Pre-Columbian Ring Ditches along the Yacuma and Rapulo Rivers, Beni, Bolivia: A Preliminary Review.

Pre-Columbian farmers built a variety of earthworks in the Llanos de Mojos, part of the Bolivian Amazon. Raised fields, canals, causeways, and mounds of various types in this region date to ca. 800 B.C-AD. 1600. In central Mojos, archaeological work was carried out along the Yacuma, a large west-bank tributary of the Mamoré River. Four ring ditches and two areas of associated raised agricultural fields were mapped. The Global Positioning System was used to document earthworks under the forest canopy which were analyzed within a Geographic Information System. Ceramic evidence is also included. The ring ditches in this study expand the known range of such earthworks in Mojos by 200 km. This revised distribution of ring ditches changes interpretations of the long-term history of Arawak speakers in Mojos and throughout Amazonia. While earthworks in Mojos clearly represent systems of intensive agriculture, they cannot be associated only with Arawak speakers or with Arawak languages. [ABSTRACT FROM AUTHOR]