Airborne Archaeologist Challenges Myth of a Pristine Wilderness
Kay
by Ted Mann -- In the office of a typical archaeologist, you would
expect to find things like stone tools, pottery fragments, and maybe
even a few Wooly Mammoth bones. But Clark Erickson is no typical
archaeologist. Oversize rolls of aerial photographs are stacked into
tubular pyramids on a desk and worktable in his University Museum
office. They fill up file cabinets and populate a storage room. At
last count, he had about 700 giant aerial and satellite images, almost
all of them picturing some region of the Amazon.
He rolls out a 1958 U.S. Air Force photo of a Bolivian savannah. Even
with the vast acreage blown up to movie-poster size, the details are
as impenetrable as braille to the sighted. "See that," he says,
pointing to a line running across the landscape. "Anything that's
straight, it's not natural." With a finger, he traces a symmetrical
block of toothpick shapes. "These are raised fields. See, you can pick
out the linear patterns." With Erickson's narration, more and more
geometric designs pop off the glossy print settlement mounds, fish
weirs, irrigation canals, roads. The photo begins to look like a
prehistoric engineering blueprint. Unlike most archaeologists,
Erickson doesn't begin his research in excavated holes; he starts in
the sky, reading the landscape for markers of vanished civilizations.
For the past decade, Erickson has used aerial images borrowed from the
military, scientists, and even oil companies, to guide his fieldwork.
What he's discovered about the prehistoric Amazon challenges many
textbook teachings. Before Columbus, he argues, the area was heavily
populated and agriculturally advanced. His work has led to a
surprising supposition: Humans may have engineered nearly every aspect
of the
Amazon landscape.
As an undergraduate, Erickson wasted no time becoming an
archaeologist. He was part of an excavation on the first day of
freshman-year classes and then spent two summers at digs on Lake
Titicaca in South America. The biggest discovery of his young career
came at the end?in the rear-view mirror of a beat-up Volkswagen bus.
The team was departing on a five-hour drive back to "civilization". On
an unpaved, uninhabited stretch of road, cresting over a ridge,
Erickson stole one last glance at the diminishing lakebed. Through the
cracked windows, he couldn't believe what he saw: an unnatural
crosshatch pattern. It covered several square miles, and it seemed to
be human-made.
In this part of the Amazon, farming is difficult. The soil spends half
the year scorched in desert heat and the other half inundated with
rain. For this reason, say scholars, the region is incapable of
sustaining large civilizations. Erickson believes the raised fields he
glimpsed through the back window of his microbus were a solution hit
upon by an ancient people. The system of mounds and canals provided
irrigation in the dry season and drained the soil during floods. Ten
years before, geographer William Denevan had written about the fields,
but by the 1970s, when Erickson was there, no archaeologist had
studied them. No one knew the age of the structures, who built them,
or if they even worked.
By the time Erickson earned a Ph.D., he was itching to return. But as
he hiked the dirt roads in search of the earthen structures he'd
glimpsed before, the ancient fields seemed to have disappeared. From
that point on, he says, "I vowed never to set foot on the landscape
without having studied aerial photographs first." Now he rents a
$300-an- hour Cessna, and a team of three students helps him
photograph the sites from every angle.
With aerial images, Erickson rediscovered the missing raised fields,
and he immediately began analyzing them. Subsequent digs proved that
the mounded fields date back to about 100 B.C. and may have been
cultivated until A.D. 1100. The dimensions of the rectangular plots
were astounding: Each row rose three feet high, measured up to 30 feet
wide, and stretched 1,300 feet long. Between the rows were canals,
also 30 feet wide and three feet deep.
As much as he learned about the fields, he kept coming back to one
nagging question: Were they productive? To answer this, he tried a
little "experimental archaeology", recreating ancient tools and
methods in order to better understand how the raised fields worked.
With help from colleagues and local farmers, he built a field from
scratch and worked it year-round. "We found that productivity was
three to four times traditional practices like slash-and-burn," he
reports. The more time Erickson spent in South America, the more he
kept running into, and collaborating with, a group of sympathetic
researchers, including Denevan and anthropologist William Balée.
Together, the three men challenged conventional thinking about the
Amazon. To begin with, they dismissed "the pristine myth" that the
Americas before Columbus were an untouched Eden. Denevan countered
that, in fact, much of the Amazon is anthropogenic, human made, and
the sheer number of engineered earthworks and their size, he
concluded, would have required a massive workforce.
Looking at an aerial photo of the Baures region of Bolivia, Erickson's
index finger dances between dark polka dots covering bare earth.
These, he notes, are forest islands and mounds that can rise 60 feet
above the savanna. Causeways radiate from them like spokes on a wheel.
Erickson and Balée have shown that the mounds were once settlements,
housing between 500 and 1,000 inhabitants. Beneath the canopies of the
island forests, the two men discovered pottery, bones, and orchards of
fruit trees. The dozens of raised causeways, however, still leave
Erickson scratching his head. Most are straight as a ruler, stretching
from mound to mound. "It looks like everyone in the society had their
own road and used it once!"
For all the evidence that Erickson and his colleagues have offered,
there is still resistance to the idea of a once populous Amazon.
Old-school anthropol-ogists, like the Smithsonian's Betty Meggers,
hold that the region's aluminum-rich soil couldn't have supported the
agricultural base a large civilization needs to thrive.
Environmentalists push the "pristine myth" and, Erickson fears, often
see his work as "some excuse that we're giving developers to go and
rape the Amazon." Even natural scientists abhor the new
anthropocentric view of the Amazon. "When I give talks at the Field
Museum in Chicago, there is always a bunch of them literally yelling
at me." Meggers went so far as to claim, in the journal Latin American
Antiquity, that "the myth of El Dorado is being revived by
archaeologists."
In an ironic twist, the lost gold of El Dorado may turn out to be that
oft maligned soil. In the 1990s, geologists began examining Amazonian
earth, and though much was inhospitable, large swaths turned out to be
fertile. Called Amazonian Dark Earth, or terra preta by locals, this
near-black soil has amazing properties. Dark Earth retains its
nutrients during tropical rains, while other soil is leeched, and like
potting soil, it is far more productive for growing crops. The trait
that makes it so exceptional, and enigmatic, is its ability to
regenerate. Locals quarry and farm the rich soil, and their supply
always grows back. Dark Earth re-creates itself atop a base layer and
grows, just like a living organism. Scientists are still analyzing the
biology, but Erickson believes the Amazon Indians enriched their earth
with a microorganism, one that resisted depletion and helped
fertilize. If better understood, this process of inoculating poor soil
with a bacterial booster could aid parts of the undeveloped world
starved for agriculture.
Recently, geographers estimated that the creators of this ancient
technology managed to terraform at least 10 percent of Amazonia, an
area the size of France. Along with the raised fields, fish weirs,
causeways, and other anthropogenic features, Dark Earth may in fact be
one of countless footprints left by a lost civilization. Indeed, if
Erickson is right, the Amazon could be humankind's largest engineering
relic.
Copyright ©2004 University of Pennsylvania
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Not for commercial use. Solely to be fairly used for the educational
purposes of research and open discussion. Contents do not necessarily
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