Rosa Rubicondior: Refuting Creationism - Fine Tuned For Catastrophe

Researchers find evidence of cosmic impact at classic Clovis archaeological sites | The Current

A new paper in PLOS One presents compelling evidence that a comet exploding in Earth’s atmosphere around 13,000 years ago played a major role in the extinction of megafauna such as mammoths and mastodons across Eurasia and North America, and in extinguishing the Clovis Culture, the archaeological sites of which provided the evidence for the impact. The study was led by James Kennett, Professor at University of California, Santa Barbara, working with an international team of collaborators.

The findings cut directly across a familiar creationist trope: the claim that Earth is “finely tuned” to be a benign and stable haven, perfectly suited for human life. This notion, often promoted by parochial American creationists, quietly assumes that the wider world is a trivial backdrop where nothing of consequence ever happens. It ignores the obvious realities of earthquakes, floods, famines, volcanic eruptions and climate shocks—realities that dominate both human history and the deep geological record.

That record tells a very different story. Earth’s past is marked by repeated catastrophes, ranging from abrupt climate shifts to mass extinctions, many triggered by astronomical or geological events. Impacts from space, massive volcanism, plate tectonics and cascading ecosystem failures have repeatedly reshaped life on this planet. Far from being a delicately balanced paradise, Earth is a dynamic and often hostile environment in which survival has always depended on adaptation—and, frequently, sheer luck.

Background^ Earth’s Repeated Mass Extinctions.

Mass Extinctions
National Geographic

Timing
Over the past ~540 million years, Earth has experienced at least five major mass extinctions, each eliminating a substantial fraction of global biodiversity in geologically short intervals (thousands to hundreds of thousands of years). These events punctuate the fossil record and separate major evolutionary eras.

Causes
No single mechanism explains all mass extinctions. Instead, different events were driven by different—sometimes overlapping—triggers:

Astronomical impacts (e.g. large asteroids or comets), injecting dust and aerosols that blocked sunlight and disrupted climate and food webs (as with the end-Cretaceous event linked to the **Chicxulub Crater**).
Large-scale volcanism, releasing vast quantities of CO₂, sulphur gases and toxic metals, causing rapid warming, acid rain and ocean acidification (notably at the end-Permian).
Abrupt climate change, including rapid warming or cooling, often amplified by feedbacks in oceans and ice sheets.
Ocean anoxia, where warming and nutrient disruption lead to oxygen-starved seas, collapsing marine ecosystems.

Consequences

Severe biodiversity loss, often exceeding 70–90% of species globally.
Ecosystem collapse, with food webs simplified or wiped out entirely.
Evolutionary bottlenecks, followed by long recovery periods during which surviving lineages diversify to fill vacant ecological niches.
Biological turnover, reshaping life on Earth—many dominant groups disappear, while previously minor ones rise to prominence.

Taken together, mass extinctions show that Earth’s history is not one of steady, benign stability, but of repeated disruption and renewal. Life persists not because the planet is finely tuned to avoid catastrophe, but because evolution is resilient in the aftermath of it.

The new research, and its wider implications, are clearly explained in a UC Santa Barbara news feature by Sonia Fernandez, which sets the study in the broader context of Earth’s long history of environmental upheaval and biological turnover.

Researchers find evidence of cosmic impact at classic Clovis archaeological sites
Researchers continue to build on a body of evidence for a fragmented comet that is thought to have exploded over the Earth almost 13,000 years ago, which may have had a role in the disappearance of mammoths, mastodons and most of other megafauna at that time, and in the vanishing of the Clovis culture from the archaeological record in North America.
Reporting in PLOS One, UC Santa Barbara Emeritus Professor of Earth Science James Kennett and collaborators present their findings of shocked quartz — grains of sand deformed by extreme pressures and temperatures — at three classic Clovis culture archaeological sites in the United States: Murray Springs in Arizona, Blackwater Draw in New Mexico and Arlington Canyon in California’s Channel Islands.

These three sites were classic sites in the discovery and the documentation of the megafaunal extinctions in North America and the disappearance of the Clovis culture.

Professor James Kennett, first author.
Department of Earth Science and Marine Science Institute
University of California, Santa Barbara
California, USA.

This work made use of the University of Utah USTAR shared facilities supported, in part, by the MRSEC Program of the National Science Foundation.

