Glass from the Sky: Tektites, Museums, and Hidden Craters

Tektites are fragments of natural glass that form when a high-speed meteorite impact melts and ejects surface rocks; as they re-enter the atmosphere these droplets cool into aerodynamic shapes. The vast Australasian strewn field, which stretches from Southeast Asia to southern Australia, has been dated at roughly 0.79 to 0.80 million years, yet the source crater remains elusive. Some researchers have proposed that the impact site is buried beneath the Bolaven volcanic field in southern Laos, and this hypothesis has been supported by gravity anomalies and young lava ages; nevertheless, drilling would be needed to confirm the interpretation.

Across the globe tektite ages span a wide range, from a few hundred thousand years to more than thirty million, and certain deposits are thus far older than the Australasian event. Darwin glass, which occurs in southwest Tasmania and is associated with Darwin Crater, yields argon-argon ages near 816,000 years and displays chemical and textural differences that suggest it formed in a distinct impact. Other strewn fields, such as the North American and Libyan fields, date to tens of millions of years and illustrate that multiple major impacts have produced glassy ejecta over Earth history.

Moreover, museum collections, where specimens are catalogued and curated, play a crucial role because they preserve material that can be reanalyzed as methods improve. If researchers combine detailed chemical fingerprints with radiometric ages and contextual geology, they can often distinguish pieces that were made by different impacts even when the glass looks similar. Not only do museums conserve rare samples for scientists, but they also allow the public to see evidence of past cosmic events.