A group of school students visits the
Washington University excavations
of Mound A at Poverty Point.
CREDIT: WUSTL Photo
Ancient Earthwork Was Built with Surprising Speed
Jan 31, 2013 | Megan Gannon | Live Science
The enormous earthen monument Poverty Point, built on a Mississippi
River bayou some 3,200 years ago, is an impressive feat of engineering.
Hunter-gatherers moved more than 26.5 million cubic feet (750,000 cubic
meters) of dirt to create concentric ridges and several large mounds in
what is today northern Louisiana.
Now researchers say one of the most impressive earthworks at the site
likely took shape in fewer than 90 days, built by thousands of Native
American laborers using a "bucket brigade" system.
Archaeologists excavating parts of Poverty Point, which is now in the
running to become a UNESCO World Heritage Site, analyzed core samplings
and sediments from one of the massive earthen features known as Mound A.
Curiously, they found no traces of rainfall or erosion during the
construction phase of the mound.
"We're talking about an area of northern Louisiana that now tends to
receive a great deal of rainfall," said researcher T.R. Kidder, an
anthropology professor at Washington University in St. Louis. "Even in a
very dry year, it would seem very unlikely that this location could go
more than 90 days without experiencing some significant level of
rainfall. Yet, the soil in these mounds shows no sign of erosion taking
place during the construction period. There is no evidence from the
region of an epic drought at this time, either."
Mound A, which stretches across 538,000 square feet (50,000 square m)
at its base and rises 72 feet (22 m) above the river, is thought to be
the last addition to Poverty Point's altered landscape. If it were built
today, it would take a 10-wheel dump truck more than 30,000 loads to
move the estimated 8.4 million cubic feet (238,500 cubic m) of dirt that
make up the mound, Kidder and his colleagues said. But hunter-gatherers
likely did it with bushel baskets.
"The Poverty Point mounds were built by people who had no access to
domesticated draft animals, no wheelbarrows, no sophisticated tools for
moving earth," Kidder explained in a statement. "It's likely that these
mounds were built using a simple 'bucket brigade' system, with thousands
of people passing soil along from one to another using some form of
crude container, such as a woven basket, a hide sack or a wooden
platter."
The researchers believe to complete such a feat in such a short amount
of time would have required about 3,000 laborers. This suggests that as
many as 9,000 archaic Native Americans might have flocked to Poverty
Point for the huge construction project, assuming that many of the
workers were accompanied by their wives and children, the team said.
"Given that a band of 25-30 people is considered quite large for most hunter-gatherer
communities, it's truly amazing that this ancient society could bring
together a group of nearly 10,000 people, find some way to feed them and
get this mound built in a matter of months," Kidder said.
"These results contradict the popular notion that pre-agricultural
people were socially, politically, and economically simple and unable to
organize themselves into large groups that could build elaborate
architecture or engage in so-called complex social behavior."
Poverty Point was recently nominated to become a UNESCO World Heritage Site
because of its cultural significance. Artifacts excavated at the site
come from as far away as the Ohio and Tennessee river valleys and the
Appalachians of Alabama and Georgia, indicating the Poverty Point
civilization was heavily involved in trade, the Louisiana Office of
Cultural Development's Division of Archaeology noted in its UNESCO
application.
The new research was detailed online last month in the journal Geoarchaeology.