Evolving Norms in Stratigraphy: Historical Perspectives on the Formalization of the Anthropocene

Current discussions on the Anthropocene have generated a wide range of high-resolution stratigraphic data, including sedimentary, geochemical, and biological signals that may serve as potential markers of recent planetary change. Alongside these developments, important questions remain regarding how such signals should be evaluated, compared, and integrated within the formal chronostratigraphic framework. This paper aims to contribute to these discussions by examining the role of evolving norms in stratigraphy. Here, “norms” refer to the standards, criteria, and shared expectations that guide decisions about what counts as a valid marker, how boundaries are defined, and which signals are prioritized in defining chronostratigraphic units. Drawing on historical case studies – the nineteenth-century Devonian controversy and the twentieth-century debates over the Silurian-Devonian boundary that culminated in the development of the Global Boundary Stratotype Section and Point (GSSP) – this paper shows that stratigraphy has repeatedly involved reconfigurations of what counts as stratigraphically valid evidence in response to changing scientific and institutional demands. In the Devonian case, tensions between lithological and biostratigraphic methodologies were renegotiated as lithological approaches proved difficult to apply consistently beyond local contexts. This led to the establishment of the Devonian System and to the increasing institutional prioritization of biostratigraphic criteria for regional and global correlation. In the twentieth century, the formalization of the GSSP framework marked a further shift in priorities. As stratigraphy became increasingly global and institutionalized – particularly with the establishment of the International Union of Geological Sciences (IUGS) and the development of a standardized chronostratigraphic framework and guidelines – greater emphasis was placed on criteria that ensure global correlatability and stratigraphic stability. Stratigraphic practice accordingly moved away from identifying presumed natural breaks toward the use of agreed reference points, such as First Appearance Datums (FAD), that enable consistent global correlation. These cases demonstrate that the acceptance and integration of stratigraphic evidence depend not only on empirical validity but also on evolving criteria shaped by the practical and conceptual demands of stratigraphy at a given time. Building on these precedents, this paper suggests that the Anthropocene discussion can be productively approached not only as a search for stratigraphic signals but also as a process of clarifying and coordinating the criteria by which such signals are evaluated. By making these criteria explicit, this study offers a complementary perspective that facilitates comparison between different forms of evidence – including radionuclides, technofossils, and biostratigraphic indicators – and highlights how their relevance depends on shared, but evolving, stratigraphic expectations.