Overview

• A PLOS One paper reports shocked quartz grains at Murray Springs in Arizona, Blackwater Draw in New Mexico, and Arlington Canyon on California’s Santa Rosa Island.
• The grains occur within the carbon-rich black mat layer dated to roughly 12,800 years ago, coincident with the Younger Dryas onset and the disappearance of Clovis artifacts.
• Analyses using electron microscopy, cathodoluminescence, and other techniques identified glass-filled fractures consistent with extreme pressures beyond volcanism or human activity.
• Hydrocode simulations model low-altitude airburst conditions that could produce the observed shock features, addressing the lack of a crater signature.
• The authors argue the findings support a fragmented comet airburst contributing to megafaunal extinctions and Clovis collapse, though researchers note the hypothesis remains contested and calls for wider, independent corroboration persist.