The Younger Dryas Impact Hypothesis (YDIH) proposes that a cometary or meteoric body exploded over the North American area sometime around 12,900-years-ago.
Proponents of this theory suggest that the event triggered the Younger Dryas (YD) cooling period at the end of the Last Glacial Period, leading to the extinction of Pleistocene megafauna and the decline of the Clovis archaeological culture.
One of the obvious arguments against the YDIH is the apparent lack of craters from the time of the impact. However, according to a new study published in the Science Open Journal - “As of now, we don't have a crater or craters,” said Christopher Moore, an archaeologist at the University of South Carolina and an author of the study.
Computer simulations have shown that a comet could explode before reaching the ground, creating a shock wave capable of widespread impacts without leaving a distinct crater in the planet's geology.
According to Moore, minerals and artefacts found in the soil strata from the YD period are “proxies” of a comet strike—findings that are not direct evidence, but which do tell a story.
This is supported by ice cores from Greenland, in which the study has found elevated levels of combustion aerosols that indicate a massive prehistoric fire occurred at the start of the YD.
Supporting Moore’s argument are traces of platinum in sites across Syria and South Carolina, a rare metal but abundant in comets, and microscopic balls of iron called “microspherules” at various locations across the globe, suggesting some ancient event transported melted iron on a global scale.
A more recent discovery involves “shock-fractured quartz” found in South Carolina, Maryland and New Jersey. The minerals have microscopic cracks where quartz morphed into melted silica through a significant impact event.
Excavations of the YD period layer at all three locations have revealed significantly higher quantities of shock-fractured quartz, platinum, and microspherules, compared to soil strata from earlier and later periods.
According to the study: “This was the first time that shock-fractured quartz has been found at the YD depth at multiple sites. But it’s also one of the first studies to look for shock-fractured quartz, so additional samples may surface in more widespread studies.”
Moore's findings suggest that a comet struck the earth, scattered minerals far and wide, and caused a massive fire that could have consumed the plants eaten by giant mammals, while the smoke resulting from the fire could have triggered a period of global cooling, namely, the YD.
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Sources : University of South Carolina | Christopher R. Moore, Malcolm A. LeCompte and James P. Kennett et al. Platinum, shock-fractured quartz, microspherules, and meltglass widely distributed in Eastern USA at the Younger Dryas onset (12.8 ka). Airbursts and Cratering Impacts. 2024. Vol. 2(1). DOI: 10.14293/ACI.2024.0003