Northeastern Section–41st Annual Meeting (20–22 March 2006)

Paper No. 4
Presentation Time: 1:00 PM-4:00 PM


LODDENGAARD, Kathryn and CURTIN, Tara M., Geoscience Department, Hobart & William Smith Colleges, 300 Pulteney St, Geneva, NY 14456,

A paleohydrological study of two ~2 m long piston cores collected from the littoral zone of northern Seneca Lake, one of 11 Finger Lakes in New York, revealed distinct changes in lithology during the Holocene. We examined the texture, magnetic susceptibility, and organic matter and carbonate content of these cores to determine relative lake level fluctuations.

Both cores penetrated pink, laminated proglacial silty clays that are characterized by low organic matter, carbonate, and fossil content. Overlying the proglacial clays are light to dark gray silt that ranges from 13.5 to 72 cm in thickness. This unit has an intermediate to high carbonate (20-40%) and low organic matter (<5%) abundance, and low fossil (ostracodes, bivalves, and gastropods) content. Spikes in magnetic susceptibility correspond to an increase in sand abundance.

Stratigraphic, carbonate abundance, and grain size trends point to several small-scale changes in lake level. We interpret finely laminated, carbonate-rich (30-40%), fine-grained (silt) sediment to reflect deeper water conditions. Homogenous, bioturbated, coarser-grained, sand-rich mud reflects shallower water conditions. Similar to other Finger Lakes, these two cores from Seneca Lake show at least three changes in lake level over the past ~14 ka. Previous studies show that Holocene lake level records from eastern Canada, other Finger Lakes, and southern New England are inconsistent with each other, suggesting high variability in the dominant air masses.