EES Departmental Seminar: 2024-2025 GAC Logan Lecture
Dr. Sandra M. Barr
Professor Emerita
Department Earth and Environmental Science, Acadia University
EES (adjunct)
Title: 2024 Geological Association of Canada Logan Medallist Lecture: Geological studies in the northern Appalachian orogen – how we got to where we are
Abstract: The northern Appalachian orogen played a pivotal role in early geological interpretations of mountain belts. Its 100-year reign as the “type area” for the Hall-Dana geosynclinal theory abruptly changed with the “plate tectonic revolution” of the 1960s. Tuzo Wilson’s classic 1966 paper that posed (and answered) the question “Did the Atlantic Close and Then Reopen” led to the modern view of global tectonics based on the “Wilson cycle”. In retrospect, these early ideas about mountain-building were much hindered by lack of factual details. The 1978 map of the Appalachian orogen compiled and hand-drawn by Harold Williams and his students at Memorial University in Newfoundland is an outstanding example of geological artwork that led the way to a new focus on tectonic elements and along-orogen correlations that still form the essence of our current models. However, those correlations are now supported by an abundance of geological information collected steadily during the last decades of the 20th century and then accelerated by technological advances during the past 25 years. Among all the techniques developed in those years, arguably the most significant for global geoscience was the development of accurate and precise absolute dating techniques, especially U-Pb dating of zircon, and the construction of the current International Chronostratigraphic Chart. Appalachian studies now cover a spectrum from small areas investigated in detail to orogen-wide and global-scale interpretations that track Appalachian components back to their origins. The new knowledge has resolved many of the questions that were being asked in the 1970s when I began working in the Appalachians but also not surprisingly, have produced many more questions. This presentation is a personal perspective on the evolution of our understanding of northern Appalachian geology and the meandering path that led to where we are now.
Time
Location
Milligan Room, B-8007 8th Floor Biology/EES wing of the LSC
Additional Information
Meet the lecturer: COFFEE and COOKIES in B-3078 at 10:45 am