ABSTRACT
In the 1970s, the military government launched a series of projects promoting the colonization of Amazonia to integrate the region with the national economy. In Acre, deforestation uncovered enormous ring ditches that for many centuries had been concealed by luxurious tropical vegetation. It was a trip to Peru that inspired Ranzi to call the earthworks in Acre geoglyphs. The ditched enclosures known in Brazil as geoglyphs are found in the interfluves of the Acre, Iquiri, and Abun Rivers, on the edges of plateaus. The first two rivers are the Purus River, whereas the Abun River, which forms part of the border between Bolivia and Brazil, is a tributary of the Madeira River. The Cerritos of coastal Uruguay and Brazil are an interesting. They appeared as early as 4,000 years bp, and were the product of hunter-fisher-gather populations who may have been marking their economic territories.