Evidence for the Younger Dryas Impact hypothesis

The disappearance of the megafauna and the vanishing of the Clovis technocomplex from the archaeological record coincide with the onset of the Younger Dryas cool episode, an anomalous and abrupt return to near ice-age conditions that persisted for about a thousand or so years amid what was generally a warming transition from the Last Glacial Period.

There are several hypotheses for what may have happened to trigger that event; Kennett and team propose a scenario in which a fragmented comet exploded aboveground, sending shockwaves and extreme heat to Earth.

According to the Younger Dryas impact hypothesis, the explosions were responsible for widespread burning and the resulting smoke and soot, in addition to dust that blocked the sun, leading to an “impact winter.” Rapid melting of the ice sheets could have helped to further cool the impact zones. The shock of impact itself, followed by harsh conditions thereafter, may have contributed to the demise of the megafauna in both North and South America and the disappearance of the Clovis culture, according to the hypothesis.

In other words, all hell broke loose.

Professor James Kennett.

For the past couple of decades, Kennett and fellow proponents of this hypothesis have been gathering evidence that increasingly supports it, including a “black mat” layer in the sediment at many sites across North America and Europe — indicative of widespread burning. Additionally, they have uncovered a growing list of impact proxies, which include unusually high concentrations of rare minerals that are common in comets, such as platinum and iridium, and mineral formations indicative of extremely high temperatures and pressures, such as nanodiamonds and metals and minerals that have melted, cooled and hardened again, including metallic spherules and meltglass.

The three classic Clovis archaeological sites in the study.
Photo Credit: Courtesy Image.

Thanks to advances in technology, the team is homing in on another proxy that is considered the crème de la crème of cosmic impact evidence: shocked quartz — grains of sand that exhibit deformations due to extreme heat and temperature. In samples from the three North American archaeological sites — Murray Springs, Blackwater Draw and Arlington Canyon — the researchers identified quartz grains with telltale cracks, some filled with melted silica. They used a variety of techniques, including electron microscopy and cathodoluminescence, to confirm that the quartz grains had been shocked at extremely high temperatures and pressures, far beyond what could have been accomplished by volcanism or ancient human activity.

The presence of shocked quartz is particularly important in the absence of craters — the smoking gun of cosmic impact evidence. Unlike the asteroid that killed off the dinosaurs 65 million years ago and left a crater beneath the Yucatan Peninsula, “touchdown airbursts” — cosmic collisions that occur above the Earth’s surface, such as from this proposed fragmented comet — leave little, if any, evidence on the landscape. Using hydrocode modeling, the team modeled these low-altitude, above-ground explosions and the variety of impacts that could lead to the shock patterns in the quartz grains.

“There are different levels of shocked quartz,” Kennett said. While the accepted evidence for cosmic impact leans heavily on the parallel cracks in quartz found at craters, the variety of directions, pressures and temperatures that emerge around airbursts would lead to variations in the shock patterns in the quartz, he explained. “There are going to be some very highly shocked grains and some that will be low-shocked. That’s what you would expect.”

Added to the other impact proxies found in the same layer of sediment — carbon-rich black mat, nanodiamonds, impact spherules — and found at three key archaeological sites, the discovery of these shocked quartz grains “supports a cosmic impact as a major contributing factor in the megafaunal extinctions and the collapse of the Clovis technocomplex at the Younger Dryas onset,” according to the paper.

Publication:
Kennett JP, LeCompte MA, Moore CR, Kletetschka G, Johnson JR, Wolbach WS, et al. (2025)
Shocked quartz at the Younger Dryas onset (12.8 ka) supports cosmic airbursts/impacts contributing to North American megafaunal extinctions and collapse of the Clovis technocomplex. PLoS One 20(9): e0319840. https://doi.org/10.1371/journal.pone.0319840

