Mendenhall Postdoctoral Research Seminar and
Eastern Geology and Paleoclimate Science Center Seminar
Benjamin Hardt – USGS, Reston, VA
When: Tuesday, May 13, 2014 – 12 Noon
Where: National Center, Room 1C400 (Visitor Center)
Oh Shenandoah! 80,000 Years of Climate Change in Virginia’s Great Valley
Rapid climate change events such as the Younger Dryas, Dansgaard-Oeschger (D/O) events and Heinrich stadials are a prominent feature of climate during the last glacial period. Corresponding to large temperature changes in Greenland and the North Atlantic, these abrupt shifts have notable consequences for European temperatures, the Asian summer monsoon, and South American precipitation. Very little is yet known about the extent of variability associated with these events in the eastern United States. A precisely dated record from two stalagmites collected from Grand Caverns in Grottoes, Virginia, provides strong evidence of the Younger Dryas and earlier D/O events impacting the eastern United States. While these events may be associated with regional temperature change, the stalagmite record likely represents a more direct response to changes in the composition of annual recharge. Available drip water data indicate minimal seasonal variability in δ18O, suggesting mixing times of ~12 months or longer. Changes in the seasonal balance of precipitation between winter- and summer-dominated regimes could explain the observations, although additional study is needed. The strong expression of millennial events in δ18O from the Grand Caverns stalagmites demonstrated by wavelet analysis of the time series contrasts with results from West Virginia, which show minimal variability at millennial scales, and large changes associated with orbital forcing. The stronger expression of millennial events at Grand Caverns is likely due to its position on the east flank of the Appalachians, allowing a greater contribution of Atlantic moisture, particularly during winter months.
Topic: Mendenhall/EGPSC Seminar-Ben Hardt
Date: Tuesday, May 13, 2014
Time: 11:30 am, Eastern Daylight Time (New York, GMT-04:00)
Meeting number: 714 367 066
Meeting password: EGPSC
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