From the Skeptic Encyclopedia of Pseudoscience - excerpt from an article by Allan Harris

"A more recent summary of the current status of Tunguska research is published by Valilyev (1998, and web site). This article is the introductory article to an entire proceeding of a scientific meeting devoted to the study of the Tunguska event, held in Bologna, Italy in 1996. These references provide a thorough description of the physical evidence surrounding the Tunguska event, including the estimates of the path of the incoming body, the visual and sonic phenomena, tree fall and burn patterns, and the results of careful examination and sample collecting from the sites.
A few additional facts have emerged from recent expeditions, perhaps most significantly the identification of traces of meteoritic material, including small dust grains embedded in tree sap dating from the time of the event and anomalous concentrations of the element iridium in the peat bog that lies directly under the explosion site, in a layer corresponding to the time of the event. Excess iridium is associated with cosmic impacts, most notably the one 65 million years ago that led to the extinction of the dinosaurs. This evidence quite conclusively argues that Tunguska was not an alien spaceship crash or impact of a black hole or antimatter, but was instead a more ordinary arrival of a small asteroid or comet. Unfortunately, a comet, although containing some icy material, would also have plenty of cosmic dust so the distinction between comet or asteroid is not resolved by this discovery."

Doug Weller

Director The Hall of Ma'at
Doug's Skeptical Archaeology site::
[www.ramtops.co.uk]