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Meteorite Mementos

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Tektites from the collections of the American Museum of Natural History

A crater’s scar on the landscape is the most recognizable remnant of a meteorite impact. But meteorites have left other, much smaller markers of their presence on the surface of the Earth: splash droplets called tektites.

During a meteorite impact, “the ground and the object are trying to occupy the same space instantaneously,” says Denton Ebel, curator in the Museum’s Department of Earth and Planetary Sciences. “It’s an explosion at that point.”

The force of the impact is so strong that some parts of the Earth’s surface are not just cast into the air but are heated into molten rock that behaves like liquid glass. As droplets of the melt fly through the atmosphere, they are swiftly quenched into solids, often retaining their droplet form. The Museum has hundreds of these specimens, which range in scale from mere millimeters to the size of a fist.

Some of the most prized tektites are the unique bottle-glass green Moldavites from the Czech Republic. Moldavites were formed by the massive impact 15 million years ago in what is now Germany. The impact left the 16-mile-wide Ries crater and scattered bright green glass droplets across Eastern Europe. This spread is what geologists call a “strewn field,” which can cover hundreds and even thousands of miles. Over the years, tektites were buried by sediments, to be later revealed by erosion or human efforts.

Though widespread around impact sites, tektites are relatively ephemeral geologic specimens. “Glass doesn’t last that long in the geological record,” says Ebel, explaining that glass, even glass made from molten rock, will start to break down after a few million years.

Tektites eventually develop pitted surfaces or break down entirely. But despite their short lives, they remain beautiful physical reminders of Earth’s tempestuous relationship with space.

This story originally appeared in the Summer issue of Rotunda, the Member magazine.