Saturday, July 26, 2014

Earthen Rings Predate Amazon Rainforest


This is of course a complete surprise. Yet it certain that marginal areas of rainforest are hugely vulnerable to human manipulation.   The hydraulic cycle will be tied directly to tree cover and soil disturbance as we see in the Sahel and the Sahara.  Thus with the removal of a huge population base this area became reforested.
Today in North America we are witnessing the rebirth of the Eastern Woodlands for similar reasons.  In the future, all humanity will participate in the work of grooming all available forests and waste lands in order to optimize natural fertility and productivity.

In the meantime a huge new complex society is been uncovered and we will surely be hearing more.


Mysterious Earthen Rings Predate Amazon Rainforest


These human-made structures remain a mystery: They may have been used for defense, drainage, or perhaps ceremonial or religious reasons. But the new research addresses another burning question: whether and how much prehistoric people altered the landscape in the Amazon before the arrival of Europeans. 

"People have been affecting the global climate system through land use for not just the past 200 to 300 years, but for thousands of years," said study author John Francis Carson, a postdoctoral researcher at the University of Reading in the United Kingdom. (See Images of the Ancient Amazonian Earthworks)
For many years, archaeologists thought that the indigenous people who lived in the Amazon before Christopher Columbus arrived in the Americas in 1492 moved across the area while making barely a dent in the landscape. Since the 1980s, however, deforestation has revealed massive earthworks in the form of ditches up to 16 feet (5 meters) deep, and often just as wide.
These discoveries have caused a controversy between those who believe Amazonians were still mostly gentle on the landscape, altering very little of the rainforest, and those who believe these pre-Columbian people conducted major slash-and-burn operations, which were later swallowed by the forest after the European invasion caused the population to collapse.
Carson and his colleagues wanted to explore the question of whether early Amazonians had a major impact on the forest. They focused on the Amazon of northeastern Bolivia, where they had sediment cores from two lakes nearby major earthworks sites. These sediment cores hold ancient pollen grains and charcoal from long-ago fires, and can hint at the climate and ecosystem that existed when the sediment was laid down as far back as 6,000 years ago.


An examination of the two cores — one from the large lake, Laguna Oricore, and one from the smaller lake, Laguna Granja — revealed a surprise: The very oldest sediments didn't come from a rainforest ecosystem at all. In fact, the Bolivian Amazon before about 2,000 to 3,000 years ago looked more like the savannas of Africa than today's jungle environment.
The question had been whether the early Amazon was highly deforested or barely touched, Carson said.
"The surprising thing we found was that it was neither," he told Live Science. "It was this third scenario where, when people first arrived on the landscape, the climate was drier."


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