Tuesday, July 11, 2023


Couplets of organic matter capped by calcite precipitated each summer in alkaline surface waters of Crawford Lake accumulate undisturbed below the chemocline of this 23-m-deep meromictic lake in Ontario, Canada.  This records fallout from nuclear and thermonuclear testing, with strong activity during 1952–1953 CE and levelling associated with the fluctuations in yield, notably testing cessation between November 1958 and February 1961. 

The Anthropocene Working Group of the Subcommission on Quaternary Stratigraphy is working towards formally defining an Anthropocene epoch/series, and its associated age/stage commencing in the mid-20th century.  

Given the intensity, magnitude, planetary significance and global isochroneity of the [observed effects], it provides a suitable level for recognition of the base of the Anthropocene as a series/epoch.  The chronostratigraphic Anthropocene, defined in strict accordance with ICS approved nomenclature and procedures, provides a clear and stable meaning to stratigraphic use of the term "Anthropocene".

-- Francine MG McCarthy, et al, "The varved succession of Crawford Lake, Milton, Ontario, Canada as a candidate Global boundary Stratotype Section and Point for the Anthropocene series", 4th International Congress on Stratigraphy 11-13 July 2023.  This paper asserts that measureable nuclear fallout in the strata beneath Crawford Lake provides evidence of the geological impact of mankind, marking the start of a new geological epoch dubbed "Anthropocene" (recent age of man)

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