Late Pleistocene and Holocene glaciation of the Fish Lake valley, northeastern Alaska Range, Alaska

We reconstructed a chronology of glaciation spanning from the Late Pleistocene through the late Holocene for Fish Lake valley in the north-eastern Alaska Range using Be surface exposure dating and lichenometry. After it attained its maximum late Wisconsin extent, the Fish Lake valley glacier began to retreat ca. 16.5 ka, and then experienced a readvance or standstill at 11.6 0.3 ka. Evidence of the earliest Holocene glacial activity in the valley is a moraine immediately in front of Little Ice Age (LIA) moraines and is dated to 3.3–3.0 ka. A subsequent advance culminated at ca. AD 610–900 and several LIA moraine crests date to AD 1290, 1640, 1860 and 1910. 10 Our results indicate that Be dating from high-elevation sites can be used to help constrain late Holocene glacial histories in Alaska, even when other dating techniques are unavailable. Close agreement between Be and lichenometric ages reveal that Be ages on late Holocene moraines may be as accurate as other dating methods. Copyright # 2009 John Wiley & Sons, Ltd.