The Faroe Islands, a remote archipelago between Norway and Iceland, was one of the last places settled by humans. Archaeological and historical evidence has suggested that Vikings were the first to arrive on the scene, appearing by the mid-9th century. Circumstantial evidence such as carbonized barley grains, however, has led some historians to propose that others had settled the islands centuries earlier.
An earlier settlement date aligns with paleoenvironmental proxies, such as pollen records and soil erosion, which show that the islands underwent profound environmental change before the 9th century. Researchers now have dated a sedimentary lake core from the Faroes using radiocarbon samples and cryptotephra horizons—ultrathin layers of volcanic ash invisible to the human eye. The sediment core shows that humans indeed left their mark on the islands some 300 years before the first major Viking settlement.
“This is the first unequivocal evidence of people being on the Faroes” before 900 CE, said Lorelei Curtin, a postdoctoral researcher at the University of Wyoming in Laramie. “This really revises the timeline for the population of the North Atlantic.” Curtin and her colleagues presented the research at AGU’s virtual Fall Meeting 2020. The results were published in Communications Earth and Environment.
Horizons of Glass and Ash
The new study relied on layers of cryptotephra left by volcanic ash from Iceland, the collection of still-active volcanic islands less than 700 kilometers northwest of the Faroes. “Tephra, by definition, is just volcanic ash or any fallout from volcanic eruptions,” said Nicholas Balascio, a paleoclimatologist at the College of William and Mary in Williamsburg, Va., who identified tephra layers for the study.
Glass from every volcanic eruption has a unique chemical signature, allowing scientists to date sediments based on when an eruption took place.
When a volcano erupts in Iceland, it projects microscopic shards of glass into the atmosphere. This volcanic ash can travel vast distances and affect travel, agriculture, and human health. Volcanic ash from Iceland can make its way to the Faroes, where it settles into lake sediments in discrete layers. Glass from every eruption has a unique chemical signature, allowing scientists to date sediments based on when the eruption took place.
Balascio used chemical signatures to identify five tephra layers in a sediment core extracted from beneath Lake Eiðisvatn in the Faroe Islands. The core contained 10,000 years’ worth of slow but steady depositional layers. Among these was the Landnám tephra, formed around 870 CE—a few decades after the Vikings arrived in the Faroes.
If Vikings had gotten there before any other settlers, the researchers would have expected to find no preserved imprints of human activity below the Landnám tephra. However, the team detected ancient sheep DNA and other molecular biomarkers in a layer of sediment 20 centimeters deeper, representing about 300 years. The presence of sheep, which aren’t native to the Faroes, strongly suggests that people indeed had occupied those remote outposts around 500 CE.
“It’s a novel approach to a question that’s been going on for 30 years,” said paleoecologist Gina Hannon of the University of Liverpool who was not involved in the study. “It’s really contributing to a discussion that hasn’t been fully resolved.”
An Evolving Landscape
What happened to the Faroes to transform them from wooded wonderlands into soil-poor grassy knobs?
Almost nothing is known about these early settlers. But evidence of their presence in the Faroes helps illuminate one question that has plagued paleoclimatologists for decades: What happened to the Faroes to transform them from wooded wonderlands into soil-poor grassy knobs?
“[The archipelago] seems like an untouched landscape, but it’s been heavily modified by humans and livestock,” said Curtin.
The new results could help paleoclimatologists better understand the scale of human activity in the Faroes, how quickly humans alter environments in the North Atlantic, and how to interpret the signals humans leave behind.
The findings also open the door to using geological methods to track human migration in the North Atlantic and elsewhere. These methods can reveal faint traces of human activity that would likely go unnoticed in traditional archaeological or paleontological excavations.
“These people didn’t leave archaeological imprints,” said Hannon. “But what they did leave [were] footprints in the soil.”
—Freda Kreier (@FKreier), Science Writer