(May 11) - A mysterious dip in gravity over Canada has been a weighty topic for some scientists. Now satellite data reveal a thick ice sheet that once cloaked the region partially resolves this so-called gravitational anomaly.

Scientists have known that the Hudson Bay region features lower gravity than surrounding areas. While two theories have emerged to explain the strange phenomenon, conclusive evidence has been elusive. One theory involved a change in the area's overlying glacial weight as the Laurentide Ice Sheet melted.

The new results, reported in the May 11 issue of the journal Science, provide a crude map of the ice sheet's structure as it was during the most recent ice age. Turns out, the now-melted ice left behind an imprint from which the Earth is still rebounding, and that imprint contributes to the weird gravity.