Abstract

Swath sonar bathymetry reveals sinuous furrows, <100 to >400 m wide, kilometers long, and <1 m to >4 m deep inscribed in semilithified clays on the southern Hudson apron. We interpret these as keel marks created by floating icebergs detached from the retreating Laurentide ice sheet since ca. 25 ka. Keel-mark orientations suggest two phases of iceberg rafting. These phases could correlate with Heinrich meltwater events H2 and H1 ca. 25 and 17 ka, bracketing the late Wisconsinan glacial maximum ca. 22 ka. During Holocene transgression, some keel marks were reworked and reformed into oblique ridges where older, sandier sediments crop out at the seafloor. Relict glacial features on the New Jersey outer shelf provide a tie between the timing of Laurentide glacial retreat and the evolution of shallow stratigraphy on this mid-latitude shelf during the last global sea-level cycle (ca. 120 ka to present).

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