Planar deformation features in quartz from the Xuanhan crater in China. Microscopic features in silicate mineral grains... very narrow planes of glassy material arranged in parallel sets. These have distinct orientations with respect to the grain’s crystal structure. And here’s why this matters: PDFs are only produced by extreme shock compression on the scale of meteor impacts. They are not found in volcanic environments. This is the smoking gun. The definitive evidence that separates cosmic cat