Alpine Glaciation on Baffin Island over the Last Millennium

Abstract:

In the Northern Hemisphere, moraines deposited by mountain glaciers during the Little Ice Age (LIA) typically represent the largest extent of glaciers during the late Holocene. Yet in some settings, pre-LIA moraines are preserved offering a unique opportunity to develop longer chronologies of late Holocene glacier change; in turn these chronologies can be used to assess spatio-temporal patterns of glaciation and their associated climatic driving mechanisms. Unfortunately, determining absolute ages for late Holocene moraines in the Arctic has proven difficult. Lichenometry has often been used to 1) broadly constrain the timing of moraine abandonment, and 2) correlate moraines between valleys, whereas in other cases fresh (unvegetated) moraines are casually ascribed to the LIA. Although fresh moraines fronting modern glacier snouts were undoubtedly deposited sometime during the last few hundred years, direct and precise ages for these moraines are scarce. However, recent advancements in ¹⁰Be surface exposure dating now allow for robust late Holocene glacier chronologies in some Arctic settings. We present a well-resolved ¹⁰Be-based record of glaciation from north-central Baffin Island and combine this chronology with a previously published record of ice-cap expansion to develop a holistic view of glaciation on Baffin Island over the last millennium. A prominent feature of our record is the extended state of glaciers during the Medieval Warm Period.