Research led by scientists at the University of Southampton, in collaboration with institutions from Canada and China, offers new evidence about the intensity and scope of the Late Antique Little Ice Age, a climatic episode that occurred in the 6th century and may have played a key role in the collapse of the Roman Empire.

The international team of geoscientists focused their work on a unique finding: a group of unusual rocks located on an elevated beach terrace on Iceland’s western coast. These rocks, apparently transported there by icebergs, are linked to a brief but intense glaciation that began around the year 540 AD and lasted for approximately two or three centuries.

For decades, historians have debated to what extent climate cooling may have influenced the decline of the Roman Empire. This new study provides physical evidence that reinforces the hypothesis that an episode of abrupt, albeit short-lived, cooling may have worsened an already deteriorating political and economic situation, triggering mass migrations that transformed the map of Europe at the time.

Regarding the collapse of the Roman Empire, this climate change may have been the straw that broke the camel’s back, said Professor Tom Gernon, Earth Sciences specialist at the University of Southampton and co-author of the research.

rocks iceland empire roman ice age
Coastal Greenland, where the rocks analysed in the study were pinpointed to. Credit: Professor Ross Mitchell / The Institute of Geology and Geophysics, Chinese Academy of Sciences

The researchers argue that this glaciation was triggered by a series of three major volcanic eruptions, whose ash emissions would have blocked sunlight, causing a significant drop in global temperatures.

The investigation began with a geological mystery: the presence of rocks that, by their nature, do not match the types of formations currently present in Iceland. We knew these rocks looked out of place, because they don’t resemble anything found in Iceland today, but we didn’t know their origin, explained Dr. Christopher Spencer, Associate Professor at Queen’s University in Kingston, Ontario, and lead author of the paper.

His colleague, Professor Ross Mitchell of the Institute of Geology and Geophysics at the Chinese Academy of Sciences (IGGCAS), added: On the one hand, it’s surprising to see anything other than basalt in Iceland; but when you first see these rocks, you immediately suspect they arrived carried by icebergs from Greenland.

To identify the exact origin of the rock fragments, scientists analyzed microscopic zircon crystals contained in the samples. These minerals, known for their ability to preserve precise geological information, were separated after carefully crushing the collected rocks.

rocks iceland empire roman ice age
Collection of ancient rocks analysed in the study, which have been traced to geological provinces of Greenland. Credit: Dr Christopher Spencer / Queen’s University, Canada

Zircon acts like a time capsule that retains essential data, such as the date it crystallized and its chemical composition, Spencer explained. The combination of age and compositional characteristics allows scientists to pinpoint specific areas of Earth’s surface, much like fingerprints in criminology.

The temporal diversity of the analyzed fragments spanned nearly three billion years, or two-thirds of the planet’s history. This remarkable antiquity made it possible to link the rocks to different geological regions of Greenland, whose terrains reflect an amalgam of formations ranging from 500 million to 3 billion years old.

This is the first direct evidence that icebergs transported Greenland-origin rocks to Iceland, noted Spencer. According to Professor Gernon, the fact that the rocks come from nearly all geological regions of Greenland supports their glacial origin. As glaciers advance, they erode the ground and carry materials from various sources, creating a chaotic mix that becomes trapped in the ice.

The study determined that these glacial deposits were left in Iceland during the 7th century, coinciding with a climatic phenomenon known as the Bond Event 1. The beach terraces where they were found gradually rose due to the slow rebound of the land following the melting of the ice sheets. The timeline matches a known episode of massive ice transport, during which enormous glacial fragments broke off, crossed the ocean, and, upon melting, dispersed sediments on distant shores, said Gernon.

Spencer concluded by highlighting the value of these findings for understanding global climate dynamics: What we’re seeing is a powerful example of how interconnected the climate system is. When glaciers grow, icebergs break off, ocean currents are altered, and landscapes are transformed. Iceberg activity driven by climate may have been one of the many chain-reaction consequences of that sudden cooling.

SOURCES

University of Southampton

Christopher J. Spencer, Thomas M. Gernon, Ross N. Mitchell; Greenlandic debris in Iceland likely tied to Bond event 1 ice rafting in the Dark Ages. Geology 2025; doi: doi.org/10.1130/G53168.1

  • Share on:

Discover more from LBV Magazine English Edition

Subscribe to get the latest posts sent to your email.

Something went wrong. Please refresh the page and/or try again.

Follow LBV Magazine on Google News