We like to think of gravity being constant. No matter where we are on the earth, we weigh the same. Except that’s not actually true. As it turns out, Gravity is not uniform. It varies geographically.
The Bouguer (pronounced boo-gay) gravity anomaly is named after French scientist Pierre Bouguer (1698-1758), a prodigy who succeeded his father as professor of hydrography at the tender age of 16. Among his many discoveries was the fact that small regional variations in the earth’s gravity field could be related to the varying density of subterraneous rocks in the subsurface.
In addition to gravitational variations caused by subsurface rocks, there are also gravitational changes that are caused by what latitude you’re on, the rotation of the earth, what altitude you’re on, and even that tidal pull of the sun and moon.
If you want to look at the gravitational measurements of your area, visit the International Gravimetric Bureau. You can look up anomalies near you and visit the specific region that has gravitational anomalies and experience it yourself.
Quirks and Curiosities 