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Sediment cores extracted from three lake basins in Northeast Ohio reveal a marked transition from organic rich late Holocene muds to sediments richer in clastics in two of the basins, while the third and smallest lake basin contained no such transition. Analyses of sediment cores from Long Lake were conducted at the LacCore facilities in Minneapolis, Minnesota and revealed an increase in magnetic susceptibility and gamma density measurements, which are consistent with an influx of eroded soils into the aquatic system. Radiocarbon dating of material gathered from the noted transition dates to the early 19>th) century. The drainage basins range in size from Odell Lake, which is 52 km>2) to Long Lake, at 6 km>2) to...
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In Alaska, lichenometry continues to be an important technique for dating late Holocene moraines. Research completed during the 1970s through the early 1990s developed lichen dating curves for five regions in the Arctic and subarctic mountain ranges beyond altitudinal and latitudinal treelines. Although these dating curves are still in use across Alaska, little progress has been made in the past decade in updating or extending them or in developing new curves. Comparison of results from recent moraine-dating studies based on these five lichen dating curves with tree-ring based glacier histories from southern Alaska shows generally good agreement, albeit with greater scatter in the lichen-based ages. Cosmogenic surface-exposure...
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This review summarizes forefield and lacustrine records of glacier fluctuations in Alaska during the Holocene. Following retreat from latest Pleistocene advances, valley glaciers with land-based termini were in retracted positions during the early to middle Holocene. Neoglaciation began in some areas by 4.0 ka and major advances were underway by 3.0 ka, with perhaps two distinct early Neoglacial expansions centered respectively on 3.3–2.9 and 2.2–2.0 ka. Tree-ring cross-dates of glacially killed trees at two termini in southern Alaska show a major advance in the AD 550s–720s. The subsequent Little Ice Age (LIA) expansion was underway in the AD 1180s–1320s and culminated with two advance phases respectively in the...
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Glacier mass-balance reconstructions provide a means of placing relatively short observational records into a longer-term context. In western North America, mass-balance records span four to five decades and capture a relatively narrow window of glacial behavior over an interval that was dominated by warming and ablation. We use temperature- and moisture-sensitive tree-ring series to reconstruct annual mass balance for six glaciers in the Pacific Northwest and Alaska. Mass-balance models rely on the climatic sensitivity of tree-ring chronologies and teleconnection patterns in the North Pacific. The reconstructions extend through the mid to latter portions of the Little Ice Age (LIA) and explore the role of climate...
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