Ancient footprints on Beringia

Kodiak Island grass bluff view bay
View from an archaeological site with ancient sod houses located on Alaska’s Kodiak Island / FrontierScientists footage

You can see the depressions in the earth when the archaeologists point them out. Each house had a central room connected by tunnels to side rooms. Female relationships guided living arrangements: in a grandmother’s house, each of her daughters’ families would occupy one of the small side rooms. When they gathered there in rooms partially dug into the earth with walls built up with driftwood or whale bone and covered by sod, they achieved safety and warmth even during harsh Alaskan storms.

Of course this archaeological snapshot from Kodiak Island is only one piece of rich human culture and heritage. The staggeringly swift climate change that today is increasing temperatures, destabilizing permafrost, melting glaciers and exposing coasts to intense storm surges and rising sea levels is threatening Arctic archaeological sites that record a mighty history of humans struggling against harsh conditions, and surviving.


Roughly 20.000 years ago saw the last glacial maximum, the height of an Ice Age. Frigid temperatures had gathered immense ice sheets and their colossal weight was so great that it actually pressed the landmasses they rested on deeper into the earth. Since ice was trapped on land in ice sheets that measured up to 9,842.5 feet [3 kilometers] deep, sea levels were considerably lower than they are today. Continental shelves near present-day Russia and Alaska lying today under shallow seas were exposed to the air, forming a connection between the continents that we call the Bering Land Bridge. Taken together, parts of Russia, the exposed land bridge, and parts of Alaska formed a region we call Beringia. Beringia facilitated the first human migration into North and South America.

Bering Land Bridge illustration
Hand-drawn map. Yellow color illustrates currently submerged continental shelf regions that were once exposed to the air, some of which formed the Bering Land Bridge / Image Frank Kelley (PolarTREC 2008), Courtesy of ARCUS

The people then were hunter-gatherers, following herds of migratory animals like caribou, mammoth, muskox and bison as they ranged the grassland steppes of Beringia. This ‘bridge’ was not just a narrow stretch swiftly crossed and severed, as I’d once imagined. It was an expansive land. Over many thousands of years Beringia hosted humans and animals and underwent environmental changes in response to the slow natural shifts in Earth’s climate. Unlike much of North America, Beringia was never covered in an ice sheet– the land provided a haven.

Open routes

It wasn’t until roughly 12,000 years ago that the great ice sheets’ melt and retreat finally opened land passages that could allow human settlement in interior North America. A population of people who had originated in Asia but long lived independent of Asia on Beringian lands finally entered North America proper. Some theorize that settlers also used boats to travel the coast; perhaps making use of the ocean coasts allowed them to spread southward while interior land routes were still made impassable by ice.

Advancing civilization

Archaeological sites in Alaska show a succession of rich ways of life and different cultures. The people who made it through that challenging time were amazing! These settlers faced and tackled harsh environments, inventing and improving tools, crafting cultural traditions, establishing hunting camps, settlements, and trade routes. Today, Alaskan archaeological sites that show evidence of a subsistence lifestyle can be found near where modern-day Native people practice the same techniques– because they work. These are skills custom-tailored to survival in Alaska.

The people who lived during the last 20,000 years in Beringia and then North America had to adapt to make the best use of continually changing living conditions and resources. Their settlements, tools and art help us understand the spread of technology and culture through the Arctic and beyond.

Evidence from archaeological sites can provide a record of past climate. Studying the rings on clam shells left over from past peoples’ meals lets scientists determine ancient temperatures and environmental conditions. Archaeological sites are not only cultural records, but also paleoclimate records. More complete climate records let scientists refine climate models, simulations that let us more accurately understand and predict contemporary and future climate conditions.

Alaska coast erosion permafrost degradation
Coastal erosion and permafrost degradation takes its toll on Alaska’s coast. “Where the Esook Trading Post once stood.” / Courtesy Benjamin Jones, USGS

Losing the coast

Today rising temperatures, destabilizing permafrost, and coastal erosion are forcing parts of Alaska’s coast into the sea. As sea ice lessens in extent and thickness the region sees higher storm surges driven by wind across open water. The lack of year-round shorefast ice (shoreline ice) means that communities near the ocean are more vulnerable to fierce storms and to wave-driven erosion.

