35-14 New Insights on Farmington River Delta Deposits and the Drainage of Glacial Lake Hitchcock in Southern New England

Session: Ice sheets, glaciers, and landscapes, oh my! (Posters)

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Abstract:

The drainage history of Glacial Lake Hitchcock has been studied for over two centuries. Previous investigations have integrated radiocarbon (¹⁴C) dating, optically stimulated luminescence (OSL) exposure ages, and the North American Varve Chronology (NAVC) to refine the lake’s temporal framework. This effort is complicated by disruptions to the record caused by fluctuating lake stages, driven by the evolution and failure of sediment dams within the lake basin. The Farmington River delta was initially established as an ice-marginal delta along the western shore of Glacial Lake Hitchcock opposite the Scantic River delta in central Connecticut, approximately 17.9 cal ka–17.6 cal ka. Previous work and mapping suggest three separate phases of deposition recorded for this delta, each corresponding with changes in lake levels relative to the sediment dam at Rocky Hill (CT). In this study, we present the results of an investigation focused on a new outcrop, sediment cores, and GPR data collected for the eastern-most portion of the Farmington delta that was active in the later stages of its development. Stratigraphy at the site is consistent with braided rivers carrying silt, sand and fine gravel in the topset environment of the delta (data is focused on the upper 3 m of sediments at the site). Numerous large paleochannels are observed in GPR data, and field observations confirm that these channels are filled with medium-fine sand. We interpret these channels and sand fill as being related to local, small scale fluctuations of the lake level, perhaps due to seasonal changes, and not the regional lake levels (stable and then post-stable) argued for in the mapping of Stone et al., (2015). Representative samples recovered from the paleochannel will be submitted for OSL and ¹⁴C analysis pending further funding. These integrated site observations and geochronology results are expected to refine the current framework of glacial Lake Hitchcock, further resolving the late-stage sedimentation and drainage history.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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