This has been a satisfying week for the Younger Dryas Impact Hypothesis.
For years, critics of the hypothesis demanded two things above all else: “show us shocked quartz at the boundary, and show us an impact crater.” Shocked quartz has always been considered the gold standard of impact evidence — a diagnostic proxy from craters and even nuclear test sites. And a crater, of course, is the ultimate calling card of a cosmic impact.
Now we have both.
The Comet Research Group has published a landmark paper in PLOS ONE reporting shocked quartz — with glass-filled fractures — in the Younger Dryas Boundary (YDB) at three classic Clovis sites: Murray Springs (AZ), Blackwater Draw (NM), and Arlington Canyon (CA). These grains don’t just carry lineations; their fractures are filled with melted silica, formed in an instant of catastrophic pressure and heat.
And just months earlier, Robert Fitzenreiter’s Louisiana farm was confirmed as the location of the first Younger Dryas plasma plume crater, a touchdown where a 7,000-degree blast of cosmic plasma scarred the landscape in his own backyard. His family puzzled over that depression for four generations until Robert brought it to the Comet Research Group. Twelve years later, it became peer-reviewed science.
The juxtaposition is striking: the critics demanded shocked quartz and a crater. The Comet Research Group, and citizen scientists like Robert, have delivered both. And yet, we know what comes next. The small circle of specialists who dug their heels in long ago will likely offer no acknowledgment, no curiosity, and certainly no concession. Dead silence is the expectation. Once a position is staked in academia, retreat is rare — even when the very proxies you demanded appear in the exact layer and setting predicted.
Put these discoveries together and the picture sharpens: direct scars in the ground and diagnostic shock in the minerals, both tied to the ~12,800-year catastrophe that coincided with the loss of megafauna, the collapse of Clovis, and the dawn of agriculture.
Here’s my recent conversation with Robert Fitzenreiter, a citizen-scientist hero:
https://youtu.be/wr_cwFwS0RE?si=8gHgq9KtZIj_FIeB
And stay tuned — the Tusk is planning to visit Robert in late October to film an interview and a tour of the site itself.
Highlights from the new PLOS ONE paper
- Shocked quartz with glass-filled fractures occurs in situ at the YDB in three iconic Clovis sites.
- TEM/SEM/EBSD confirm these are genuine shock features, not tectonic artifacts.
- Hydrocode modeling of a ~100-meter comet fragment’s touch-down airburst reproduces the necessary pressures and heat.
- Updated IntCal20 calibrations place all three sites tightly within 12,875–12,775 cal BP.
- The grains occur alongside other YDB markers: microspherules, nanodiamonds, meltglass, platinum spikes, soot, and the familiar “black mat.”
Why it matters
- Shocked quartz and an impact crater — the two central demands of critics — are now on the table.
- The paper demonstrates how catastrophic low-altitude airbursts can shock quartz without leaving a giant Chicxulub-style crater.
- It directly connects the physics of impact with the cultural and ecological break of ~12.8 ka.
- The Comet Research Group has met the critics’ challenge head-on; whether they respond or stay silent will speak volumes.
Links
- Research article (open access): Kennett et al. 2025, Shocked quartz at the Younger Dryas onset (12.8 ka)… — PLOS ONE
- UCSB/Phys.org release: Evidence of cosmic impact discovered at classic Clovis archaeological sites