Ancient Impacts that Allegedly Ravaged Earth Conveniently "Without Leaving Craters" [Updated]

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According to a popular science article by Fernandez (2025), scientists are uncovering "signs that Earth has been hit by powerful cosmic blasts that leave little trace on the surface yet unleash extraordinary heat and pressure. New analyses from ocean floors, ancient settlements, and modern historical events reveal a pattern of explosive airbursts that may have shaped past climates and civilizations". She writes that "touchdown airbursts", are a form of cosmic impact that leave little surface effect and although they can be destructive may occur more often than the crater-producing events and as such are still not fully understood. It seems that this article is largely based on an interview with UC Santa Barbara Earth Science Emeritus Professor James Kennett and is based on four cases he was involved with. These highlight evidence for multiple airbursts from different periods in Earth’s past, in which an incoming object such as a comet detonates above the surface and releases intense heat and shockwaves. Researchers have documented findings about such events from locations ranging from the deep North Atlantic to the remains of an ancient desert community. Their work points to materials that form only under extreme conditions, such as rare comet-derived elements, molten glass, and spherules produced by high-temperature melting of Earth materials, and shocked quartz that contains distinctive fracture patterns.

The first was discussed in a study in the journal PLOS One. The multi-author article describes the claimed discovery of impact proxies in ocean sediments linked to the Younger Dryas Impact Hypothesis in several deep-sea cores taken from Baffin Bay, just west of Greenland.

“Baffin Bay is very significant because it’s the first time we’ve found evidence for the Younger Dryas cosmic impact event in the marine record,” Kennett said. The Younger Dryas hypothesis proposes that a fragmented comet exploded above Earth approximately 12,800 years ago. This event is thought to have triggered an abrupt cooling period known as the Younger Dryas, contributed to the disappearance of many large animals, and influenced major shifts in human cultures and populations. Because the comet broke apart, multiple explosions likely caused widespread fires that left behind a “black mat” layer rich in carbon.

The second case she mentions concerns a shallow seasonal lake near Perkins in southeast Louisiana. This comet theorists claim

"could be the first known [...] crater formed during the YDB. Reporting in the ScienceOpen journal Airbursts and Cratering Impacts, the research team followed up on a speculation first made in 1938 by the property owner that the seasonal lake could be an impact crater based on its shape and a “crater-like rim raised about 1 meter above the surrounding terrain.” It wasn’t until 2006 that the sediments in and around the shallow depression began to be examined for impact proxies; from then until 2024, the team also examined sediment from several lake cores, finding spherules, meltglass and shocked quartz, which they determined by radiocarbon dating to support the Younger Dryas impact event. Nevertheless, the researchers said that “further research would be beneficial for testing the hypothesis that the lake/depression resulted from a cosmic impact.”

The evidence from the Tunguska event was also examined in a paper in Airbursts and Cratering Impacts, this was an airburst that occurred over Siberia in 1908is the only recorded historical touchdown event, with documented eyewitness reports of a fireball in the sky, and photographs of flattened trees.

However, for all the studies of the fallen trees and the soils at the impact site, there had up until now been little effort in search of cosmic impact proxies. This study is the first comprehensive evidence of airburst/impact proxies at Tunguska. The researchers’ analysis of Tunguska revealed shocked quartz grains with the telltale planar deformations and fractures, some filled with meltglass. In addition, they found impact-produced spherules and melted metal and carbon. The high energies related to this impact may also have produced small ground depressions, now existing as swamps and lakes.

More controversially the text mentions the attempts to revisit the evidence from Tall el-Hammam in the southern Jordan Valley, the site of a major Middle Bronze Age city in the Levant that is thought by some comet enthusiasts to have experienced a cosmic airburst event about 3,600 years ago.

"In addition to previous reporting of the usual suspects of spherules, carbon, meltglass, and rare minerals, the researchers have described shocked quartz with a variety of fracture patterns similar to those in Tunguska sediments, including the classical parallel cracks, but also web-like, curved, and sub-planar fissures, indicative of a range of high pressures and directionality resulting from the blast."

