Quaternary glacier fluctuations in the Chigmit Mountains, Alaska

Fritschen, Margaret

Glaciers in the Chigmit mountains of south-central Alaska expanded and coalesced several times during the Late Pleistocene and left spectacular moarines in the Lake Clark region. These moraines were mapped and studied using relative-age dating techniques, and the associated paleoglaciers were reconstructed and equilibrium line altitudes (ELAs) were calculated in an effort to derive a pattern of climatic fluctuation for the area. Eight distinct late Pleistocene moraine groups were defined. Holocene moraines were also examined. Relative-age dating suggests taht the Holocene moraines are significantly different from all others, but no consistent differences were identified within the group of Pleistocene moraines. Paleo-glacer reconstructions and calculated ELAs produced a compelxt history of glacier fuctuation. Comparisons to the glacial sequence on the Alaska Peninsula described by Detterman (1996) suggest that the Kvichak, Iliamna, and Newhalen advances are represented by several moraine groups in Lake Clark region.