The study shows that the gravity anomaly over Hudson Bay is linked to incomplete post-glacial rebound, but also suggests that dynamic topography from mantle convection could explain it. By analyzing the global gravity field, the researchers found that the Hudson Bay gravity low is unique, with high amplitude in the spectral band where the Laurentide ice load's effect is strongest and where viscous relaxation times are longest. They estimate that about half of the gravity anomaly is due to incomplete post-glacial rebound and developed a mantle viscosity model that explains both the gravity signature and uplift rates in the central Laurentide and Fennoscandian regions. This model has a viscosity jump at 670 km depth, similar to dynamic models of geoid highs over subducted slabs, but lacks a low-viscosity asthenosphere, consistent with a higher viscosity in the upper mantle beneath shields than in oceanic regions. The study also notes that delayed rebound is not the dominant process generating variations in the global gravity field.The study shows that the gravity anomaly over Hudson Bay is linked to incomplete post-glacial rebound, but also suggests that dynamic topography from mantle convection could explain it. By analyzing the global gravity field, the researchers found that the Hudson Bay gravity low is unique, with high amplitude in the spectral band where the Laurentide ice load's effect is strongest and where viscous relaxation times are longest. They estimate that about half of the gravity anomaly is due to incomplete post-glacial rebound and developed a mantle viscosity model that explains both the gravity signature and uplift rates in the central Laurentide and Fennoscandian regions. This model has a viscosity jump at 670 km depth, similar to dynamic models of geoid highs over subducted slabs, but lacks a low-viscosity asthenosphere, consistent with a higher viscosity in the upper mantle beneath shields than in oceanic regions. The study also notes that delayed rebound is not the dominant process generating variations in the global gravity field.