Araona Crater (Iturralde Structure) With Labels

The Araona Crater (also known as the Iturralde Structure) is a suspected crater from an impactor which struck northern Bolivia approximately 20,000 years ago. The feature is believed to have been caused by a short period comet striking at 70 kilometers per second and splattering into the muddy alluvial flood plain in the Lower Amazon jungle. The impact created a circular depression which is now roughly 8 kilometers across and 3 meters deep. The structure was discovered in 1988 Landsat data, but was not visited successfully until 1998 because the region is inaccessible. Future expeditions hope to finally settle if the feature truly is the impact crater it appears to be, and if so, determine the nature of the impactor. The full Landsat scene of Northern Bolivia includes the Rio Bene running northward through the image (North is up), with the Rio Madidi running across the image from southwest towards the northeast before joining the Rio Bene. The image was constructed from Landsat Thematic Mapper bands 7, 5, and 3 displayed as red, green, and blue respectively. The green tone of the image distinguishes between different types of vegetation with low scrubland in the alluvial flood plain appears as a light green and dense tropical jungle coverage appearing dark green. The close-up of the impact crater uses the same Landsat data, but passed through a sharpening image filter which emphasizes high spatial frequency features and tends to enhance color contrast.

See http://svs.gsfc.nasa.gov/stories/Landsat/index.html