Mound Key (USA): Archaeologists use old and new technology

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With a soft whir, four propellers lifted the DJIPhantom 2 drone smoothly off the ground.

Its mission was not to gather intelligence on enemies foreign or domestic, but rather to collect photographic data on an archaeological excavation at Mound Key in Estero Bay.

Mound Key was probably the Calusa Indian capital when Ponce de Leon arrived inSouthwest Florida in 1513 (at the time, the Calusa dominated South Florida, demanding tribute from as far away as Cape Canaveral and the Keys); it was likely the site of the first Jesuit mission in the New World.

Researchers from the University of Florida and the University of Georgia, with the help of FGCU students, are trying to determine the location the mission and the island's main Calusa structure.

Funding from the project is from the National Geographic Society, the University of Georgia and The Knight Foundation for Florida Archaeology.

Last year, the researchers used ground-penetrating radar to explore the site; this year they've added the drone, which shoots photographs of an excavation pit every time the excavation team digs down to a new level (a level is about 4 inches), said Brandon Ritchison, a University of Georgia doctoral student.

"That way, we can create a data set, because every time we go down a level, the soil we've excavated is gone: Archaeology is inherently a destructive science," Ritchison said. "So, by taking these top-down photos, which are of higher quality than we get when we're trying to stand on buckets, we get a better record for research, and we become better stewards of the past."

In 1566, Spaniards met with the Calusa paramount Chief Calos and reported a structure that was large enough for 2,000 people to stand without being crowded.

Using the University of Georgia's ground-penetrating radar, which uses radio waves to detect buried material, researchers identified anomalies last year that might be the remains of walls and posts from the Calusa structure on Mound 1, which rises about 30 feet above the bay.

The anomalies suggest an structure about 100 feet across, said Bill Marquardt, curator in archaeology of the Florida Museum of Natural History.

But ground-penetrating radar only shows what might be remains of the structure; to prove the structure was there, the archaeologists must actually dig, which they started doing last week and will continue to do until June 2.

So far, they've discovered post molds (dark areas in the sediment where poles once stood) and what might have been a wall trench (rather than dig individual post holes, the Calusa probably dug trenches, into which they placed vertical posts to support walls, and then filled the trench with shells).

"The Calusa were a powerful people," Marquardt said. "This would have been quite an impressive building, and the Spanish described it in quite a bit of detail.

"Even if the Spanish were exaggerating about its being able to hold 2,000 people, we know it was a substantial wood-and thatch-building."

Researchers are also taking core samples down to about 12 feet into the mound.

The cores contain layers of material deposited on the mound over the centuries; it's a quicker way to see how and when the mounds were built, but it gives less information than an excavation.


Melissa Ayvaz, of the University of Florida, works on excavating Calusa artifacts on Mound Key on Thursday.(Photo: Jack Hardman/The News-Press, Jack Hardman/The News-Press)

"It's instant gratification: It would take months to dig that deep," said Victor Thompson, assistant professor of anthropology at the University of Georgia. "It's minimally invasive, equivalent to a small burrowing animal, of which there are many here."

Meanwhile, eight FGCU students were digging on Mound 2, which rises about 20 feet above the bay and is the possible site of the mission, and were finding plenty of Spanish artifacts, including olive jar fragments, painted ceramics, glass beads and a small amulet.

"You can't learn this in a classroom," said Alison Elgart, an FGCU professor of anthropology. "This is one of the most amazing sites in Florida; you can read about it, but there's nothing like getting in the dirt."

Covered with dirt, FGCU senior anthropology major Lauren Sanchez was obviously excited to be working at the site.

"We're doing a lot more than we thought we'd do: They're letting us excavate, and we're finding a lot of cool things," she said. "I've never done this before; it's hard work, but we want to do a good job and not look at it as hard work. But, at the end of the day, I'm happy to go home and take a shower."