The breakup in space of a comet or asteroid prior to impact could produce a surface or oceanic impact by the largest object, and hundreds of smaller fragments could create air-bursts affecting an entire hemisphere (Bunch et al. 2012). Approximately 90% of all ejecta from the main impact would fall within five crater radii, although fine material is expected to be random distributed over a much larger area. Although the type of impact vehicle is still uncertain, the present theory (Napier 2010) is that a fragmented comet produced multiple impacts or airbursts over at least 10% of Earth, releasing an estimated 10 × 10 6 tonnes of Fe spherules (Wittke et al.2013)

Weathering Rinds as Mirror Images of Palaeosols: Examples from the Western Alps with correlation to Antarct… by George Howard

mark boslough Sandia Labs William C. Mahaney Younger Dryas Impact