Shocked Quartz Discovery Supports Younger Dryas Impact Hypothesis

New research published in PLOS One presents evidence of shocked quartz at several archaeological sites, providing further data relevant to the debate on the Younger Dryas impact hypothesis.

The study identified shocked quartz grains at Murray Springs in Arizona, Blackwater Draw in New Mexico, and Arlington Canyon on California’s Channel Islands. These grains were found in sediment layers corresponding to the beginning of the Younger Dryas period, which occurred around 12,800 years ago.

Researchers reported that the quartz grains display microscopic fractures, some of which contain melted silica. The study states that these features are consistent with exposure to extreme heat and pressure that exceed those produced by volcanic eruptions or human activities.

Hydrocode modeling was used in the research to simulate a low-altitude comet airburst, referred to as a “touchdown airburst.” According to the study, this type of event could generate the pressures and temperatures required to form the observed shocked quartz grains.

What the numbers show

• Three Clovis-era sites yielded shocked quartz grains
• The Younger Dryas began approximately 12,800 years ago
• The period of climate change lasted about 1,000 years

In addition to shocked quartz, other indicators of an impact event were found in the same sedimentary layers at these sites. These include platinum anomalies, meltglass, soot, nanodiamonds, and microspherules, according to the published findings.

The Younger Dryas is described as a sudden return to near–ice-age conditions that interrupted a previous warming trend after the Last Glacial Period. This climatic shift persisted for about a thousand years.

The hypothesis that a fragmented comet exploded above Earth’s surface at the onset of the Younger Dryas has been discussed in scientific literature since the early 2000s. Previous challenges to this idea have cited the absence of an impact crater and uncertainty about mechanisms for widespread airbursts.

The study’s authors state that the new shocked quartz evidence strengthens the argument that a cosmic airburst may have contributed to the extinction of megafauna and the decline of the Clovis technocomplex during the Younger Dryas onset.

* This article is based on publicly available information at the time of writing.