HOLOCENE GLACIER FLUCTUATIONS OF THE PEMBERTON ICEFIELD, SOUTHERN COAST MOUNTAINS, BRITISH COLUMBIA

Dendrochronology and radiocarbon dating of in situ and detrital wood are being utilized to date Holocene glacier fluctuations at the Pemberton Icefield. Fieldwork at 14 glaciers was carried out in the summers of 2012 and 2013. At least four glaciers advanced and overrode 250-yeard-old in situ forests around 6800 years ago. 4000-year-old detrital wood washing out of from beneath present-day glacier snouts has been found at three glaciers; at West Squamish Glacier these include tree trunks that were 350 years old and up to 40 cm in diameter, and thus much larger than any living trees near the present treeline. Several visited glaciers have stacked lateral moraines that contain 3100-yeard-old wood in distinct horizons, some of which are in situ. Little Ice Age maximum and recessional moraines were dated at most glaciers and indicate that maxima were reached between AD1690 and 1720. Glaciers of the Pemberton Icefield have retreated significantly since the end of the Little Ice Age; both the west and east arm of Squamish Glacier have retreated more than 5 km since around AD1700, and by ca. 500 m since 1982. The timing of events obtained thus far indicate a similar history than other glaciers in the Coast Mountains, and elsewhere in the world, and thus provide further evidence for global forcings of Holocene glacier fluctuations.