Ancient plants 'frozen in time' by space impacts

Ancient plant material has been preserved in the glass formed by asteroids hitting the Earth, scientists report.

These electron microscope images show the preserved
 fragments of plants from Argentina
The "frozen in aspic" appearance of what are apparently fragments of grass is spectacular enough.

But a team writing in Geology journal says that delicate organic chemicals have also been conserved inside.

Incredibly, the searing heat generated by the impacts was responsible for the remarkable preservation.

The findings could even point to a new way of searching for past life on Mars.

The impact glasses examined in this study come from the Pampas of Argentina and have a range of dates under 10 million years old - in the Miocene and Holocene periods.

When objects from space slam into the ground they melt the target rocks. Hot material gets thrown out of the craters and, in these cases, it captures and traps shards of vegetation.

Scientists say the plant remains look very similar to the Pampas grass that still grows in the region today.

Prof Peter Schultz, from Brown University in Rhode Island, US, presented the work at last month's Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.

In their scientific paper, the Brown University geologist, R Scott Harris, Marcelo Zarate and others write that while space collisions can destroy life on local or global scales, "it can also preserve components of the local biology present at the time of impact".

Prof Schultz told BBC News: "It turns out the composition of the plant material is very similar to the composition of the impact glass itself.

"It was very rapidly transferred from one thing to the other, likely due to the rapid and high heat that boiled off that plant material and replaced it with glass," Prof Schultz explained.

- BBC.com


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