By David Malakoff |
For more than a century, archaeologists have debated why ancient Native Americans built the stout stone towers that sit high above the floor of Nine Mile Canyon, a serpentine gulch in eastern Utah. They agree the circular structures were built more than 500 years ago by people belonging to the Fremont culture, who also created remarkable rock art on the canyon’s sandstone walls. But there was little consensus on how the Fremont people used the towers. Some scholars believe they were watchtowers positioned to warn of raiders. Others think they were refuges where residents could hide when threatened. But “the problem was that, historically, there was no really rigorous way to test these explanations, and see which was best supported by the evidence,” said archaeologist Weston McCool of the University of California, Santa Barbara.
That has changed in recent years. Drawing on an array of technological and intellectual innovations—including brawnier computers and software, abundant high-resolution mapping data, and the creative use of techniques originally developed by ecologists to explain wildlife behavior and by military engineers to position artillery—archaeologists can now visualize past landscapes and better understand how ancient people saw and used them. In essence, researchers now have “a suite of geospatial tools and methods that allow us to create a kind of archaeological Google Maps, which we can use to travel back in time,” said archaeologist Mark McCoy of Southern Methodist University, who last year published Maps for Time Travelers, a book about geospatial archaeology.
At Nine Mile Canyon, for example, researchers used these tools to construct a detailed, three-dimensional digital model of the Fremont-era landscape. They then used that model to recreate how ancient raiding parties would have stormed through the canyon, and to calculate what people perched in the towers could see, helping reveal the likely purpose of the structures.
University of New Hampshire students map a cache pit in the field in northern Michigan. Geospatial tools like LiDAR, combined with ecological modeling, has greatly increased archaeologists’ ability to find these subtle features in wooded settings. | Credit: Meghan Howey
An illustration of two potential travel routes in southern Ohio that may have connected Sandy Springs, a Paleo-Indian site, and the Upper Mercer/Vanport chert outcrops. These travel routes were generated using a Least Cost Analysis (LCA) approach that calculates the most cost-effective route between two positions based on a ruggedness factor of the surrounding landscape. LCA analysis suggested that the more energy-efficient route was through the lower Scioto Valley. Archaeological data, however, indicated that Paleo-Indians preferred taking a route to the west, though it added at least eight travel hours to their journey. | Credit: Matthew Purtill
Geospatial techniques have led researchers to conclude that towers like this one at Nine Mile Canyon served as refuges. | Credit: Dennis Udink