Monday, May 20, 2024

A Pre-Clovis Site on Chesapeake Bay

WaPoo, Ancient Chesapeake site challenges timeline of humans in the Americas 
“I was a weirdo kid,” he recalled. He trained as a geologist, and it was geology that initially attracted Lowery to study Parsons Island.

In 2010, he published an article in Quaternary Science Reviews describing layers of windblown silt deposited between 13,000 and 41,000 years ago at Miles Point in eastern Maryland. But the geological record is like reading the CliffsNotes version of a book, and he was frustrated by an “unconformity” in the sediment layers where thousands of years were missing, like someone had ripped out those chapters.

Lowery and a colleague were prowling around in a boat, looking for a spot that might fill in the blanks, when they spotted a black streak of sediment rising up out of the bay. They pulled up to Parsons Island and thought they had found “the Rosetta stone” to decode the geology.

Parsons is a 78-acre island less than a mile offshore that is privately owned by the Corckran family, which uses it as a family retreat. With the Corckrans’ permission, Lowery and colleagues began to visit regularly. The bluff layers preserved a remarkably intact geologic timeline going back more than 40,000 years.

Then, one morning in August 2013, the team discovered a leaf-shaped prehistoric stone tool jutting out of this crumbling wall. They knew from the work they’d already done that it was probably quite old.

On a recent visit to the island, geoarchaeologist Daniel Wagner demonstrated why. He stepped back to scan the cliff, then tapped a narrow spade into a light tan sediment layer just above his head. That, he said, is the geologic “chapter” where they’d expect to find Clovis artifacts. Lower layers were set down before Clovis.

The palm-size tool Lowery and his colleague found came out of the dark sediment layer near their knees.

The scientists used two methods to date the sediment around the artifact, both showing it was more than 20,000 years old. They scoured the beach on 93 visits and conducted a formal, top-down excavation, collecting the 286 artifacts. They sent out sediment to labs that specialize in studying ancient pollen and microfossils called phytoliths to help reconstruct the ecosystem at the time.

Back then, this region wouldn’t have been a coastline. The sediment the tools are embedded in dates to the “last glacial maximum” — the scientific term for the most recent coldest period of the Ice Age. In the final analysis, Lowery thinks the artifacts may have been transported downslope before they were buried, making them between 15,000 and 20,500 years old.

At the time of the last glacial maximum there would have been no Chesapeake Bay, merely the Susquehanna River running down what is now the main channel of Chesapeake, out across the continental shelf and into the Atlantic. Parsons Island, would have been a fair distance back from the river, although  there would have likely been nearby streams. 

“This was a swale, where water was collecting,” Lowery said, envisioning the ancient landscape. “You’ve got a dune. It’s got sedges and small trees on it that are windblown and all contorted, and then behind it you’ve got a little pond.”

That pond may have attracted prehistoric bison, musk oxen and llamas, whose fossilized molars he’s found scattered on the island shore. And it may have been what attracted the mysterious people who left behind a cache of stone tools.

The Clovis-first hypothesis has been pretty well busted for quite a while now, but evidence of a Pre-Clovis community in the Bay region certainly expands they're range. It's still an open question whether the Pre-Clovis population had much genetic contribution to the Native American population present when Europeans arrived. Did they suffer an extinction, or near extinction event at the Younger Dryas? We're they largely conquered and wiped out by the more recent Native Americans after they crossed the Bering Straight, or merely intermingled in the population? 

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