FROM 1960 TO THE PRESENT: TRACKING YEAR-BY-YEAR CHANGES TO THE INTERNATIONAL COMMISSION ON STRATIGRAPHY’S GEOLOGIC TIMESCALE

Numerous authors have described the historical development of the International Commission on Stratigraphy’s (and International Geologic Congress’) Geologic Timescale. Still, a detailed review of nomenclature and dates has not yet been compiled. Here we present the historical development of the entire ICS Timescale through a visualization of yearly changes in radiometric dates, names, and GSSPs from the period starting in 1960 to the current year. Sources from official ICS timescale compilations/documents (annual reports, Episodes papers, etc.) were considered first unless proven unreliable. For radiometric dates, information was then sourced from widely accepted, non-affiliated timescale publications (Harland et al. 1964-1982, Cowie and Basset 1989, Holmes 1959, among many others). Finally, lesser-known papers were used (e.g., Dewey et al. 1970) if they were the only timescales published that year and were at least partly valid. The data collected has been put into a relational database accompanied by an animation that shows timescale changes on a yearly resolution. This animation and the accompanying data illustrate the complex changes that have occurred throughout the development of the timescale and address several common misconceptions (e.g., details surrounding the Quaternary debate). A more complete understanding of timescale historiography will inform future efforts on timescale construction, help avoid previous mistakes, and encourage more transparency and historical note-keeping.