Set in Stone: The Story of NACSN

The North American Commission on Stratigraphic Nomenclature, charged with the goal of promoting common standards in stratigraphic nomenclature and practise throughout North America, celebrated its 65th anniversary in December, 2011.

The roots of this organization go back to the 1930s, when a small group of geologists, concerned with the lack of uniformity in stratigraphic terminology and application of stratigraphic principles in different regions and professional sectors across the nation, set up a self-appointed Committee on Stratigraphic Nomenclature, and began the task of formulating guidelines that would be both useful and consistent. The resulting "Classification and Nomenclature of Rock Units," were published in the Bulletin of the Geological Society of America in 1933 (G.H. Ashley et al., vol. 44, pp. 423-459).

In 1941, R.C. Moore proposed that representatives from the Association of American State Geologists, American Association of Petroleum Geologists, Geological Society of America, U.S. Geological Survey and Geological Survey of Canada should form a permanent body to oversee standard stratigraphic practices. Following World War II, Moore revived discussion among the same groups, and In 1946, the American Commission on Stratigraphic Nomenclature became a reality with Moore as inaugural chairman and M.G. Cheney as vice-chairman. The Commission was later expanded to include representatives from other major geological organizations in Canada and Mexico, and changed its name to reflect its present pan-continental scope,  


The Commission’s chief publication is the North American Stratigraphic Code, (in PDF), with the current version dating to 2005. The Code serves as a guide to all stratigraphic practices throughout North America, and is foremost among the regional codes that influenced the nature, content, and stratigraphic philosophy of the International Stratigraphic Guide. Although all changes to the Code are finalized by the Commission, the terms of Article 21 allow any geoscientist to submit proposals for changes or additions (see “Contact us”).

The Commission is continually updating the 2005 Code in response to new developments, with occasional revisions to entire sections. A recently completed program to improve the clarity of the Code included a complete revision of the "On Biostratigraphic Units" section. Discussions for emending the "Hydrostratigraphic Units" section is in progress and extensive discussions are planned on the relationship between "Allostratigraphy" and "Sequence Stratigraphy" - including whether there should be a separate "Sequence Stratigraphy Units" section.

To better serve the North American community, the Instituto de Geologia de Mexico published the Code in Spanish in 2010.

In 2009, the journal Stratigraphy  published a special issue, Set in Stone: The Work of the North American Commission on Stratigraphic Nomenclature, that offers a comprehensive view of the Commission. Chapters include a full history of the Commission and the successive stages in development of the Code, advice on its use, discussions of the theoretical and practical issues of time and rock units that are addressed in the Code, and the articles of procedure.