The Strange Reason You'll Always Weigh Less in Canada Than Anywhere Else

"Canadians like to point out all the things they have that America doesn’t: Mounties, the metric system, universal health care. But you might not know that there’s one thing they’re a little short on north of the border: gravity. That’s right: Canada actually has less gravity than it’s supposed to. The reasons for the shortage have puzzled scientists for decades.

Gravity isn’t uniform all over the Earth’s surface. It’s a result of mass, which means the varying density of the Earth at different locations can affect how much you weigh there. Canadians aren’t all free-floating like Sandra Bullock, but the effect is definitely measurable. In the Hudson Bay region, the average resident weighs about a tenth of an ounce less than they would weigh elsewhere. (And much less than they’d weigh if they moved south, where there are more Tim Hortons. But that’s a different story.)

Satellite data collected by GRACE—the Gravity Recovery and Climate Experiment—has recently solved this mystery. During the last ice age, Canada was covered by a vast glacier called the Laurentide Ice Sheet. This sheet was two miles thick over northern Quebec and stretched as far south as modern-day New York and Chicago.

Ice is heavy, so five million square miles of it pushed down on the rock underneath, squishing it like a Nerf ball. When the ice began to melt, about 21,000 years ago, the Earth began to spring back, but, like a Nerf ball, it takes a while. To this day, the Earth in the Hudson Bay region is still deformed, with lots of rock-mass having been pushed outward by all the ice. Less mass means less gravity.........

http://www.cntraveler.com/daily-traveler/2014/04/the-laurentide-ice-sheet-maphead?mbid=nl_daily_traveler&sp_rid=NDY0MjI1MzI0NTAS1&sp_mid=6379234