Abstract

Shocked quartz grains are an accepted indicator of crater-forming cosmic impact events, which also typically produce amorphous silica along the fractures. Furthermore, previous research has shown that shocked quartz can form when nuclear detonations, asteroids, and comets produce near-surface or “touch-down” airbursts. When cosmic airbursts detonate with enough energy and at sufficiently low altitude, the resultant relatively small, high-velocity fragments may strike Earth’s surface with high enough pressures to generate thermal and mechanical shock that can fracture quartz grains and introduce molten silica into the fractures. Here, we report the discovery of shocked quartz grains in a layer dating to the Younger Dryas (YD) onset (12.8 ka) in three classic archaeological sequences in the Southwestern United States: Murray Springs, Arizona; Blackwater Draw, New Mexico; and Arlington Canyon, California. These sites were foundational in demonstrating that the extinction or observed population bottlenecks of many megafaunal species and the coeval collapse/reorganization of the Clovis technocomplex in North America co-occurred at or near the YD onset. Using a comprehensive suite of 10 analytical techniques, including electron microscopy (TEM, SEM, CL, and EBSD), we have identified grains with glass-filled fractures similar to shocked grains associated with nuclear explosions and 27 accepted impact craters of different ages (e.g., Meteor Crater, 50 ka; Chesapeake Bay, 35 Ma; Chicxulub, 66 Ma; Manicouagan, 214 Ma) and produced in 11 laboratory shock experiments. In addition, we used hydrocode modeling to explore the temperatures, pressures, and shockwave velocities associated with the airburst of a 100-m fragment of a comet and conclude that they are sufficient to produce shocked quartz. These shocked grains co-occur with previously reported peak concentrations in platinum, meltglass, soot, and nanodiamonds, along with microspherules, similar to those found in ~28 microspherule layers that are accepted as evidence for cosmic impact events, even in the absence of a known crater. The discovery of apparently thermally-altered shocked quartz grains at these three key archaeological sites supports a cosmic impact as a major contributing factor in the megafaunal extinctions and the collapse of the Clovis technocomplex at the YD onset.

Fig 3. YDB proxies for Arlington Canyon, Santa Rosa Island (A, B), California, USA.
This figure summarizes the stratigraphic context and proxy evidence for a potential Younger Dryas impact event near Arlington Canyon, a well-dated coastal site on Santa Rosa Island. (A) Location in Southwestern USA (lat/long: 33.990333°N, 120.1580555°W). (B) Aerial view of the site. (C) This profile is exposed on a 5-m-high cliff of a low terrace cut by a stream ~2 km inland from the NW coast of Santa Rosa Island. Detailed stratigraphy and chronology are in Kennett et al. [63]. The 44-cm-thick YDB layer at the cliff base contains proxy abundance peaks in a black silty mud layer. (D) All proxy abundance peaks are significantly higher than background concentrations. The darker blue horizontal bar represents the YDB layer with a Bayesian-modeled radiocarbon age of 12.8 ka (revised range: 12,875−12,775 cal BP) [48]; the lighter blue bar represents the upward distribution of YDB proxies considered to be reworked (SI, Table S5 in S1 File). The graph depicts a new proxy from this study: glass-filled fractured quartz at an abundance of 5 grains in ~8,000 quartz grains on a 27 x 46 mm slide with none above. Other proxies from previous studies: (E) Microspherules from Wittke et al. [44]. (F) Nanodiamonds [49,54,88]. (G) Carbon microspherules from biomass burning [44,63]. (H) Soot/aciniform carbon from biomass burning [12,24,89]. (I) Platinum [45]. Panel A is courtesy of the U.S. Geological Survey, accessed at https://apps.nationalmap.gov/viewer/ on 01/28/2025. Panel B is courtesy of the Library of Congress, Prints and Photographs Division, the Jon B. Lovelace Collection of California Photographs in Carol M Highsmith’s America Project; the photo is in the public domain.

Fig 4. YDB proxies at Blackwater Draw, New Mexico, USA.
This figure presents stratigraphic and geochemical evidence for a potential impact event near Blackwater Draw, the type-site for the Clovis culture and a key location for investigating the YDB layer. (A) Location in Southwestern USA (lat/long: 34.275687°N, 103.326101°W). (B) Aerial view of site, overlaid on a 3D digital elevation model (DEM). This is the initial Clovis artifact discovery site, 18 km SE of Clovis, New Mexico. The sampling location is inside the South Bank Interpretive Center. Haynes [2] reported that the black mat at this site dates to 12,855 ± 80 (13,060−12,735 cal BP) [64,79]. YDB abundance peaks in YDB proxies exceed background concentrations. The blue horizontal bar marks the YDB layer with a Bayesian-modeled radiocarbon age of ~12.8 ka (revised range: 12,875−12,775 cal BP), calculated using probabilistic methods that incorporate stratigraphic constraints and prior information to refine radiocarbon date estimates (SI, Table S6-S7 in S1 File). (C) The YDB layer is a 1-cm-thick dark-gray stratum (arrow) at a ~ 2.5 m depth. Abundance peaks in various proxies occur in the YDB layer. The new proxy reported here is (D) Glass-filled fractured quartz at 7 grains in ~18,000 quartz grains on a 27 x 46 mm slide with none above or below. Other proxies from previous studies: (E) Microspherules [1,44,58]. (F) Nanodiamonds [54]. (G) Carbon microspherules from biomass burning [12,24,44]. (H) Black carbon from biomass burning [12,24,89]; and (I) Platinum [45,58]. A nearby butchered mammoth skeleton, stained black by the 12.8 ka black mat, indicates the animal was killed at or close to the time of the YDB event [1,44]. No in situ Clovis points or mammoth remains have been found above the YDB layer here or at other known sites [1,44]. The figure is from the U.S. Geological Survey, composited from NAIP Plus aerial imagery, 3DEP Elevation multi-directional hillshade data, and 3DEP elevation aspect data, accessed at https://apps.nationalmap.gov/viewer/ on 01/28/2025.

