to their research, the rocks date between 720 million and 662 million years old and showcase the rare event in which our planet transitioned from a warm tropical climate to a “snowball Earth,” which saw the vast majority of its surface covered in glaciers.
Why Did the Earth Turn Into an Ice Ball
According to scientists, consecutive ice ages occurred during the same time frame, which may have happened because most of Earth’s landmasses were located close to the equator, resulting in weathering.
Source: Wikimedia
Researchers define weathering as a process in which precipitation and wind begin to break down rocks and minerals on Earth’s surface. This results in lower carbon dioxide levels, which in turn allows an excessive amount of heat to leave the surface, essentially cooling the planet.
The Earth’s Oceans Froze Over During Snowball Event
Melissa Hage, an environmental scientist and assistant professor at Oxford College of Emory University in Georgia, explained, “Increased continental weathering led to a decrease in atmospheric carbon dioxide and [therefore, caused] global cooling.
Source: Wikimedia
She added, “Once the polar oceans began to freeze, more sunlight was reflected off the white surfaces, and cooling was amplified.”
Rock Showcase the Transition to a New Geological Era
Scientists believe the rocks discovered on the Inner Hebrides showcase a “golden spike” associated with this event, meaning they serve as a marker for the transition into a new geological age.
Source: Wikimedia
While the theory has yet to be confirmed, the researchers propose it marks the transition between the Tonian period, which lasted from 1 billion to 720 million years ago, and the Cryogenian period, which began 720 million years ago and ended 85 million years later.
Scotland Provides Scientists With Rare Insight Into Snowball Earth Event
The study’s first author, Elias Rugen, a researcher at University College London’s Earth Sciences department, explained the implications of the findings.
Source: Wikimedia
“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,” she said.
Two Major Snowball Events
Researchers propose two major snowball Earth events that occurred during the Cryogenian period: the Sturtian glaciation and the Marinoan glaciation.
Source: Wikimedia
The Marinoan event was extremely severe and lasted for a staggering 57 million years, whereas the Sturtian event lasted for around 15 to 20 million years.
Scientists Examine Tiny Crystals Within the Scottish Rocks
The researchers meticulously analyzed the rocks from the Scottish Hebrides and published their findings in the Journal of the Geological Society of London. They collected samples from two formations on the Garvellachs and proceeded to examine the tiny crystals within, known as zircons.
Source: Wikimedia
As the zircons contain uranium, a radioactive element that decays at a persistent rate, they could discern when the rocks originally formed.
The Rocks Formed During a Tropical Period
After carefully analyzing the results of their tests, the scientists discovered that the lower sections of the rock formed when the Earth experienced a much warmer and tropical climate.
Source: Wikimedia
“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,” Rugen said.
A Rare Glimpse of the Ancient World in Scotland
According to Rugen, Scotland provides us with a rare glimpse into our planet’s climate before the major glacial periods that resulted in the snowball Earth event occurred.
Source: Wikimedia
Adding, “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.”