BLM Alaska lands coast erosion loss satellite view
Bureau of Land Management -controlled lands in northern Alaska impacted by coastal erosion. “Compare the coastline on these satellite maps showing 1955 and the same area in 2009.” / Courtesy Benjamin Jones, USGS

According to the U.S. Government Accountability Office, out of more than 200 native Alaskan villages, 85% are affected by erosion and flooding. 31 face imminent threat. Some, like Kivalina, make the choice to completely relocate in the face of ground loss. Shoreline loss at Kivalina averaged 35 feet annually. Storms were worse. One 2005 storm claimed 70 feet of beach for the ocean.

Of course, the coast has changed in the past. As the ice sheets melted and Beringia flooded, the rising sea levels inundated land where people had lived for thousands of years. There are nearly certainly many archaeological sites on the bottom of the Bering and Chukchi Seas. Meanwhile, beach fronts change shape and elevation for various reasons. Storms, wind and wave direction can bring in windblown sand and marine deposits to build up beaches, or can tear them away. Over time land that was once compressed by the weight of ice sheets rises, gaining elevation through isostatic rebound.

But changes like those happen very slowly over the course of millennia. Modern-day changes since the Industrial Revolution have driven incredibly rapid climate shifts. Global warming is robbing the Alaskan coast of the cultural resources and data that can be found in archaeological sites.


Near Barrow, Alaska, the northernmost town in the state, sits the site of an ancient settlement. Nuvuk was occupied by Thule culture people (Iñupiat ancestors) for more than a millennia until the 1930s. Now Nuvuk is unoccupied. The coastline next to the settlement is eroding into the ocean.

Excavations were undertaken at the Nuvuk cemetery, where the eroding gravel beach threatened to lose several hundred burial sites, buried human remains and artifacts to ocean waves. The archaeologists who led the Nuvuk project gained help from local North Slope high school students, a cooperative effort that preserved ancient remains and taught students about archaeological field studies and about the past.

Nuvuk archaeological site beach
Beach at the Nuvuk Archaeology Site near Barrow, Alaska / Image Frank Kelley (PolarTREC 2008), Courtesy of ARCUS

With the consent and aid of local Natives, anthropological geneticist Dennis O’Rourke of the University of Utah collected DNA samples from the bones of the buried Thule people and from modern-day Natives. The data can help paint a picture of genetic diversity and spread through the area.

Evaluating sites

Sites like Nuvuk and others like Karluk One, Raven Bluff, Lake Matcharak, and excavations in public lands including Cape Krusenstern National Monument and Gates of the Arctic National Park & Preserve give us precious glimpses into human history. Tools used, works of art created, and even bones tossed on middens (trash heaps) paint a picture of Native ingenuity and perseverance. These settlers used the world around them and adjusted to ever-changing conditions.

Patrick Saltonstall, anthropologist, Alutiiq Museum & Archaeological Repository curator, relates in the video This Sod House how ancestral populations on Kodiak Island brought light to their homes using whale oil in the time before forest ranges had spread back north to Alaska following the ice sheets’ long regime.

“The hearth, that’s the focus of the house: where you cook, light. Everything. And it’s actually interesting if you go to really old Alutiiq houses, 7,000 years ago, they don’t really have a hearth. And if you think– the reason why is because there’s no driftwood; the trees weren’t built up yet. And there we find these boat-shaped lamps and they have wicks all along the edges and that’s because they used the whale oil, the seal oil, to both cook, heat, and light. In later prehistoric houses like this house they would use the hearth because they had a lot of wood. So you would do all your cooking and heating with this and then the oil lamps have only one little wick spot because they’re only using them for light.” ~Patrick Saltonstall

Laura Nielsen 2015

Frontier Scientists: presenting scientific discovery in the Arctic and beyond