OPTICAL DATING SEDIMENTS FROM COASTAL BRITISH COLUMBIA: SUCCESSES, CHALLENGES, AND PLANS FOR THE FUTURE

We review geochronological data obtained from four localities on the coast of British Columbia (BC), Canada: Hunter and Calvert islands of the Central Coast, and Quadra and Savary islands of the Discovery Islands region further south. The luminescence characteristics of samples used for optical dating, including quartz and feldspar optical signals, their response to laboratory irradiation and heat treatments, and the fading rates of feldspar, are discussed. Where possible, ages obtained using both optical and radiocarbon dating methods at the same site are compared. At some sites, we observe apparent inconsistencies between optical and radiocarbon ages; some of these can be explained by site formation processes (e.g., mixing between old and young sediments, the re-working of organic material, bioturbation and pedogenesis). However, potential issues with our optical dating procedures, such as inadequate delay times during fading measurements, or non-reproducible fading measurements, cannot be ruled out. We discuss initial results of our ongoing investigation into the robustness of our optical dating procedures on coastal deposits in BC, and suggest future avenues of research.