Ontario is home to a weird gravity anomaly where things weigh less - blogTO

Theory Briefing

• The Hudson Bay area has a measurable gravity anomaly where objects weigh slightly less than they should anywhere else in Canada.
• One theory traces the anomaly to the last Ice Age, when massive glaciers depressed the Earth's crust and it hasn't fully rebounded yet.
• A second theory points to slow churning movements deep in Earth's mantle pulling mass away from the surface beneath the region.
• The two explanations aren't mutually exclusive — some researchers think both forces are acting together to reduce gravity there.