AMY BENNETT WILLIAMS

AWILLIAMS@NEWS-PRESS.COM

There's a reason you won't catch most local fishermen using anything but synthetic nets: Saltwater and subtropics are brutal on natural fiber, rotting it to frayed pulp in one scant season.

Which is what makes a bunch of newly filled zip-lock bags exciting to an archaeological team that's spent the last couple weeks painstakingly digging on Pine Island: They're full of thousand-year-old Calusa Indian rope, net and twine, among other finds.

No one has seen remnants of ancient daily life like this since the 1800s, when a Smithsonian expedition led by pioneering anthropologist Frank Hamilton Cushing unearthed more than 1,000 remarkably well-preserved artifacts, including the celebrated Key Marco cat near Marco Island.

Some of the more extraordinary things to emerge from the Pine Island pit are pieces of netting, complete with tied-on weights. Archaeologist Bill Marquardt, curator in South Florida archaeology and ethnography at the Florida Museum of Natural History and director of Pineland's Randell Research Center, points to a bagged white clam with a hole knocked in it, threaded with knotted twine.

Mound Key Calusa site focus of marine science students

"These ark shells they used to weight down their gill nets and their seine nets, with the knots still tied — that’s the kind of preservation we’re getting. In addition to that, we’re getting pieces of wood you can still see the working marks on, and seeds such as squash seeds that will help us figure out what kinds of plants they were using."

Most clues about the Calusa, who'd largely disappeared by the 1700s, come from the remains of their civilization buried in shells and mud of the huge mounds for which they're known. Such remnants add to scientists' ongoing understanding of the people who called Southwest Florida home for thousands of years before Europeans arrived in the 1500s, as do the writings of the Spanish explorers and evangelists who tried fruitlessly to win them over.

Hardy survivors, the Calusa developed a complex empire that exerted control over much of the peninsula. They built thatched huts, dug canals and crafted tools, utensils and art from bones, shells, clay and wood. Their culture will be highlighted at Saturday's Calusa Heritage Day at the research center.

Though scientists and volunteers regularly dig Calusa sites in and around Pineland, once home to the second-largest Calusa town, most of the excavations are high above the water table.

Hard things like shell, bone and pottery usually hold up in such places, but softer organic material like wood and plant fiber don't survive millennia when exposed to sun and air. If they're safely covered in liquid or mud, however, they can be preserved.

That's what happened at the Pineland site the University of Florida team just finished excavating, after a preliminary dig in 2015. The artifacts there were left (or dropped or lost) at a time when sea level was relatively low.

"Then it rose pretty quickly," said Marquardt, who led the excavation. "We think it rose quickly enough that it sealed in this deposit, so it created an anaerobic situation and preserved the material. ... (When) we dug down here in 2015, we found that this midden goes well below water table, well below sea level. And it kept on going."

Portable pumps made the work conducted by the team of scientists and volunteers possible; otherwise the hole would quickly have filled with groundwater. The 2015 dig happened in a hurry, when the site's owners agreed to allow the team to take a look before a new septic system was installed.

Quick as the initial look was, "We knew that there was a very special deposit there," said Karen Jo Walker, the museum's collections manager for South Florida archaeology and ethnography.

"But we were not prepared to do an underwater excavation, and we only had four or five days, so we decided to come back, take a couple of weeks and do it right," Marquardt said.

He and Walker are glad they did, as is paleoethnobotanist and MacArthur Fellow Lee Newsom, a visiting professor of anthropology at Flagler College who joined them on the dig. Newsom studies ancient plant remains, and for years has collaborated on work at Pineland.

"When we excavated down, the kind of preservation we’re getting is as good as anything Frank Cushing got at Key Marco in 1896," Marquardt said.

But the story the site tells goes beyond human history; it records what was happening on the planet as well.

"Sure we like to find artifacts like anybody else does, but sometimes the things we find are so tiny people probably wouldn’t pay them much attention, but they’re exciting to us," Marquardt said, holding up another Zip-Lock. "In this little bag here, I have a shell you can hardly see, a beautiful truncatella. It’s not a marine snail. It lives, dies and reproduces on the wrack (high-tide) line. Finding these guys here tells us where the shoreline was a thousand years ago," he said.

"So, yes, artifacts are cool, but it’s all kind of a big puzzle we’re trying to put together."

If you go

Calusa Heritage Day is a great introduction (or reintroduction) to the Randell Research Center and Pineland's archaeology. It's from 10 a.m.-4 p.m. Saturday at the center, 13810 Waterfront Drive in Pineland. The $5 admission (free to kids younger than 12), gets you into the the site, which includes the Calusa Heritage Trail, meandering through the site's mounds, canal, native plant communities and stunning water vistas. Activities include presentations, tours, exhibitions of flint-knapping and basket-making, kids' crafts, vendors, food and much more. Call 239-283-2062; online: flmnh.ufl.edu/calendar/grid/calusa-heritage-day/?eID=2732