Ancient Amazonian Earthwork Roads: Unveiling Ceremonial, Livelihood, and Networking Significances

Abstract By using satellite images, this study confirms 350 km of ancient roads, comprising 634 wide and 321 narrow roads, in southwestern Amazonia’s earthwork-rich landscape. The roads were straight, mostly under 500 m long, but with some extending several kilometers. They occurred most prevalently in areas of dense earthwork. Nested earthworks were more road-rich than simple ones, and roads were more common in structures with quadrilateral rather than roundish shapes. Geoglyphs typically featured wide ceremonial roads with start widths ranging from 15 to 40 m, sometimes wider, and gradual narrowing toward their distal ends. Mound settlements had narrow, short roads pointing in various directions, which may have been for everyday travel. They also presented narrow but long roads leading to distant destinations, occasionally spanning many earthworks. When the endpoint was observable, 39.7% of roads led to a riverine environment indicating access, 10.6% connected to other earthworks reflecting integration, and 49.7% faded into currently open terrain. Many roads starting from geoglyphs aligned with the cardinal directions suggesting a possible awareness of astronomical alignments in the construction of the ditched ceremonial enclosures. This study confirms that ancient roads provide key insights into past civilizations and are essential to the region’s archaeological heritage.