The East Coast shoreline as it appeared 3 million years ago. The shoreline has been adjusted 82 feet (25 meters) relative to today.
A prehistoric shoreline runs along the eastern edge of North America; scientists have pointed to it as evidence that much of Antarctica melted 3 million years ago. But new research suggests this shoreline is actually about 30 feet (10 meters) lower than previously thought, meaning less ice melted than suspected.
The shoreline, which should be flat, also swoops up and down the East Coast like a set of wave crests, reflecting tugging and pushing by Earth's mantle, the layer of viscous rock leisurely oozing underneath the crust, according to the study, published today (May 16) in the journal Science Express.
The finding shows that scientists have to be careful when looking at Earth for evidence of past sea level changes from the planet's cycles of glacial advance and retreat.
For the rest of the story: http://www.livescience.com/32060-mantle-flow-changes-topography.html