Rocks on the coast of Iceland couldn’t possibly tell us anything about the Roman Empire. Or could they? According to a study in Geology, a collection of rocks on Iceland’s coast reveals the severity of the Late Antique Little Ice Age — a period of climate change that may have contributed to the Roman Empire’s collapse.
“When it comes to the fall of the Roman Empire, this climate shift may have been the straw that broke the camel’s back,” said Tom Gernon, a study author and a professor at the University of Southampton in the U.K., according to a press release.
A Climate-Change Collapse
Though the collapse of the Roman Empire can be tied to a variety of factors, recent research has suggested that an ice age began on Earth in the 500s C.E., at about the time of the decline of the Roman Empire. Generated by ash clouds from three separate volcanic eruptions around 540 C.E., this ice age — the Late Antique Little Ice Age — blocked out the sun and cooled the surface of Earth for some 200 to 300 years, potentially playing a part in the empire’s end.
But just how severe was this Late Antique Little Ice Age? Pretty severe, the new Geology study finds. Showing that large, round rocks — or cobbles — on the coast of Iceland came all the way from the coast of Greenland in the 600s C.E., the study demonstrates that the Late Antique Little Ice Age had dramatic impacts on Earth’s geology, depositing rocks in unusual places by way of glacial ice and icebergs.
“This is the first direct evidence of icebergs carrying large Greenlandic cobbles to Iceland,” said Christopher Spencer, a study author and a professor at Queen’s University in Canada, according to the release.
Ultimately, the study provides insights into the impacts of the Late Antique Little Ice Age, highlighting its intensity and supporting the theory that it contributed to the death of an already dying empire.
Read More: Ancient Lead Poisoning May Have Contributed to the Roman Empire’s Downfall
Revealing the Late Antique Little Ice Age Through Rocks
Of course, to the average observer, an assembly of rocks on Iceland’s western coast would’ve looked like nothing special. But to a researcher, the cobbles screamed of something unusual. “We knew these rocks seemed somewhat out of place because the rock types are unlike anything found in Iceland today, but we didn’t know where they came from,” Spencer said in the release.
Representing a mix of basaltic and non-basaltic cobbles, the collection seemed strange, thanks, in part, to its composition.
“On one hand, you’re surprised to see anything but basalt in Iceland; but having seen them for the first time, you instantly suspect they arrived by iceberg from Greenland,” said Ross Mitchell, another study author and a professor at the Institute of Geology and Geophysics, Chinese Academy of Sciences, according to the release.
Testing that assumption, the study authors smashed the rocks and examined the tiny crystals, called zircons, that were trapped inside.
“Zircons are essentially time capsules that preserve vital information, including when they [crystallized] as well as their compositional characteristics,” Spencer said in the release. Assessing these characteristics, the study authors traced the zircons’ origins to Greenland and to time periods between 0.5 billion and 3 billion years ago.
Importantly, the zircons indicated where in Greenland the rocks originated — an important clue for tracing their journey from Greenland to Iceland in the 700s C.E.
“The fact that the rocks come from nearly all geological regions of Greenland provides evidence of their glacial origins,” Gernon said in the release. “As glaciers move, they erode the landscape, breaking up rocks from different areas and carrying them along.”
According to the study authors, the cobbles may have traveled to Iceland when ice broke away from Greenland’s glaciers, then drifted across the ocean, then melted on Iceland’s shores, where it dropped its rocky debris.
“What we’re seeing is a powerful example of how interconnected the climate system is. When glaciers grow, icebergs calve, ocean currents shift, and landscapes change,” Spencer said in the release.
Testifying to the intensity of the era’s climate change, the rocks’ arrival in Iceland stresses that the Late Antique Little Ice Age was severe, with a wide variety of consequences around the time of the Roman Empire’s collapse. “Climate-driven iceberg activity may have been one of the many cascading effects of rapid cooling,” Spencer concluded in the release.
Read More: Income Inequality May Have Caused the Collapse of the Roman Empire and Han Dynasty
Article Sources
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Sam Walters is a journalist covering archaeology, paleontology, ecology, and evolution for Discover, along with an assortment of other topics. Before joining the Discover team as an assistant editor in 2022, Sam studied journalism at Northwestern University in Evanston, Illinois.
