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Varves in Elk Lake are composed of seasonally deposited laminations of diatoms, calcite, aragonite, and layers enriched in Mn, Fe, organic matter, and clay and/or silt. The proportions of these components and the character of varve laminations changed systematically over the past 10,000+ years and define a post-glacial lake rich in calcium and manganese, a mid-Holocene prairie lake with sediments enriched in clay and silt, and a modern lake rich in Fe. Sequential changes in varve composition during the three phases of lake development are the result of a maturing lake and drainage basin and a systematic shift in airstream movements, accompanied by changes in precipitation, vegetation, and sedimentational responses to climatic forcing.

Changes in varve thickness between 3.8 and 8.0 ka are attributed to eolian processes and are believed to reflect changes in regional surface winds. Within this ~4000 year time window is a 2000 year interval when time series for Δ 14C (from tree rings) and varve thickness cross correlate and when both express periodicity at ~200 years, 40–50 years, and 20–25 years, supporting meteorological evidence that solar-geomagnetic events lead to changes in both cosmic particle flux and tropospheric winds. The Earth’s magnetic dipole moment reached its lowest value in the Holocene during the same 2000 year interval, suggesting that solar-geomagnetic events had a greater effect on the wind field when the Earth’s magnetic field was weak. A period of ~100+ years is weakly expressed in iron-rich varves during the past 3800 years, with a shift from cyclicity of ~100 years to 40–50 years between the Medieval Warm Epoch and the Little Ice Age.

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