Shocked quartz in U.S. sediments points to possible cosmic airburst at Younger Dryas onset

New geological analyses of sediments from three well-studied North American sites have identified shocked quartz grains dated to the onset of the Younger Dryas, lending support to the hypothesis that an extraterrestrial airburst or impact contributed to abrupt environmental and cultural changes around 12,800 years ago.

Researchers working at Blackwater Draw (New Mexico), Murray Springs (Arizona) and Arlington Canyon on Santa Rosa Island (California) reported finding mineral grains whose crystal lattices bear irreversible deformation consistent with exposure to sudden, extreme pressures. The grains were extracted from sediment layers precisely dated to about 10,800 BC, a time that corresponds to the rapid disappearance of Clovis-style artifacts from the archaeological record and a major pulse of megafaunal extinctions.

The study, published in PLOS ONE, reports that many of the quartz grains show evidence of exposure to temperatures above the melting point of quartz (about 3,123 °F), with some portions remaining amorphous and others having recrystallized. Team members used 10 different laboratory techniques to identify glass-filled fractures in the quartz and ran computer simulations to estimate the pressures and velocities needed to produce the observed microstructures. The shocked quartz from these southwestern U.S. sites was said to resemble samples from recognized impact or airburst occurrences, including nuclear airburst zones and Meteor Crater, as well as previously reported Younger Dryas–age deposits in Syria, the eastern United States, the Netherlands and Venezuela.

Archaeological and paleontological context at the studied sites aligns with a sudden environmental upheaval. Blackwater Draw, a Clovis-type site where the first Clovis artifacts were identified, contains a distinct organic-rich "black mat" layer dated to roughly 12,800 years ago that overlies Clovis horizons. Nearby remains include a Clovis-butchered mammoth. Murray Springs similarly preserves terminal Clovis artifacts and extinct megafauna beneath a black mat that contains evidence interpreted as the rapid burial of hundreds of footprints and a butchered mammoth. Arlington Canyon yielded Clovis-era human remains below a comparable black-mat layer and records the extinction of island pygmy mammoths; investigators report a 600- to 800-year gap before later human reoccupation there.

In their paper, the authors noted that the onset of the Younger Dryas closely coincided with the sudden extinction of more than 70% of North American megafaunal genera — including mammoths, camels, horses and saber-toothed cats — and the abrupt collapse of the Clovis technocomplex. They argue that the presence of airburst- or impact-related materials at these key locations strengthens a temporal and spatial link between a proposed cosmic event and major ecological and cultural changes at the Younger Dryas onset.

The idea that a large comet or comet fragment passed through the atmosphere and triggered widespread fires, climatic disruption and social upheaval has been advanced for decades and invoked by some authors and researchers. Proponents contend such an event could have injected dust and aerosols into the atmosphere, shading sunlight and contributing to rapid Northern Hemisphere cooling. The new mineralogical evidence is presented by its authors as additional data consistent with an airburst or impact scenario, although the paper describes laboratory and modeling steps taken to distinguish shock-related features from other high-temperature or pressure processes.

The Younger Dryas, an abrupt cooling episode that lasted about 1,200 years, has been the subject of extensive study and debate. Multiple hypotheses have been proposed to explain its onset, including changes in ocean circulation, volcanic activity and extraterrestrial encounters. This study adds mineralogical observations to the body of evidence examined by researchers investigating links between a sudden environmental event and synchronous archaeological and paleontological changes across North America.

The authors conclude that shocked, thermally altered quartz grains from well-dated terminal Clovis deposits provide a geologic marker that is temporally and spatially associated with extinction and cultural discontinuity at the Younger Dryas onset. They emphasize that the sites examined are among the best-documented in North America for studying relationships among megafaunal disappearance, cultural collapse and abrupt environmental change.

Further work by other research teams, including additional sampling, independent laboratory replication and broader regional surveys, will be necessary to evaluate how widely such shocked minerals occur at Younger Dryas–age horizons and to refine understanding of the mechanisms and consequences of any extraterrestrial event at that time.