AK: Ancient Shorelines
Most of us like to know something about our family history. And we might want to get some idea of who was here before us.
In Southeast Alaska, scientists and university students are looking for new evidence of early human habitation — and they’re finding it. They first have to figure out where the shoreline used to be.
“It’s like a sandy loam that’s got a lot of organic in it,” David D’Amore says, digging into a hole on the University of Alaska Southeast’s Juneau campus.
He’s looking for evidence that this spot –about 75 feet above sea level – was once an ocean shore.
“Digging sound, I can kind of see it now. This looks like it’s organic, over that beach, and then you hit organic again. Oh you do? How interesting,” D’Amore said.
D’Amore is a soils expert with the U.S. Forest Service’s Pacific Northwest Research Station. He’s one of the scientists working with university students to map Juneau‘s ancient shorelines.
They’re hard to find, because of the region’s ever-changing geography.
The weight of huge glaciers depresses the Earth’s crust. Their forward movement creates bulges of land. Their melting allows the surface to rise. And then, there’s plate tectonics.
Early residents – Tlingit Indians or their predecessors – lived along those shorelines. So finding their location, sometimes hundreds of feet above today’s sea level, can lead to new discoveries.
“We need one of those three-gallon buckets,” Dan Monteith, an anthropology professor at the university, said. He’s scooping water out of another hole, where he hopes to find something interesting. “Just emptying.”
“We’re going around, following up old river drainages or cut banks looking for evidence of old, ancient, raised marine beaches.”
They’ve already found some. Monteith walks up a small creek to an eroded bank. There, sticking out of the soil, are small, dirty-white seashells.
“By collecting shells and other things from those areas, then we can radio carbon-date those and get kind of a fixed point of when that was a beach at different points of time,” Monteith said.
The technique was developed on Prince of Wales Island.
Forest Service Geologist Jim Baichtal says you can make an educated guess at where early residents used to live.
“Just as you and I today would camp within 2-3 feet of high tide, so would folks in the past,” Baichtal said. “And if you had food and you had good moorage, that’s the kind of places we would camp.”
Baichtal and other scientists began their effort about four years ago. They headed up an estuary and into the forest to where waves lapped the shore thousands of years earlier.
“And we dug down about 50 centimeters and dug into the top of over a meter of charcoal and tools and other things that were left there by the inhabitants of that place,” he said.
Radiocarbon-dating showed the items to be around 10,000 calendar years old.
Baichtal says he and other scientists tried the technique on more than 75 Prince of Wales Island sites. About a dozen dated to around that time, showing Southeast’s first residents were well-established by then.
“It had been thought in the past that maybe there weren’t large populations here that early,” Baichtal said. “But it was because we never knew where to look. And this is giving us a whole different way of where to look and what to look for.”
Back at the university, Monteith and his students record GPS coordinates for each hole they’ve dug.
“Did you guys get lat and longitude on any other test bits we got? The Auke Bay school?” Monteith said.
The group has dug in other areas of Juneau. It’s also inventoried known tribal sites in a bay north of town.
Student Bernadine DeAsis says that helped her learn some of her own history.
“That was really important for me to know the history and the background to get a perspective of where the Tlingits were in this area, because I’m Tlingit myself,” DeAsis said.
Schoenfeld: “Are you hoping with the shellbed search to find some evidence of where people use to live?”
DeAsis: “Yes we are. We know for sure that they’ve been in this area, so it’s kind of like a treasure hunt for me.”
The effort will continue for many years, expanding to other parts of the region in hopes of creating a shoreline map that will lead to more discoveries.