https://www.scinexx.de/news/geowissen/ein-golden-spike-fuer-den-schneeball-erde/
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4. Searching for the Golden Spike: The Geologic Proof
◦ To formalize the epoch, geologists seek a "golden spike" (GSSP)—a physical marker appearing globally in the rock record at the same time.
◦ Candidates for this marker include plutonium-239 from nuclear testing (starting in 1945), synthetic plastics, soot from fossil fuels, and even the global spread of the broiler chicken.
