Tephras are often used in paleolimnology and other stratigraphic applications as a chronostratigraphic marker. Where analytical errors in radiocarbon or other dating methods make precise comparison between sites difficult, tephras provide an absolute stratigraphic reference that can be used to assess the relative ages of events across a region. Applications of tephrochronology typically make the assumption that a tephra is deposited at what was the top of the stratigraphic sequence at the time of deposition, and that the contact between the tephra and underlying sediments is an isochron. This paper presents evidence from two lakes in western Canada which suggest that tephras may be very mobile within the sedimentary column, particularly [...]
