[taylorportman]

I wonder if there is a common substance that could be scanned for historical interactions - like some salt flats.. that might preserve, like film, a history of energetic anomalies.

[eesmith]

One such is a Miyake event. https://en.wikipedia.org/wiki/Miyake_event

> an observed sharp enhancement of the production of cosmogenic isotopes by cosmic rays. It can be marked by a spike in the concentration of radioactive carbon isotope 14C in tree rings, as well as 10Be and 36Cl in ice cores, which are all independently dated.

Wood and ice are pretty common. :)

I don't know if there are other examples.