No. 104: Mar-Apr 1996
Microscopic examination and microprobe analysis led to the following conclusions:
"Although direct evidence of an extraterrestrial origin for this debris layer (such as the presence of cosmogenic 10 Be and 26Al) has not yet been obtained, the available data strongly suggest that this sediment originated as meteoritic spallation debris. This debris is distinct from other Antarctic 'cosmic dust' collections by virtue of its uniform, recognizable, ordinary chondrite composition and the consistent relation shown between grain size and texture. The BIT-58 layer probably originated from a single transient event, the passage and/or impact of a single large meteorite over the East Antarctic icesheet."
(Harvey, R.P. et al; "A Meteoritic Event Layer in Antarctic Ice," Meteoritics, 30:517, 1995)
Comment. The Petrozavodsk Phenomenon under ASTRONOMY might well have left a layer like this. The 1908 Tunguska Event (Siberian Meteor) undoubtedly did. (SF#102)