Ancient Greenland rocks in Iceland reveal effects of Late Antique Little Ice Age

A trio of researchers has found evidence of the impact of the Late Antique Little Ice Age on Iceland almost 1,500 years ago. In their paper published in the journal Geology, Christopher Spencer, Thomas Gernon and Ross Mitchell describe their analysis of out-of-place rocks they found embedded in cliffs on Iceland's west coast and what they learned.

Prior research has shown that the Earth's northern hemisphere underwent a chilly spell starting around 540 AD due to the eruption of several huge volcanoes, which spewed so much debris into the atmosphere that the skies darkened. That cold spell was the start of what has now been called the Late Antique Little Ice Age—a cold period that lasted for approximately 200 to 300 years. Some historians have speculated that the sudden chill led the Goths to attack the Romans in Europe, as they sought to move south into warmer regions, leading to the final collapse of the Roman Empire.

In this new effort, the research trio were in Iceland studying some cliffs on the western shoreline when they noticed what they described as rocks that looked out of place. Curious about their nature, they collected several to study at the lab.

In their lab, the team crushed the rocks and looked at their remnants under a microscope, allowing them to pull out zircon crystals from their centers. Such crystals, the researchers note, can be used as a time capsule. By studying their age and chemistry, they were able to trace their place of origin to rock fields across Greenland. This meant that they had been moved to the shore by someone or something more than 1,500 years ago.

The researchers noted that the age of the rocks put them at the onset of the Late Antique Little Ice Age, which suggested that the rocks had been moved when ice broke free from Greenland's larger glaciers that formed as conditions had grown colder during that period.

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