35-4 Concentrations of Be-10 in Deeply Quarried New England Glacial Sediment Suggest Ineffective Average Erosion and Sediment Transport by the Laurentide Ice Sheet

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

Poster Booth No.: 37

Presenting Author:

Authors:

Faust, Kira¹, Bridges, Aether², Thompson, Beck³, Cohen, Julia⁴, Burke, Madisyn⁵, Schmidt, Amanda H.⁶, Corbett, Lee⁷, Larson, Izzy⁸, Hulbert, Josh⁹, Caffee, Marc¹⁰, Bierman, Paul R.¹¹

(1) Geoscience, Oberlin College & Conservatory, Oberlin, , (2) Oberlin College & Conservatory, Oberlin, , (3) Oberlin College & Conservatory, Oberlin, , (4) Oberlin College & Conservatory, Oberlin, , (5) Oberlin College & Conservatory, Oberlin, , (6) Oberlin College & Conservatory, Oberlin, , (7) University of Vermont, Burlington, , (8) University of Vermont, Burlington, , (9) University of Vermont, , (10) Purdue University, , (11) University of Vermont, ,

Abstract:

The Laurentide Ice Sheet (LIS) covered much of the Northern Hemisphere during the Last Glacial Maximum (LGM). Two centuries of existing research suggests that there are places in New England where glacial erosion was effective, as indicated by glacially molded forms and U-shaped valleys, and places where it was not. For example, weathered rock, exposures of saprolite, and presence of the Miocene fossiliferous Brandon Lignite preclude deep glacial erosion where they are found. 

 

Thus, there remains significant uncertainty in how effectively the LIS eroded New England’s landscape, and transported sediment generated by that erosion, toward the ice sheet margin.

 

To address this knowledge gap, we collected samples of sand-sized glacial sediment (ice contact stratified drift) from depths > 5m in gravel pits in Massachusetts, Connecticut, New Hampshire, Maine, and Vermont. We isolated and purified > 20 g of quartz from each and then extracted ¹⁰Be and ²⁶Al from 7 of these samples. We measured ¹⁰Be/⁹Be ratios at PRIME lab, Purdue University. ²⁶Al data are forthcoming. 

 

¹⁰Be concentrations (n=7) range from (0.26 to 4.2) x10⁴ atoms/g (mean = (2.4 ± 1.2) x10⁴ atoms/g [1 sd], median =  2.7x10⁴ atoms/g). The highest sample concentration (OBC-93), 4.2x10⁴ atoms/g, was sourced from a delta built into Glacial Lake Hitchcock by outwash flowing south through a north/south oriented, 9 km-long col in eastern MA. The lowest value (OBC-91, 0.26x10⁴  atoms/g) was a gravel pit sample from Martha’s Vineyard. The 5 other samples had concentrations of 1.9x10⁴ (southeastern ME; OBC-116), 2.0x10⁴ (southern VT; OBC-90), 2.7x10⁴ (western CT; OBC-97), 2.8x10⁴ (Cape Cod MA; OBC-100), and 2.9x10⁴ atoms/g ¹⁰Be (western ME; OBC-110).

On average, ¹⁰Be concentrations measured in New England glacial sediment ((2.4 ± 1.2)x10⁴ atoms/g; n=7) are 20% higher but statistically similar to those measured in deglacial sediments ((2.0 ± 1.4)x10⁴ atoms/g; n=10) from the Labrador Quebec Ice Dome, 1000 km north in eastern Canada, implying similar interglacial exposure and glacial erosion histories for the eastern LIS.

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

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