When did the first Americans arrive – can we ask them?

Rimrock Draw is the type of place most people would barely notice: a small, normally dry swale flanked by a low basalt cliff in a landscape most notable for sagebrush, broad basins, and the occasional wild horse. Pretty enough if you like wide-open spaces and expansive skies, but not all that different from many other places in Oregon’s high desert.

But to geologists it tells a different story. Thousands of years ago, this land wasn’t so dry. It was a realm of giant lakes and sprawling savannahs on the well-watered fringe of the Ice Age glaciers. A time when Rimrock Draw hosted a substantial creek.

Some years ago, Scott Thomas, an archaeologist with the US Bureau of Land Management, discovered the ancient creekbed and walked its course, finding it to be teeming with arrowheads.

“They were all over the surface,” says Lexie Briggs, of the University of Oregon’s Museum of Natural and Cultural History.

Not that the points Thomas saw were all that ancient. But they did mean the site hadn’t been discovered by souvenir hunters. And the base of the cliff looked like a perfect place to rest, camp, cook meals, and otherwise hang out.

Formal excavation began in 2011, under the leadership of University of Oregon archaeologist Patrick O’Grady (who was in the field and could not be contacted for this article.) Since then, it has proven to be one of the most important archaeological discoveries in the US, pushing back the earliest known occupation of the Americas by more than 2,000 years.

There were some 60 tribes in this area, so there are lots of stories.

David Lewis

It’s also adding support for tribal stories depicting ancient events, says David Lewis, an assistant professor of anthropology and Indigenous studies at Oregon State University, who has written about these stories on his blog, the Quartux Journal.

“There were some 60 tribes in this area, so there are lots of stories,” he says. And while some go back thousands of years, he says, “some have been recognized as actual history.”

As an example, he cites a story from the Klamath tribe of south-central Oregon, about two giant volcanoes having a war. One was 4,300-meter Mt. Shasta, in northern California. The other was a 3,700-meter mountain called Mt. Mazama, in Oregon.

When the story was first collected, it sounded fanciful, in part because Mt. Mazama no longer exists. But geologists gradually came to realize that it once did, and that 7,700 years ago — about the same time Mt. Shasta was erupting, it blew its top in the biggest blast the Pacific Northwest has seen in a million years. Situated midway between the two mountains, the Klamath people witnessed it and passed it down for a staggering 350 generations. Now, Lewis says, “[Geologists] recognize it as being an actual eyewitness account.”

When the story was first collected, it sounded fanciful, in part because Mt. Mazama no longer exists.

Early in their work at Rimrock Draw, the archaeologists found a layer of volcanic ash, which Briggs describes as being like “a very clear line in the sand.”

That was exciting, because ash layers can be associated with the eruptions that produced them – eruptions that geologists have dated very precisely. Finding an ash layer is like having nature’s own date stamp in the middle of your dig. Everything above it is from before the eruption; everything below it is from after.

Initially, the archaeologists assumed they’d found ash from the eruption of Mt. Mazama – exciting enough because it meant the site was ancient. Then tests revealed that the ash came from an older eruption from Washington’s Mt. St. Helens, about 15,400 years ago.

That turned ancient into really ancient.

Better yet, there were important items below the ash layer. These included teeth from an ancient camel (long extinct); bison teeth, and stone tools that DNA testing showed to carry traces of bison blood.

COVID-19 delayed the carbon-14 dating results, but they are now back, and the data is astounding: the teeth are 18,250 years old. Some of the tools could be older, including a stone scraper O’Grady has described as “America’s first known multi-tool,” which has a serrated edge on one side and two sharper edges on the others, one of which Briggs describes as curved like a spoon. “It’s a very cool piece of technology,” she says. “[It’s] got three different sides that you can use to do different things.” And, she adds, “it’s the oldest thing yet found in North America.”

All of which is interesting, in part, because it confirms that tribal stories may accurately deliver history for a lot more than the 7,700 years since the Mt. Mazama eruption.

“A lot of the stories have references to giant animals,” Lewis says. “[They] seem to be a memory of being among megafauna.”  Other stories reference massive floods that filled the valleys to the north of Rimrock Draw nearly to the mountaintops.

It’s bigger than any flood imaginable

These, like the stories of Mt. Mazama, would have seemed fanciful until the 1920s, when a geologist named J Harlan Bretz spent eight summers scouring the inland Pacific Northwest. Even then, it was decades until geologists realized that periodic releases from the northernmost Ice Age lakes might have produced floods that would have made Noah blanch.

No, they didn’t top out the mountains. But they did produce walls of water 200 meters high. And how else could you describe that? Lewis asks. “It’s bigger than any flood imaginable,” he says. “It’s going to fill up the valley to the tops of the mountains, right?”

Briggs agrees. “It does well to remember Indigenous knowledge when we are doing Western science,” she says. “Native American people have been telling us they’ve been here since time immemorial.”

Which leads to the biggest question of all: when did people first reach the Americas?

Until the new findings at Rimrock Draw, the earliest known archaeological site was at Cooper’s Ferry, 500 hundred kilometers away in Idaho. But old as it was, it could only be dated back to about 16,000 years ago.

Rimrock Draw pushed this back by nearly 15 percent. And if a single find can do that, what remains to be discovered?

American archeologists have long presumed that the first people came across from Asia, sometime after 37,500 years ago, when sea levels dropped enough to create a land bridge across the Bering Sea from Siberia to Alaska. One theory is that once they got across they lived in Alaska until the glaciers retreated enough to create an ice-free corridor between the western and eastern Canadian ice sheets. It’s a fine idea, but geophysical studies suggest that this migration route didn’t open up until at least 4,500 years or so before people were happily camping at Rimrock Draw.

Another theory is that they came across the land bridge then migrated down the coast in canoes. It’s a perfectly fine theory, and might be true. But it raises an important question.

People have been in Australia for at least 50,000 to 60,000 years. And they most emphatically didn’t get there by way of a handy land bridge. “The only way they could have gotten there was by boat,” Lewis says.

And if they could do that, why couldn’t others have gotten across the much narrower strait between Siberia and Alaska, tens of thousands of years before the land bridge would have allowed them to do it on foot?
Bottom line: anyone who thinks 18,250 years ago might represent the dawn of North American settlement might have a big surprise coming. There’s really no reason it might not go a lot farther back than that.