New meteorite fragments reveal the scale of Ice Age glaciers

New fragments from the Twannberg meteorite field in the Bernese Jura are providing fresh insights into the glaciers of the penultimate Ice Age and how asteroids break apart in the atmosphere, SRF reports.

The meteorite field, discovered above Lake Biel in 2016, is one of Europe’s most significant. Hundreds of fragments from an exceptionally rare iron meteorite were found on Twannberg and Mont Sujet.

About 175,000 years ago, during the penultimate Ice Age, the object is believed to have exploded as it entered Earth’s atmosphere. The estimated four to 20 metre wide body weighed at least 250 tonnes and scattered debris over what is now Mont Sujet.

Farmer Margrit Christen discovered the first fragment in 1984 while collecting stones in a field. The 15 kilogram piece was followed by many more finds.

Today, more than 2,200 fragments have been recovered, compared with about 400 a decade ago, according to geologist and expedition leader Beda Hofmann of the Natural History Museum Bern. He continues to search the six kilometre long field with a metal detector.

The search requires a permit from the responsible archaeological service. Hofmann said it was laborious, with the detector usually finding modern waste such as aluminium foil, nails and old rifle cartridges. Finding a genuine meteorite fragment after days of searching, he said, brings a feeling of “happiness”.

Some fragments found in 2026 were demonstrably transported by glaciers. Because they were discovered at higher elevations than earlier pieces, they offer clues about the enormous ice masses of the penultimate Ice Age, when the Swiss Plateau was buried beneath an ice sheet several kilometres thick.

The Twannberg data could also help scientists better understand how asteroids behave as they enter the atmosphere. This may eventually allow more precise calculations of the danger posed by smaller celestial bodies on collision courses with Earth.