Late Quaternary history of the Gumants catchment, Papua New Guinea

A massive debris avalanche, estimated to be over 15 km³ and occurring around 400 ± 100 thousand years ago (ka), reshaped the Gumants catchment in Papua New Guinea's central highlands. This geological event altered the flow of the Upper Gumants River, which once connected directly to the Wahgi River via the Guga subcatchment—home to Kuk Swamp, a UNESCO World Heritage Site renowned for its 10,000-year history of agriculture. The study reveals that volcanic deposits, including lahars and airfall tephras (last active ~200 ka), dominate the landscape, with swamp sediments in the Kugimi Basin reaching depths of at least 30 meters—beyond radiocarbon dating limits. Contrary to past speculation, evidence confirms the Gumants River has always flowed eastward, likely joined by the Wahgi River, challenging previous assumptions about their drainage history.

Blong, R. (2023). Late Quaternary history of the Gumants catchment, Papua New Guinea. Australian Journal of Earth Sciences, 71(1), 67–99. https://doi.org/10.1080/08120099.2023.2237117