Satellites unveil 2,000-year-old trails
Researchers at the University of Colorado at Boulder (CU-Boulder) and at NASA have used satellites to track the movements of people living in the Arenal region of Costa Rica more than 2,000 years ago. They've also used video-game software to virtually 'fly' above the footpaths taken by Central Americans between small villages and cemeteries. It's a fascinating story because Arenal Volcano is still very active and that the people who lived there didn't disappear as highly structured societies like the Maya and Aztec. And people living today in the Arenal region are certainly friendlier than your neighbors.
This research has been led by CU-Boulder Professor Payson Sheets, of the Center to Advance Research and Teaching in the Social Sciences (CARTSS) and who's focused on "Investigating The Origins of Monumentality in Ancient Costa Rica."
Before going further, here is a picture of Arenal Volcano when it's quiet. (Credit: Payson Sheets, CU-Boulder)
But sometimes this active volcano erupts, as you can see below (Credit: Michael Smith, Cocorí, Costa Rica). Here are some other photos from Michael Smith on this Arenal Volcano page.
Now, let's look at what the researchers have found.
The researchers have traced one processional path from a village on the Caribbean side of northern Costa Rica over the Continental Divide to a cemetery about 10 miles away using infrared satellite images that indicated characteristic signatures of plant growth, he said. The eroded footpaths -- some virtually invisible to observers on the ground -- collect water that stimulates increased root growth in the vegetation that appears in the images as reddish lines, said Sheets.
"This project has been a huge surprise," said Sheets. "Modern technology has allowed for the discovery and study of 2,000-year-old footpaths in the tropics where the ground is covered by thick vegetation and multiple layers of ash from prehistoric volcanic eruptions."
But exactly what kind of technology was used? Sheets collaborated with Tom Sever, NASA's only archeologist, to use NASA satellites. By the way, you should read "The Rise and Fall of the Mayan Empire" (NASA, November 15, 2004) to discover what an archeologist can do for NASA.
Images of the footpaths were made by various NASA satellites and aircraft and by a commercial satellite known as IKONOS. Built by Space Imaging of Denver, IKONOS has a resolution of less than one meter and is equipped with infrared sensors that can peer through deep jungle foliage. The team used computer software known as TerraBuilder, [a 3-D terrain construction application created by Skyline Software Systems,] and provided free to the researchers, Sheets said.
Please read the whole CU-Boulder news release to learn more about this project: it's written in plain English!!!
And for more information about Payson Sheets previous work, you can read earlier news releases from CU Boulder, "Prehistoric human footpaths lure archaeologists back to Costa Rica" (May 20, 2002) or "Prehistoric footpaths in Costa Rica indicate intimate ties with villages, cemeteries" (October 7, 2003).
Finally, if you want to see Arenal Volcano, a visit you'll enjoy and that I highly recommend, you can start by checking this page provided by Costa Rica National Parks.
Sources: University of Colorado at Boulder news release, January 2, 2007; and various websites
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