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

Glaciers and ice sheets shaped the landscape of the Northeast. Ice continues to shape the landscape of alpine and polar regions. We welcome submissions on glaciers &  ice sheets of any size, shape, age, and location.

Monday, 23 March 2026
1:30 PM - 5:30 PM
CCC, Ballroom C

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

Paper number: 35-3
Program: Technical Sessions
Time: 1:30 PM – 1:30 PM

Authors

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

doi: 10.1130/abs/2026NE-411320

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