Late-Holocene environmental and climatic conditions were reconstructed from diatom assemblages in sediment cores from four western Montana lakes: Crevice Lake, Foy Lake, Morrison Lake, and Reservoir Lake. The lakes show synchroneity in timing of shifts in diatom community structure, but the nature of these changes differs among the lakes. Two of the sites provide highly resolved records of hydrologic balance, while the other two stratigraphic sequences primarily record temperature impact on lake thermal structure. All four lakes show significant change in five discrete intervals: 2200-2100, 1700-1600, 1350-1200, 800-600, and 250. cal. yr. BP. The similarities in the timing of change suggest overlying regional climatic influences on lake dynamics. The 800-600. cal. yr. BP shift is evident in other paleorecords throughout the Great Plains and western US, associated with the transition from the Medieval Climate Anomaly to the Little Ice Age. Large-scale climatic mechanisms that influence these lake environments may result from atmospheric circulation patterns that are driven by interactions between Pacific and Atlantic sea-surface temperatures, which are then locally modified by topography.
|Original language||English (US)|
|Number of pages||12|
|State||Published - May 2012|
Bibliographical noteFunding Information:
We would like to thank the editor, Wyatt Oswald, and the anonymous reviewers whose comments greatly improved this manuscript. Eric Grimm obtained the cores from Morrison and Reservoir lakes and the radiocarbon dates for these sites. C. Whitlock, W. Dean, J. Stone, L. Stevens, M. Power, J. Campbell, J. Rosenbaum, K. Pierce, L. Doner, J. Honke, and G. Skipp assisted with coring Crevice and Foy lakes. Funds from NSF ( EAR-0816576 , EAR9905262 ), Yellowstone National Park , and the USGS supported this research. We would also like to thank Jeffrey Stone and Karlyn Westover for their comments and suggestions. Pat Bartlein designed and produced the data analysis used in Figure 1 B.
Copyright 2012 Elsevier B.V., All rights reserved.
- Little Ice Age
- Medieval Climate Anomaly
- Western North America