Evaluating the Concept of a Global “Last Glacial Maximum” (LGM): A Terrestrial Perspective
The concept of a Last Glacial Maximum (LGM) dominates the Quaternary literature and ideas associated with the last glacial cycle (Weichselian, Wisconsinan, Valdaian Stage, Marine Isotope Stages [MIS] ca. 5d-2). However, neither its meaning nor its stratigraphic definition is well defined. This is despite recent efforts to formalise the term and to define the event or period within time (e.g., Mix et al. 2001). The prevailing view associates the LGM with the maximum extent of ice on land and a corresponding low-stand in global eustatic sea levels—the lowest of the last glacial cycle. However, the global ice signal is based on the marine isotope record and on land the LGM is not clearly represented in glacier records (Hughes et al. 2013). The former is a composite signal and as such provides no indication of the spatial and temporal variability of glaciers on Earth’s surface.
KeywordsLGM Last glacial maximum Stratigraphy Chronozone Chron Event Climatostratigraphy Asynchronous
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