A High-Resolution Record of Climatic Change in Elk Lake, Minnesota for the Last 1500 Years

A High-Resolution Record of Climatic Change in Elk Lake, Minnesota for the Last 1500 Years

1994

Earlier investigations of varved sediments from Elk Lake, Minnesota (Fig. 1) based on integrated 50-year samples at 100-200-year intervals illustrated the sensitivity of Elk Lake to climatic change (Bradbury and Dean, 1993). Varve thickness measurements demonstrated the rapid (interannual) nature of climatic variation during parts of the Holocene (Dean and others, 1984; Bradbury and Dean, 1993). Studies of ostracodes (Forester and others, 1987), chironomids (Stark, 1976),and geochemical and mineral properties (Dean, 1993) showed that rapid (decadal to centennial), high amplitude changes in sediment components occured during the time interval of 10,000+ to 4,000 years ago. In contrast to these early and middle Holocene changes in sediment characteristics, the Elk Lake record for the past 4,000 years is more stable, but nevertheless shows lower amplitude variations in many sediment parameters over the last few millennia that testify to significant climatic changes at scales of human importance. In this report we present the initial results of analyses of contiguous samples, each a composite of about five years, to document a high-resolution paleolimnological history of the past 1500 years in Elk Lake. These results chronicle past climatic changes in the north-central US throughout the period of time that encompasses the Little Ice Age, the Medieval Warm Period, distinctive episodes of reduced solar activity (the Maunder and Sporer Minima), and the impact of European settlement and exploitation of the region after AD 1890. The cyclicity of these changes suggests forcing mechanisms related to solar activity and its influence on the strength and direction of near surface wind fields at mid-latitudes in the Northern Hemisphere.Figure 1

U.S. Department of the Interior
U.S. Geological Survey

U.S. Geological Survey

131

Hydrology

Climate change

Elk River

1990-1999

No

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