The Geologic Time Scale 2020

Felix Gradstein is Professor Emeritus at Oslo University, Norway and visiting Research Fellow, University of Portsmouth, UK. From 2000 to 2008, he was chair of the International Commission on Stratigraphy. Under his leadership major progress was made with the formal definition of chronostratigraphic units from Precambrian through Quaternary. For his fundamental work concerning the Geologic Time Scale, geochronology in general, quantitative stratigraphy and micropaleontology, the European Geosciences Union awarded him in 2010 the Jean Baptiste Lamarck Medal. He is Chair of the Geologic Time Scale Foundation and teaches courses in quantitative stratigraphy and the geologic time scale. JAMES OGG (Professor at Purdue University, Indiana, USA; now retired/adjunct) is also currently a visiting distinguished professor at Chengdu University of Technology and at China University of Geoscience (Wuhan). He served as Secretary General of the International Commission on Stratigraphy (2000-2008), and currently is executive director of the Geologic TimeScale Foundation and coordinator of TimeScale Creator service (https://timescalecreator.org/). His Mesozoic Stratigraphy Lab group has worked on aspects of climate cycles, magnetic polarity correlations and integration of stratigraphic information. Their TimeScale Creator array of visualization tools and extensive databases in global and regional Earth history was used to generate many of the diagrams in this book. MARK SCHMITZ is Professor of Geochemistry at Boise State University, Idaho, USA, and has extensive research interests in the development and application of radiogenic isotope geochemistry and high-precision U-Pb geochronology to problems of Earth systems evolution. He has been an active member of the Earth Time community and was co-editor and author for the Geologic Time Scale 2012. He seeks to enrich the radioisotopic calibration of the time scale through targeted dating of stratigraphically important volcanic event beds and the construction of robust chronostratigraphic models through geologic time. His extensive database with over 300 standardized radiogenic isotope ages (mainly U/Pb and Ar/Ar) is vital to this book. GABI OGG applied micropaleontology to Jurassic-Cretaceous correlations before concentrating on public outreach in geosciences. She coordinated the extensive array of graphics in this book, and is the webmaster for the Geologic TimeScale Foundation (https://timescalefoundation.org) and for the TimeScale Creator visualization and database suites (https://timescalecreator.org). In addition to co-authoring the Concise Geologic TimeScale (GTS2016) and The Geologic Time Scale (GTS2012) books, she has produced numerous posters and time scale cards for public audiences.