Fernandez concludes that taken together, these papers point to the idea that cosmic impacts, and in particular touchdown airbursts, may occur more often than previously thought. And quotes Prof. Kennet: “They’re far more common, but also possess much more destructive potential than the more localized, classic crater-forming asteroidal impacts [...] The destruction from touchdown events can be much more widespread. And yet they haven’t been very well studied, so these should be of interest to humanity.”

[Update]

The Tall-el-Hamman article was retracted by the publisher 24 April 2025 BEFORE Fernandez was writing - she does not mention it Retraction Note: A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea.

The Baffin Bay article was retracted by the publisher on February 11, 2026 Retraction: A 12,800-year-old layer with cometary dust, microspherules, and platinum anomaly recorded in multiple cores from Baffin Bay.

References:

Sonia Fernandez 2025, 'Scientists Uncover New Evidence of Ancient Airbursts That Ravaged Earth Without Leaving Craters' SciTechDaily December 2, 2025.

Ted E. Bunch, Malcolm A. LeCompte, A. Victor Adedeji, James H. Wittke, T. David Burleigh, Robert E. Hermes, Charles Mooney, Dale Batchelor, Wendy S. Wolbach, Joel Kathan, Gunther Kletetschka, Mark C. L. Patterson, Edward C. Swindel, Timothy Witwer, George A. Howard, Siddhartha Mitra, Christopher R. Moore, Kurt Langworthy, James P. Kennett, Allen West & Phillip J. Silvia 2021, 'A Tunguska sized airburst destroyed Tall el-Hammam a Middle Bronze Age city in the Jordan Valley near the Dead Sea' Nature Scientific Reports volume 11, Article number: 18632 (2021)

 Christopher R. Moore, Vladimir A. Tselmovich, Malcolm A. LeCompte, Allen West, Stephen J. Culver, David J. Mallinson, Mohammed Baalousha, James P. Kennett, William M. Napier, Michael Bizimis, Victor Adedeji, Seth R. Sutton, Gunther Kletetschka, Kurt A. Langworthy, Jesus P. Perez, Timothy Witwer, Marc D. Young, Mahbub Alam, Jordan Jeffreys, Richard C. Greenwood and James A. Malley 2025, “A 12,800-year-old layer with cometary dust, microspherules, and platinum anomaly recorded in multiple cores from Baffin Bay” PLoS One. 2025;20(8):e0328347. pmid:40768403   DOI: 10.1371/journal.pone.0328347

Gunther Kletetschka, Marian Takac, Lucie Smrcinova, Radana Kavkova, Dallas Abbott, Malcolm A. LeCompte, Christopher R. Moore, James P. Kennett, Victor Adedeji, Timothy Witwer, Kurt Langworthy, Joshua J. Razink, Valerie Brogden, Brian van Devener, Jesus Paulo Perez, Randy Polson, Teresa M. Eaton, Matthew J. Valente, David B. Lanning Jr., Yoav Rapoport, Argyro Reyes, Ravi Holladay, Michelle Madrigal, Aleksei Kiselev and Allen West  2025, “New Evidence of High-Temperature, High-Pressure Processes at the Site of the 1908 Tunguska Event: Implications for Impact and Airburst Phenomena”  Airbursts and Cratering Impacts. DOI: 10.14293/ACI.2025.0001

Robert Fitzenreiter, Kord Ernstson, Gunther Kletetschka, Malcolm A. LeCompte, Christopher R. Moore, James P. Kennett, Michael Bizimis, Florian Hofmann, Marian Takac, A. Victor Adedeji, Timothy Witwer, Julie E. Chouinard, Jesus Paulo Perez, Marc D. Young, Teresa M. Eaton, Matthew J. Valente, David B. Lanning Jr., Yoav Rapoport, Kailey Ellison, Argyro Reyes, Ravi Holladay, Michelle Madrigal, Julian Albanil, Charlie Sanchez and Allen West, 2025, “Evidence of a 12,800-year-old Shallow Airburst Depression in Louisiana with Large Deposits of Shocked Quartz and Melted Materials” by Airbursts and Cratering Impacts DOI: 10.14293/ACI.2025.0004