Geography of ancient geometric earthworks and their builders in southwestern Amazonia
: Kalliola, Risto; Pärssinen, Martti; Ranzi, Alceu; Seppä, Iiro; Barbosa, Antonia Damasceno
Publisher: INST NACIONAL PESQUISAS AMAZONIA
: MANAUS
: 2024
: Acta Amazonica
: ACTA AMAZONICA
: ACTA AMAZON
: e54hu22351
: 54
: 4
: 21
: 0044-5967
: 1809-4392
DOI: https://doi.org/10.1590/1809-4392202203511
: https://doi.org/10.1590/1809-4392202203511
: https://research.utu.fi/converis/portal/detail/Publication/458940065
Geometric earthworks are evidence of ancient human activity in western Brazilian Amazonia. We used a review of existing and new data to map earthworks across 27,569 km2 of deforested areas in southwestern Amazonia using satellite imagery. We developed a conceptual basis for the classification of earthworks based on their structural characteristics using fuzzy sets. We recorded 1,279 structures with a distinctive core density zone. Most of the structures displayed geometric shapes, but they varied in construction accuracy. Geoglyphs accounted for 80% of all objects, with geographically variable shapes and enclosure areas. Other earthwork types included associated embankments, solitary embankments and mound sites. The abundance of earthworks provided evidence of strong pre-European human influence on the study area. A 10-km buffer around each earthwork included 75% of recent deforestation areas and 25.7% of standing forest, suggesting a significant potential for the presence of further earthworks in this ancient anthropogenic landscape and its possible far-reaching ecological legacy. The available radiocarbon data confirm a long-term anthropogenic impact in the study area, with ceremonial geoglyphs indicating activities over a thousand years old and other structures revealing more recent cultural transformations.
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We extend our gratitude to our collaborators at our home institutions, James Q. Jacobs, Francisco R Nakahara, and the other discoverers of ancient earthwork sites. We also acknowledge the Academy of Finland for funding research projects 296406 (RK) and 297161 (MP) . In Brazil, the research was authorized by the Instituto do Patrimpnio Historico e Artistico Nacional (IPHAN license #01423000336/2017-11) . Our heartfelt thanks go to our long-term close collaborators Denise Schaan and Heli Paerssinen, and we dedicate this research to their memory.
