LITTLE ICE AGE GLACIAL ACTIVITY IN THE LILLOOET ICEFIELD AREA, SOUTHERN BRITISH COLUMBIA COAST MOUNTAINS

Numerous glaciers spill into tributary valleys from the Lillooet Icefield in the southern British Columbia Coast Mountains. All of these glaciers show evidence for significant historical retreat and downwasting. Our paper describes the result of field investigations at two glacier forefields where nested terminal and lateral moraine complexes demarcate multiple pulses of glacier expansion interspersed with periods of glacier retreat during the Little Ice Age (LIA). At Tchaikazan Glacier in Ts'yl-os Provincial Park, lichenometric and radiocarbon dating describe moraine building events in the 15th to early-16th centuries, the late-17th century and the mid-19th century. At Bridge Glacier in the headwaters of the Bridge River valley radiocarbon dating of dendroglaciologic samples shows that LIA glacier expansion was underway by ca. 700 14C years BP. Lichenometric investigations at eight terminal and lateral moraine complexes led to the recognition of early-LIA moraine-stabilization events during the late 13th to early 14th centuries, with subsequent LIA moraine-stabilization events recorded in the mid-15th, early-16th, mid- to late-17th, early-18th, mid- to late-19th, and early-20th centuries. The synchronicity of moraine-building episodes in the Lillooet Icefield area suggests they correspond to a long-term glaciological response to persistent climate-forcing mechanisms.