Geology
The Bay is near the center of a major gravity anomaly which has been mapped in some detail by the GRACE satellites. Current theory suggests that about two-thirds of this effect is due to downwards mantle convection under the Bay area, while one-third is due to post-glacial rebound since the Laurentide ice sheet melted. Lands to the west of the Bay are rising as much as 17 millimetres (0.67 in) per year.
Some geologists disagree about what created the semicircular feature, known as the Nastapoka Arc, of the bay. The overwhelming consensus is that it is an arcuate boundary of tectonic origin between the Belcher Fold Belt and undeformed basement of the Superior Craton created during the Trans-Hudson orogen. Although a few geologists have argued that it is possibly related to a Precambrian extraterrestrial impact and have compared it to Mare Crisium on the Moon, no credible evidence for such an impact crater has been found by regional magnetic, Bouguer gravity, and geologic studies.
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