HR: 1330h
AN: PP42A-0870    [PDF]
TI: Evidence of Multiple Highstands and Lowstands During the Holocene in Seneca Lake, New York
AU: * Baker, A P
EM: ABaker@hws.edu
AU: Curtin, T M
EM: Curtin@hws.edu
AB: The mid-Holocene Hypsithermal ($\sim$8-$\sim$4 ka) is a well-known global warm period. Northern Hemisphere summer temperatures may have been 2-$4\deg$C warmer than present. Previous Holocene lake level reconstructions from North America indicate arid conditions existed between $\sim$9 and $\sim$6 ka. However, the timing of relative lake level lowstands in the midwestern United States does not correlate with the timing of lowstands in the eastern United States. In the Finger Lakes region of central New York State, the highest relative lake levels occurred during the Hypsithermal. For example, Cayuga Lake highstands occurred at 8.8, 7.0, and $\sim$5 ka and within Owasco Lake at 10.5 and 6.9 ka (Mullins 1998, Dwyer et al. 1996). The focus of this research is to establish the timing of lake level fluctuations in Seneca Lake, another Finger Lake, to investigate whether these fluctuations are local or regional phenomenon. A transect of six sediment cores were collected from the littoral to the profundal zone of Seneca Lake to determine the history of relative lake level change. Cores were analyzed for magnetic susceptibility, described, photographed, and sampled every 2 cm for total organic matter and carbonate content analyses. Temporal control of lake level fluctuations will be established by accelerator mass spectrometer radiocarbon dates of terrestrial organic matter and gastropods. The littoral zone cores consisted of early to mid-Holocene laminated olive gray and black medium-grained sand with pebble lags overlain by marl ($>$ 30% CaCO$_{3}$) with abundant gastropod lags ({\it Lyminaeidae palustris, Planorbidae Helisoma anceps}, and {\it Planorbidae valata tricarinata}) and rare pebble lags. Profundal zone cores contained proglacial pink clays overlain by Holocene mm-scale olive gray and black laminations of fine-grained sand and silt. Cores were correlated based on their carbonate and organic matter content. The shell and pebble lags were used as the primary indicators of lowstands. Laminated olive gray and black sand in littoral zone cores are interpreted to be intervals of high relative lake levels. Initial results indicate at least five small amplitude lowstands as well as one large amplitude highstand.
DE: 1845 Limnology
DE: 3344 Paleoclimatology
DE: 9350 North America
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting