Past Human Impacts in Amazonia
The unexpected discovery of immense geometrically patterned earthworks called «geogphyhs» among the terra firme rainforests of western Amazonia is radically changing our notion of past human societies in this region of the Amazon.
Over 300 of these spectacular geometric earthworks have been found across eastern Acre state, Brazil. Prior to the onset of large-scale deforestation in the 1980s, Acre state was completely blanketed by terra firme humid rainforest, assumed by most tropical ecologists to be pristine or virgin.
Only after large-scale deforestation, did these previously hidden earthworks become visible. These earthworks comprise circles, squares, and other geometric shapes, between 90 and 300 m diameter. Most occur on inter-fluvial uplands atop a 150 – 200 m plateau.
Their purpose, and scale of environmental impact associated with their construction, is still debated. Funded by National Geographic Society and in collaboration with archaeologist Denise Schaan we have started a project to investigate what was the past impact of the «Geoglyph Builders» on this region of Amazonia and what is the modern legacy of their ancient land use. To tackle these questions we are using a multi-proxy approach, combining analyses of pollen, phytoliths, stable carbon isotopes, and charcoal, from radiocarbon-dated soil profiles and lake sediments from eastern Acre, which will be able to capture the rise and fall of the «Geoglyph-Building» culture.
Some important publications and web-sites
Mayle, F. and J. Iriarte. in press. Integrated palaeoecology and archaeology – A powerful approach for understanding pre-Columbian Amazonia. Journal of Archaeological Science. [Abstract]
Ranzi, A., Feres, R. and Brown, F. 2007. Internet Software Programs Aid in Search for Amazonian Geoglyphs.American Geophysical Union – EOS (88)21:226- 229. [Open access]
Schaan, D., M. Pärssinen, A. Ranzi and J. Piccoli. 2007. Geoglifos da Amazônia ocidental: Evidência de complexidade social entre povos da terra firme. Revista de Arqueologia SAB 20:67-82. [Open access]
Pärssinen, M., D. Schaan and A. Ranzi. 2009. Pre-Columbian geometric earthworks in the upper Purus: a complex society in Western Amazonia. Antiquity 83:1084-1095. [Abstract]
Schaan, D. P. 2012. Sacred Geographies of Ancient Amazonia: Historical Ecology of Social Complexity. New Frontiers in Historical Ecology 3. Left Coast Press, Walnut Creek.
Schaan, D., M. Pärssinen, S. Saunaluoma, A. Ranzi, M. Bueno and A. Barbosa. 2012. New radiometric dates for precolumbian (2000?700 bp) earthworks in western Amazonia, Brazil. Journal of field archaeology 37:132-142. [Abstract]
Ancient Earthmovers of the Amazon [Science]
Dr. Denise Pahl Schaan, Programa de Pós-Graduação em Antropologia, Universidade Federal do Pará, Brazil.
Dr. Francis Mayle, Institute of Geosciences, University of Edinburgh.
Dr. Alceu Ranzi, Laboratorio de Pesquisas Paleontologicas, Universidade Federal do Acre.