Fig 5. YDB proxies at Murray Springs, Arizona, USA.
This figure illustrates the stratigraphic setting and proxy evidence for a potential Younger Dryas impact event near Murray Springs, a key Clovis archaeological site with well-preserved megafaunal and cultural remains. (A) The location is in the Southwestern USA (lat/long: 31.570912°N, 110.177996°W), 10 km east of Sierra Vista, Arizona. (B) Aerial view of the site, composited with a false-colored map showing the terrain slope. (C) The black mat at ~2.46 m is immediately above the ~ 1 cm-thick YDB layer, which contains abundance peaks in YDB proxies. Haynes [2] reported that the black mat at this site dates to 12,805 ± 45 (12,895−12,735 cal BP), with a Bayesian-modeled radiocarbon age of ~12.8 ka (revised range: 12,875−12,775 cal BP) (SI, Table S8 in S1 File). The new proxy reported here is (D) Glass-filled fractured quartz at 4 grains in ~3,000 quartz grains on a 27 x 46 mm slide with none above or below. YDB abundance peak concentrations are represented by the blue horizontal bar and mark the YDB layer. Other proxies reported from previous studies are (E) Microspherules [44]. Haynes et al. [90] confirmed the peak in microspherules but offered an alternate explanation. (F) Nanodiamonds [54]. (G) Carbon microspherules are produced by biomass burning [12,24,44]. (H) Soot/aciniform carbon (black carbon) from biomass burning [12,24,89]. (I) Platinum [45]. Clovis-age projectile points, tools, and a campsite were found in the proxy-rich YDB layer at the site [2]. A butchered, fully-articulated mammoth skeleton, found in the YDB layer just below the black mat and stained black by contact with it, indicates the animal was killed at or near the time of the YDB event [1,44]. No in situ Clovis points or mammoth remains have been found above the YDB layer at this or any other site [1,44]. Figure is from the U.S. Geological Survey, composited from NAIP Plus aerial imagery, 3DEP Elevation multi-directional hillshade data, and 3DEP elevation aspect data, accessed at https://apps.nationalmap.gov/viewer/ on 01/28/2025

Kennett JP, LeCompte MA, Moore CR, Kletetschka G, Johnson JR, Wolbach WS, et al. (2025)
Shocked quartz at the Younger Dryas onset (12.8 ka) supports cosmic airbursts/impacts contributing to North American megafaunal extinctions and collapse of the Clovis technocomplex. PLoS One 20(9): e0319840. https://doi.org/10.1371/journal.pone.0319840

Copyright: © 2026 The authors.
Published by PLoS. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

This evidence leaves creationist claims about a carefully engineered, human-friendly world in ruins. A planet that periodically wipes out much of its own biosphere through impacts, volcanism and runaway climate change is not “finely tuned” in any meaningful sense. It is dangerous, unstable and frequently lethal to the life it carries. Humanity exists not because Earth was designed with us in mind, but because our lineage happened—by chance—to survive the most recent in a long series of planetary catastrophes.

The extinction of the megafauna at the end of the last Ice Age fits neatly into this broader pattern. It was not a moral fable, a divinely scripted transition, or a gentle handover to human dominance, but a brutal ecological reset triggered by forces entirely indifferent to human hopes or future aspirations. That some species survived while others vanished is exactly what evolutionary theory predicts in the face of sudden environmental shock.

Once again, science reveals a world shaped by contingency, catastrophe and adaptation, not purpose or foresight. The rocks, the fossils and now the geochemical signatures all tell the same story: Earth is not a cradle carefully prepared for humanity, but a restless planet on which survival has always been provisional. Creationism survives only by ignoring this reality—and each new discovery makes that act of wilful blindness harder to sustain.

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