The stripping away of forests in Africa’s Democratic Republic of Congo has uncovered a 36-46 kilometer wide circular phenomenon thought to be a giant impact crater. Scientists say the feature might be one of the largest such structures discovered in the last decade. The ring shape is clearly visible in satellite images by TerraMetrics Inc, reproduced on the BBC. “Only about terrestrial 25 impact craters are of comparable size or larger, according to the web-based Earth Impact Database. Giovanni Monegato, from the University of Padova, said the feature was revealed only after trees were cleared from the area over the last decade.
The Unia River flows around the ring structure, underlining its round shape. The central part of the Wembo-Nyama feature is irregular and about 550m in elevation. This is about 50-60m higher than the depression where the river flows. Although this might sound counter-intuitive, experts say that impact craters can sometimes lift up dense rocks. The surrounding rocks may subsequently erode, leaving a dome. The putative crater lacks a well-defined outer ridge, though the University of Padova team says this could be explained by deep weathering and erosion in the tropical climate.”