Published August 10, 2013 at 446 × 384 in Geochemical ‘fingerprints’ leave evidence that megafloods eroded steep gorge This 2005 image shows a concentration of grains of zircon taken from sand deposits, where it occurs with other heavy minerals such as magnetite and ilmenite. Image credit: U.S. Geological Survey (Visited 3 times, 1 visits today)