Lidar Survey Maps Thousands of Ancient Earthen Platforms and Mounds in Ecuador's Upano Valley

Analyses of 2015 Lidar data have identified nearly 7,500 man-made structures across a 600-square-kilometre area of Ecuador's Upano Valley, including more than 5,000 earthen platforms, about 1,500 hills and hundreds of rounded mounds, plazas, terraces, paths, roads, ditches and drainages.

The platforms are mostly rectangular, 2-3 metres tall and roughly 10 by 20 metres at the base, though some reach 8 metres in height and 40 by 140 metres. Archaeologists say the smaller mounds supported daily activities while larger ones likely served ceremonial purposes.

Local researchers had known of some formations for 50 years. Jesuit priest Pedro Porras began systematic study in 1978 after a tip from a friend and spent more than 200 days excavating 15 areas. In the 1990s, additional small excavations and preliminary mapping followed.

In July 2015 the Ecuadorian National Institute for Cultural Heritage commissioned an airborne Lidar survey. Detailed examination of the resulting data began around 2023. One 2023 study commissioned by the institute catalogued the structures; a 2024 French analysis examined the same scans; and Alden Yépez's team at Pontificia Universidad Católica de Ecuador produced a publicly available 3D map.

Rita Litben, an independent researcher in Guayaquil, and Alejandra Sánchez Polo of the Universidad de Valladolid co-authored the institute-commissioned analysis. Stéphen Rostain, director of investigation at the French National Centre for Scientific Research, led the 2024 study.

Rostain's earlier work documented straight, 2-15-metre-wide trenches up to 5 metres deep that extend as far as 25 kilometres.

Starch grains recovered from ancient pottery indicate cultivation of maize, beans, manioc and sweet potato. " Rostain calls the water-management theory "ridiculous" and unfounded. All three research groups date the main construction period to roughly 3,000-2,500 years ago.

Rostain argues the original Upano inhabitants abandoned the sites briskly around AD 600 because of the Medieval Climate Anomaly and were succeeded by the Huapula people, who remained until at least the 13th century. Yépez's team cites sediment and pottery evidence for a slower, more gradual transition.

Florencio Delgado, professor of anthropology at Universidad San Francisco de Quito, notes that questions remain about social organisation and population size.

As many as 90 percent of Lidar data points are still unclassified, and only half the scanned area has been studied. The institute has released the remaining data to Rostain. Local group Guardians of Patrimonies reports mound destruction to authorities and educates landowners.

Pottery from the Huapula site is held at Museo Gonsha. Mark Bush, a palaeoecologist at the Florida Institute of Technology, states that the vegetation visible today results from changes in the past 200-300 years. Michael Heckenberger of the University of Florida describes the settlements as a multicentric, low-density form of Amazonian urbanism distinct from European city models.

In 2024 Rostain's paper drew media attention and some criticism for possible inaccuracies and inadequate crediting of prior work. A 2025 paper by Kathryn Reese-Taylor of the University of Calgary examined media descriptions of the findings.