Students explore "ancient" site with aid of modern navigation, pictures
Students explore "ancient" site with aid of modern navigation, pictures
April 24, 1998: Long ago, it is said, a sacred site was hacked out of the wilderness by a special worker class using hand tools. Then, great birds descended from the sky, bringing strangely garbed people who used special branches to return small white balls into the underworld.
Now abandoned, this archaeological puzzle is left to a couple of scientists and some high school students who on Earth Day (April 22) have come here asking, "Where is the first tee?"
Right: "Where is the first tee?" is the question as the students learn what Tom Sever (center) has worked with for years: Nature can make human artifacts invisible even when you are standing on them.
OK. It was a golf course built around a small airstrip in the mid-1930s in DeSoto State Park near Fort Payne, Alabama. But because the original map is available, it is a perfect classroom for teaching the basics of using satellites to map natural resources and even to study our own history.
"Let's use the first tee as our first objective and set your heading," Gregory Cox instructed Philip Showers, a 12th grade student at the New Century Technology Demonstration High School in Huntsville, Ala.
Showers and classmate Jamie Allen are two of four students taking the school's remote sensing course sponsored by NASA's Marshall Space Flight Center. Cox, who is on loan from the University of Alabama in Huntsville to the Education Office at NASA's Marshall Space Flight Center. He is the director of the Global Learning and Observations to Benefit the Environment (GLOBE) program in Alabama and works with the Global Hydrology and Climate Center.
"It is expansive," Showers said of the program at his high school. He and the other three students (two could not make this trip) are working on a virtual-reality model of an ancient Mayan city to put on the Internet.
"We've taken a map of Calakmul and taken nine of the central buildings and rendered them in virtual-reality markup language (VRML)," Showers said, so anyone on the Internet can go to that site and wander around an ancient Mayan city."
Allen has researched the city through the Internet, finding images and backgrounds to enhance the model.
After graduation this year, Showers plans to attend Auburn University and become a chemical engineer. Allen is headed for the University of Virginia and a career in aerospace engineering.
"They've been meeting through the year and learning about Landsat and remote sensing," said science teacher Jeanette Conway. "They've learned a lot about the Mayan culture and the work that Tom is doing."
Tom is Tom Sever, a NASA archaeologist who has pioneered many applications of satellite images to archaeology, and who has explored ancient Mayan sites in Guatemala.
|Composite weather satellite images form a map of Alabama (left) which show the general locations of Huntsville and DeSoto State Park. Landsat thematic mapper image shows the location of Desoto State Park and, circled within it, the runways of the golf course. The highlighted box alters the colors in the image to bring up details - like the runways. Click on images for more detail.|
Cox has been using this part of Alabama's DeSoto State Park as an open classroom for several years. The Civilian Conservation Corps, a massive public works project that employed thousands of young Americans during the Great Depression, developed it in the mid-1930s. Using hand tools, they cleared a flat area covering 1100 acres, and built an airfield with three grassy landing strips surrounded by a 9-hole golf course.
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Cox said the expectation was that the well-heeled could fly in for a few days of golf away from it all. But after only a few years of use, the area was abandoned for reasons unknown. Nature slowly reclaimed the area. The fly-in golf course now is part of a wilderness area for campers and hikers.
Cox said that some archeology work actually goes on here. Ken Thomas, the DeSoto Park naturalist, is an amateur archaeologist who periodically turns up fragments of hand tools and other artifacts left by the CCC workers when they built the park.
For now, though, the team's chief concern is recovering part of the golf course as a field exercise to cement lessons in how remote sensing works.
The team is starting with an unfair advantage, though. They have an accurate map made by surveyors when the golf course and airfield were laid out. Archaeologists often have only oral legends to use as their starting points.
Because the trek through the woods capped several weeks of studying aerial and satellite images, Cox first had the team sit down in a picnic shelter - once the golf pro shop and air tower - and review Landsat and other images they had been studying (left).
Turning to the map of the golf course, Cox and the students selected their first objective - the first tee - and set their headings.
Here they have another advantage, Global Positioning System (GPS) receivers, one of the most valuable items to be added to the archaeologist's toolbox.
"Right out of the box, these GPS units are really accurate, down to about 50 feet," Cox said. That can be improved to about 30 feet by letting a unit sit and average its readings for several minutes. Military GPS receivers can provide accuracy down to a fraction of a centimeter.
|Before setting out through the woods, Cox describes how the GPS receivers (right) work and how a more accurate position can be obtained by taking an average over several minutes. Click the images for more detail.|
With the maps checked, Cox took the students to a rock where he had set up three different GPS receivers. Although only a few years old, they showed great differences in capability, ranging from a unit that just simply tells your position to one that shows a roadmap, your direction, speed, and other details.
"You can't walk through the water hazard," Cox joked, and then led them around the pond to where they could resume their trek. A few minutes later, the GPS display indicated that they had gone far enough.
"This was the first tee," he said as they stood atop a slightly elevated area with a tree in the middle. What once had been a cleared, manicured lawn now was a stand of 60-year-old pine trees and modest undergrowth.
Pine trees are secessional growth, the first trees in as land is ceded to nature, "so this area had been developed," Cox said.
This was also near the intersection of two runways.
"So you can see in your mind one runway went in that direction, the other went that way, and the third cut diagonally across over there," he said.
The next objective was the second tee, about 2,500 feet away.
"It could have been in this area," Cox said as the team looked for signs of the tee. "If you think of this as cleared and leveled, it could have been just a flag in the ground."
"Notice the pines, and right along here are the hardwoods," Cox said. "That's the area that was cleared. This was not cleared." The difference is a subtle one that most people would miss unless they knew what to look for. After another 100 years, the hardwoods will have moved in, and the difference will be blurred even more.
"What I really wanted you to note was the change in vegetation and why there's a change in vegetation," Cox continued. "If this had been undisturbed, it would be all hardwoods, hickory and oak. Instead, we have a lot of pines. That's what you're seeing when you look at the satellite images and get color variations in the vegetation."
"You've just seen what we do when we find the Mayan causeways in Guatemala," Sever explained. "You see a small change in vegetation and then you have to excavate to confirm it." The causeways are important because they ultimately lead to the cities and the temples at their centers.
During a lunch break at Little River Canyon National Preserve, Cox shows Showers and Allen how to locate their position on a Landsat image of the area. Sever watches from behind.
Dirt in the causeways is more compacted and thus has different drainage patterns that in turn affect how plants grow, even down to making trees over the causeways slightly taller than others, an effect seen only for a few minutes at sunrise.
While the tropical rain forest and the Alabama woods are completely different, "it's the same phenomenon you see here," Sever told the students. "This is exactly what we do."
Showers and Allen set another heading and a few minutes later they and
Cox led the team out of the woods to the picnic clearing where the trek
had begun. It may yet lead them to other destinations.
Other stories using GPS in archaeology:
NASA Helps Find Mayan City, April 7, 1997
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