The last remnant of the Laurentide Ice Sheet
Contrary to popular belief, the Laurentide Ice Sheet did not completely disappear during the last deglaciation - it exists today as the ~6 mm sea-level-equivalent Barnes Ice Cap (BIC) located on the central Baffin Island plateau, Arctic Canada. Beneath its Holocene-age ice rests ice from the last glacial period which in turn overlays ice with 18O values similar to Holocene interglacial values. The presence of at least three generations of ice highlights BIC’s unique position as a natural end point of a full deglacial sequence and, conversely, a primary inception point for subsequent continental-scale glaciation. How long until BIC completely disappears? When did the Laurentide Ice Sheet become BIC during the Holocene? Was BIC ever smaller than today in the Holocene and, if so, when and why did it start to re-grow? How often during the Pleistocene did the Laurentide Ice Sheet achieve dimensions similar to today? Here, I will present a suite of in situ cosmogenic nuclide and traditional radiocarbon measurements from samples collected during a twice-delayed 2022 field campaign to BIC that tackles all these questions.
