Friday, February 18, 2011

As you may know, FPAN’s mission has three basic tenets: to engage the public in archaeology outreach and education, to assist local and county governments, and to support Florida’s Division of Historical Resources. The Northeast Region uses a variety of strategies to meet each of these aims, and we always get excited when an activity accomplishes more than one of them.

With help, nearly anyone can operate GPR equipment.

Ground Penetrating Radar (GPR) is one such tool. If you’ve hung around the FPAN Northeast ladies, you already know that Sarah and I think GPR is, in some ways, a public archaeologist’s dream. When we take the machine out, we use volunteers to set up our grids and can let virtually any member of the public operate the equipment. It allows us to change the focus from “finding treasure,” which is not what archaeologists seek, to “learning about people of the past.”

I could tell you about it all day long, but I think it’s more fun to show you. Here are some examples from our most recent GPR efforts in St. Augustine:

The Plaza

St. Augustine's City Archaeologist Carl Halbirt excavates a test unit in the Plaza.

At this site we engaged the public while assisting the City Archaeologist, Carl Halbirt. He recently excavated a test unit in the southeast end of the Plaza and found evidence of a large post. He asked us to do GPR to see if we could detect other posts nearby. If we could, it might help him figure out which direction the structure went, and how large it was.

For all the projects this time, we used 3D GPR. To do this we had to lay out a grid and run the GPR over the grid several times north-south, then east-west. We set up two grids, one north of Carl's test unit and one to the south. We didn’t have any volunteers signed up to help us that day, but it didn’t matter. We talked to 30 people while we were out there, and several of them took turns operating the machine.

A local man tries his hand at GPR.

The most common question people ask is, “Are you looking for treasure?” Usually, I groan inwardly when I hear that question. Aside from the notion that we study dinosaurs, that’s probably the greatest misconception archaeologists face. As archaeologists, we study people and cultures of the past. Though some artifacts are pretty spectacular, more often than not we piece together what life was like by observing some pretty mundane stuff—itty bitty ceramic fragments, rusty nails, and animal bones for instance.

An archaeologist's treasure: animal bones provide a
wealth of knowledge about diet.

Another treasure: ceramics can inform the date of a site
and offer clues to financial and social status.

With GPR, I was excited to field that question. It is a terrific teachable moment. Why? We weren’t looking for treasure, or any artifacts at all!  We were just looking for soil of a different density than the “normal” ground. The posts to that structure rotted away long ago, changing what the dirt was like. GPR could help identify these locations.

Fountain of Youth

Carl and volunteer Janet excavate a posthole in the middle
of an older shell foundation at the Fountain of Youth.

Next we partnered with City Archaeology, the Fountain of Youth, and the University of Florida. We went to the Fountain of Youth Archaeology Park, where Halbirt excavated last fall. Gifford Waters of the University of Florida joined us too. He came to tie the maps from their UF's field investigations to our GPR work.

When City Archaeology dug there in the fall, they uncovered the foundation for a mission-era structure and a shell midden predating the mission. We set up a grid just north of the area of investigation to see if we could pick up those features.

We map each GPR site to keep track of any objects that may interfere with pushing the machine (for example, the tree near Gifford's forefinger).  THIS is the kind of map you get when you accidentally hide the forms.

Nombre de Dios

Next, Gifford and several volunteers met us at Nombre de Dios. Last year we took a 3D GPR grid of the area just south of the chapel, and we followed up this time by exploring an area further south. In one of these areas may be an earlier mission structure. UF has studied this site for many years. Paired with the Fountain of Youth, they make what was almost certainly the landing site and earliest encampment of Pedro Menendez.

GPR at Nombre de Dios

We didn’t see quite as many people as we did at the Plaza, but we talked to a few. As always at these St. Augustine stops, some were local, and some were visiting. The “Longest Distance Traveled to Witness GPR” Award that day went to a couple from Michigan.

Colonial  Spanish Quarter

The last day of our GPR adventures, we went to a city-owned site—a large open area that makes up part of the Colonial Spanish Quarter. Carl and his crew had been digging just to the east of the GPR site. We planned to find out if his site continued to the area where we laid out our grid. Gifford again joined us (as Kathy Deagan, formerly of UF, had excavated there several years ago), and we had a handful of volunteers to help us out.

Volunteers lay out the grid and operate GPR equipment while I bask in the sunlight, snapping pictures.

Sadly, this area wasn’t open to the public, but we did enjoy visits from some of the Colonial Spanish Quarter staff.

Deleted scene from "Bill & Ted's Excellent Adventure?"  No! 
Colonial Spanish Quarter staffer & City Archaeology Volunteer Lynn collects GPR data.

GPR is a terrific tool for getting an idea of what’s in the ground without (or before) excavating, but only digging can confirm our predictions. We carry out these types of investigations for different reasons, too—in some sites, we don’t want to dig—we simply want to find out whether it’s likely that archaeological features are in the area. For instance, when we did GPR in historic cemeteries during prior investigations, we wanted to determine whether unmarked burials were present. If they were, we didn’t want to disturb them.

Other times, we hope to provide direction for future investigations. For instance in the Plaza—if we found evidence that there may be posts to the south of Carl’s unit but not to the north, he probably wouldn’t dig north of his unit. It would save him the time of having to open up ground that is unlikely to contribute to his investigation.

We don't have results yet for the grids we explored, but our conclusions about using GPR with the public are as strong as ever.  We had a great time sharing with the people we met, and loved letting them try their hands at real archaeology.  Next time you see us pushing this thing around your neighborhood, feel free to come out and play!

~~Amber J.

2 Responses so far.

  1. Deleted scenes from Bill and Ted's...hilarious

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